Shrinking The Cat Pa

Overview

In this timely and controversial work, Sue Hubbell contends that the concept of genetic engineering is anything but new, for humans have been tinkering with genetics for centuries. Focusing on four specific examples?corn, silkworms, domestic cats, and apples?she traces the histories of species that have been fundamentally altered over the centuries by the whims and needs of people.

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Overview

In this timely and controversial work, Sue Hubbell contends that the concept of genetic engineering is anything but new, for humans have been tinkering with genetics for centuries. Focusing on four specific examples—corn, silkworms, domestic cats, and apples—she traces the histories of species that have been fundamentally altered over the centuries by the whims and needs of people.

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Editorial Reviews

From The Critics
A few years ago, when Monsanto created a strain of genetically modified corn that was resistant to caterpillars, the media suggested that scientists were inventing "frankenfoods" and playing God in their laboratories. Hubbell points out that humans have always tinkered with the world to make it better suit our needs and tastes, including changing the basic genetic programming of other species. The author tells the story of a few plants and animals (including the cat) that wouldn't exist but for genetic modification and selective breeding. With verve and wit, Hubbell reveals just how deeply the natural order is entangled with human hopes and ambitions, and her book provides a context for the current debate over the proper limits of genetic research. Fascinating and delightful, this is natural-history writing at its finest.
—Eric Wargo

Publishers Weekly
In this fresh and personalized take on genetics, Hubbell (Waiting for Aphrodite, etc.) argues that "we have been `genetic engineers' in the past, and we will continue to do so in the future." There is currently a spate of books weighing in on both sides of the controversial genetic engineering debate, and this one stands out for its memoir feel as well as its straightforward thesis, which aims to put the debate firmly in the context of past genetic tinkerings. Hubbell shows how farmers 7,500 years ago engineered what came to be known as corn from a botanical anomaly of a kind of "naturally occurring" grass (though when finished with this book, readers may find themselves second-guessing what constitutes "natural"). The result was a dependable and essential man-made foodstuff, which, because of its genetic enhancement, cannot reproduce itself each planting season today without human help. A similar case of mutual dependence resulting from our ancestors' genetic tinkering, Hubbell shows, is the silkworm, a species "minted by human ingenuity" to spin its costly trade commodity, but at the expense of its protective coloring and ability to fly. Today, the silkworm depends on its human keepers for its food and shelter, as does Hubbell's next case study, the house cat. Like the silkworm, the modern-day cat lost its edge in the wild through domestication, in the cat's case through diminished size, sight and reflex ability. Finally, Hubbell shows how apple growing in America was perhaps "the greatest genetic experiment ever performed by human beings," yielding as many as 7,000 genetic varieties by the 1800s, a number that has since been narrowed by market demand to about a dozen. Throughout,Hubbell delves into the history behind her case studies, interspersing her narrative with her accounts of living in Washington and Maine. (Oct. 15) Copyright 2001 Cahners Business Information.
Library Journal
Amid the heated public debate and misinformation about the genetic engineering of plants and animals emerges this fact-filled history of how genetic engineering began, how it has been used, and how humankind has benefited from a combination of natural selection and scientific manipulation of genes. Hubbell (Waiting for Aphrodite) shows that genetic engineering has always been with us, illustrating by way of silkworm breeding from its origins in China to the New World, where it spawned an industry that depends on genetics to thrive; the domestication of corn from its wild state to the product we eat today; how we turned wildcats into house cats by selective breeding that changed size, color, and demeanor; and breeding apples to improve taste, quality, and size. Hubbell describes the achievements and the mistakes of these endeavors in plain English, with no confusing scientific terminology to bore or distract readers. A humane perspective on the impact of genetic engineering in our lives; highly recommended for popular science collections. [Previewed in Prepub Alert, LJ 6/15/01.] Irwin Weintraub, Brooklyn Coll. Lib., NY Copyright 2001 Cahners Business Information.
Kirkus Reviews
A corrective to Frankenfood alarmists: Genetic engineering of plants and animals has been going on for millennia, thanks to humankind's tinkering. Indeed, a better descriptor for our species, naturalist Hubbell (Waiting for Aphrodite, 2000, etc.) argues, would be Homo mutans-man the changer-because wherever people have settled, they have altered the natural world by selective breeding, as with the creation of corn from a grass native to the New World tropics. A bisexual transformation 7,500 years ago evidently resulted in plants that hoarded female energy in the form of primitive kernels rather than typical grass seed. Indian farmers' selective cultivation of these kernels led to the creation of a new species, the sturdy stalks and ears we know today, now completely dependent on human intervention for its propagation. Hubbell's focal examples include the cultivation of the silkworm, the domestication of the cat, and the development of the commercial apple industry. The production of silk in China is probably the result of crossbreeding several species of moths, followed by selective inbreeding and mutant selection to generate a new species that can spin a cocoon consisting of one long continuous silk filament-though it is now too heavy to fly. The domestication of the cat by the middle of the second millennium b.c. is indeed a case of selecting-for size, color, and disposition-from the larger, well-camouflaged, super-wary African wildcat. Unlike other experiments in human tinkering, however, the cat has maintained some independence, in effect domesticating us. Hubble's concluding story of apples is one of extraordinary genetic complexity in which cultivators early on learned that ifyou wanted to produce a favored variety you had better do it by grafting. Though she worries about limits-too many people making too many changes affecting too many fellow creatures-Hubbell offers hope that an appreciation of past human tinkering, along with an understanding of just how close all life is genetically, will yield an ecological intelligence, and not an impotent fear and trembling before today's biotechnology. Author tour
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Product Details

  • ISBN-13: 9780618257485
  • Publisher: Houghton Mifflin Harcourt
  • Publication date: 12/12/2002
  • Edition description: Reprint
  • Pages: 192
  • Product dimensions: 5.00 (w) x 8.00 (h) x 0.44 (d)

Meet the Author

Sue Hubbell is the author of, among other works, A Country Year and A Book of Bees, which was selected as a New York Times Notable Book. She lives in Maine and Washington, D.C.

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Read an Excerpt

Preface

Genetics. A branch of biology that deals with the heredity and
variation of organisms and with the mechanisms by which these are
effected.

Engineering. The science by which the properties of matter . . . in
nature are made useful to man . . .
-- Webster's Third New International Dictionary

I'd not intended to write another book for publication after I
finished my last one, Waiting for Aphrodite. That book had seemed
final to me, and I wanted to devote myself to other things -- working
in my woodlot, for instance, or building stone walkways around the
house.

But as I worked, thinning out trees here and there,
encouraging those I liked, cutting down those I didn't, hauling rock
from this place to that, I reflected on my proclivity for rearranging
bits of the world, an activity so characteristic of the human animal.
It is a subject I've written about in the past but clearly have not
exhausted.
About that time, stories concerning genetically modified
organisms began to appear in newspapers everywhere. I read them with
interest, not only because they were good examples of our human
penchant for fiddling with materials that are to hand but because all
parties to the furor that erupted seemed to be talking past one
another.
The public, which had forgotten whatever high school biology
it had learned, was saying that something new, terrifying, and
possibly devious had been kept from it, something having to do with
the sanctity of species. The scientists, whose work was built on a
body of genetics research stretching back a hundred years, appeared
startled to find that the term "species" was understood by the public
in such a fixed way. Biologists, for whom "species" had become simply
a useful word, were used to reassigning plants and animals to
different species. They knew that the genetic similarities among
species were far more important than their differences. They saw the
uniformities of biological processes as transcending the separateness
of individuals. Biologists had their own questions about genetic
engineering, questions that weren't making it into the popular media,
but they understood that manipulating a gene or even putting a gene
from one kind of life into another wasn't such a stretch. They had
been saying such things for some time, but in words so obscure and
papers so technical that no one outside their particular fields had
heard them.
The corporations that were exploiting genetic research, had
begun profiting from it, and had every expectation of profiting even
more were alarmed by all the attention and turned, as structured
organizations always do, to spin control, which fooled no one and
made the public doubly suspicious.
I knew, perhaps, a little more than the general public did
about genetic engineering, but certainly not as much as the
scientists. I knew, for instance, that we had been fiddling with the
genetic identities of domesticated plants and animals ever since we
had become human. I knew that in the process of that fiddling --
engineering by another name -- we had actually created brand-new
kinds of life, species, if you will, based on but different from the
wild forms that had furnished the raw material -- wheat and corn, for
instance, to name but two. And I knew that to a greater or lesser
degree those new species needed us in order to thrive. The enormous
sums of money being invested in research relating to modern genetic
engineering by agribusiness and pharmaceutical corporations, sums
they believed would be repaid many times, seemed like a new element
in the story. But in truth, merchants and traders from ancient times
onward had been in the business of bringing more desirable, and hence
more profitable, goods from there to here: amphoras of better olive
oil brought higher prices in places where lesser olives grew. Sheep
with denser woolly coats could be sold to advantage far from their
birthplace.
But I had a lot of questions. How had merchants spread the
new plants and animals from one end of the earth to the other? What
was the effect of transplantation on the plants and animals? Could
those species whose unique genetic makeup was the result of our
handiwork live without us? How did all those genetically modified
organisms affect human history? Until recently, the genetic changes
that created new species had been brought about through breeding,
through the isolation and encouragement of genetically interesting
recessive genes and mutant plants and animals, and through the
artificial creation of mutations themselves. From the standpoint of
natural selection, artificial selection speeded up the process of
evolutionary change. Still, species change had been slow compared to
what researchers today can do, with our knowledge of genetic
processes and the tools we have to manipulate those processes
directly. Does the modification of species in the past have anything
instructive to tell us about the moral and ethical questions
concerning modern genetic engineering?
Those questions interested me, so for a time I put off work
in my woodlot and let the rocks lie. To answer my questions, I chose
a few animals and plants whose genetic identities we have tinkered
with to varying degrees and that are more or less dependent upon
humans. In the course of examining our shared histories, I discovered
that our experiments in manipulating species have had unintended
consequences. I've answered my original questions to some degree, but
I've found a lot of new ones. These relate to an enormous problem
confronting humankind today. For the purposes of this book I will
call it the problem of limits: How do we limit the effects of six
billion of our kind on the rest of the world and avoid making
alterations that harm other kinds of life and change the world so
drastically that we can no longer live in it ourselves?
I am encouraged and hopeful about this large, general, and
occasionally boisterous public debate over genetic engineering. I
believe it is long overdue, and I also believe that it will become,
in time, a way to and a part of the solution of the problem of limits.


Chapter One

"I make thee maister," seid Robyn Hode.
"Nay . . . let me be a felow," seid Litull John.
-- Robyn Hode and Monk, 1450

We, the namers, call our species Homo sapiens, the sapient,
intelligent, wise sort of human. It is the name by which we
distinguish ourselves from all other kinds of life, including those
other species of the genus Homo: H. erectus, those who stood up, H.
habilis, those who made stuff. They, along with the
australopithecines, Cro-Magnons, and other relatives of our fine
selves, managed to get themselves extinguished somewhere along the
line, but we thrived and continue to do so. How wise.
Tens of thousands of years of natural selection acted upon
our ancestors to produce our species of humankind with our
complicated, much-folded brains and clever fingers, attributes that
have allowed us to spread all across the planet and even a little
beyond it. In biological terms, we have a very big ecological niche.
We've all seen those lists that appear in the newspapers now
and again ranking animals by intelligence, giving the pig a higher
grade than the horse, and the pigeon higher than either. On those
lists, of course, we always come out best of all, outranking even the
animals we regard as suspiciously bright, such as dolphins or apes.
We win because we make the rules: we define intelligence as our kind
of knowingness and dismiss any other animal knowingness as
mechanical, instinctual, "hard-wired." That is the sort of verbal
sleight of hand I would have been graded down for in high school
debating competitions because it is an error of circularity. We
define intelligence by holding up other animal minds to ours and to
our way of understanding, then dismiss their ways by giving them a
lesser name.
Considering all the world's other intellectual follies, the
pop biology represented by these lists hardly deserves to be fussed
about. Nevertheless, it is heartening to note that there have always
been dissenters from the conceited notion that we are the wisest
animals on the planet.
Margaret Cavendish, a seventeenth-century Englishwoman, a
bluestocking condemned by Samuel Pepys as "ridiculous" and praised by
Charles Lamb as "princely," wrote:
For what man knows whether fish do not know more of the nature of
water, and ebbing and flowing and the saltiness of the sea? Or
whether birds do not know more of the nature and degrees of air, or
the cause of tempests? Or whether worms do not know more of the
nature of earth and how plants are produced? Or bees of the several
sorts of juices of flower than man? . . . Man may have one way of
knowledge . . . and other creatures another way, and yet other
creatures' manner of way may be as intelligible and instructive to
each other as Man's.
As a human, I've never been flattered by my own exaltation in
those intelligence-ratings lists, for I've spent my life with other
animals and have come to know that they have considerable
capabilities that I lack. I don't expect them to take human IQ tests,
because they don't live human lives. They live dog, cat, honeybee,
monkey, lion, cricket, salmon, squirrel, pigeon lives, and I'd fail
their IQ tests as readily as they would fail mine. For instance, I'm
no good at bones.
Some years ago I shared my life with a dog named Tazzie the
Good, a Belgian shepherd-black lab cross. Tazzie had all the
genetically determined traits that dog breeders had drawn out over
generations of inbreeding her ancestors, along with some hybridism
that juggled those traits a little. More thoughtful than the average
lab and a lot mellower than the average shepherd, she was obedient
and devotedly loyal to me, wanting only to learn what I wanted from
her and then joyfully doing it. She accepted other humans with grace
and dignity. She was the definition of Good Dog. She had massive jaws
that could have killed smaller creatures easily, but she used them
gently because I required it. When Black Edith Kitty was a mere
kitten, he would tease Tazzie into playing with him. (Like the boy in
the Johnny Cash song, Black Edith has a girl's name.) Tazzie would
hold him between her paws as though the cat were a living bone and
delicately gnaw on him. When Black Edith had had enough of this
slobbery sport, he would use his claws to rake Tazzie across her soft
black nose, and she would let him go.
Even compared to other dogs I have known over the years,
Tazzie had extremely high bone intelligence. My husband and I have a
house in a tidy neighborhood in Washington, D.C. No one there is a
trashy sort of person who would strew garbage about or leave it in an
uncovered bin. Yet when we took her on evening walks around the
block, Tazzie would always find a bone. Not one night, not
occasionally, but every night. If I'd been sent out on a treasure
hunt and told that my mission was to find, in the dark, a bone in a
one-block circuit of that neighborhood, I'd have failed -- not just
once but night after night.
Tazzie was bright about bones. I am not. Tazzie was sapient
in a dog's world, many aspects of which are not mine. Her world and
mine overlapped at certain points -- we were companions -- but our
skills, our intelligences, were for our own ways of life, not each
other's. And those ways of life were determined by different
biologies, different configurations of our DNA.
Knowingness -- call it intelligence, call it instinct, call
it whatever you will -- is always knowingness for some purpose. It is
not an abstraction, not some objective gold standard. I'd never have
expected Tazzie to discuss the finer points of the role of NATO in
the post-Cold War world, and she accepted that I was stupid about
bones, although she never quite gave up trying to interest me in the
stone game. That was a game she had invented as a puppy, when we
lived beside a river in the Missouri Ozarks. She would select a stone
and drop it in my lap to throw for her. I'd toss it into the river,
and she would leap through the air following the stone's trajectory
and watch it splash and disappear. She had no interest in retrieving
it. She was not that kind of a dog. Instead she'd bring a new stone
to me and whine enticingly, urging me to throw it. As she aged and
grew stiffer, she had as much fun simply sitting beside me and
watching me throw stones. Her eyes would follow the stone's arc and
its splash, and then she would whine and beg me to throw another. I
always got bored with the stone game before she did, but now that she
is gone I wish I'd spent more time chunking stones into the water for
her and less time talking about NATO at Washington dinner parties.
Some time has passed since Tazzie died in the fullness of
age, but I still miss her. She was my shadow. I can still feel her
chin on my knee when I am driving the car, her quiet paw on my foot
as I sit writing. She was a very present animal.
All the years I've spent hanging out with other animals and
the zoologists who study them have led me to think that it is
arrogant and even silly of us to name ourselves for our intelligence.
But we have another preeminent trait, one that we are good at beyond
all other animals, and that is our ability to modify the world to
make it nice for ourselves. A more accurate name for us might be Homo
mutans, the human who changes things. We do not accept what we find.
We use that brain and those fingers, with the extensions we've made
for them, to alter, build, excavate, extend, recombine, fuss, and
fiddle to make the world comfortable and more interesting to us.
Other animals modify their particular worlds, of course, to
the extent that they are able. Honeybees harvest plant sap and
process it into a glue to chink their hives against winter drafts.
Bowerbirds gather up fresh flowers to display in the competition for
mates. Caddis fly larvae make protective shelters out of grains of
sand. Last winter a mouse stole all the little wooden vegetables from
a dollhouse I have for grandchildren. I do not understand the mouse's
purpose: when I pulled open one of my desk drawers I found within it
a mouse nest made of pulled chair stuffing surrounded by the tiny
wooden carrots, cabbages, and rutabagas. Both chimpanzees and certain
insect-eating finches use twigs to stir up ants and other bugs from
their nests so that they are easier to catch and eat. I remember a
bold tufted titmouse who made life uncomfortable for a friend of mine
by making unrelenting, swooping passes over his curly head of hair
and then, with great daring, pulling out several hairs. We watched as
it skillfully wove them into a nest.
Tinkering with existing circumstances and materials is
characteristic of life in all its forms, but we humans have better
biological equipment for this purpose. And as a result we are more
thoroughgoing. We are the fiddlingest animal the world has ever seen.
Now that we are six billion in number and have more powerful
tools than ever to modify the planet, we are starting to wonder
whether we are fiddling so much that we and other kinds of life may
not be able to continue living on it. We are finally beginning to ask
where all this fiddling is taking us. Impatient environmentalists
sometimes get discouraged and think we aren't getting anywhere, but
we've only recently become aware of the problem and have just
commenced asking questions. It is only about one hundred years since
we filled up the habitable earth and far fewer since we realized that
there are too many of us and only just now that we are attending to
the fact that we do not have an entirely happy effect on other kinds
of life.
We will have to ask a lot of questions before we can figure
out how to frame those that might help us solve the problems we have
caused. And we are just beginning to pose the necessary questions
about limits: limits to our own numbers, limits to the extension of
human life into prolonged senescence, limits to our consumption and
exploitation. These are ferociously difficult questions because our
biological design is to increase willy-nilly and to grab whatever is
available (as it is for any species). But we are developing a modicum
of self-awareness and a struggling, if not always successful,
objectivity, and that makes me optimistic about our kind. It may be
that none of us alive today will be around long enough to see
solutions to the problems of limits, but I think our descendants will
find them. And when they do, we will deserve to be called sapiens.
One of the questions we've asked as we began to consider our
impact on the world runs something like this: Weren't there --
somewhere, sometime -- pure and unspoiled people who made better
arrangements with the world than we have? Aren't today's "primitive"
people rather like that? The answer to both questions is, probably
not. As Jared Diamond, the physiologist who has studied and thought
about people in out-of-the-way places, often points out, people
everywhere are as exploitative of the resources they find as their
technology and numbers permit. It is easy to believe that those who
are fewer in number somehow have better intentions toward the planet
than we.
That river where I used to chuck stones for Tazzie is named
the Jack's Fork. Part of the first National Scenic Riverway
designated by the U.S. Park Service, it runs through rugged land in
the Ozarks of southern Missouri. While I lived there I came to know a
federal archaeologist who had excavated along its banks and had found
that a long time ago -- I no longer remember the dates -- there had
been densely populated Indian villages along the river. The Indians
had cleared the land and farmed the thin soil. Farming in the Ozarks
is a heartbreaking business, as the white settlers were to discover.
The land is too steep and the soil too thin and poor for good crops.
The archaeologist had found artifacts -- pots, bowls, baskets, and
arrow points -- in the remains of the Indian houses. The oldest
artifacts were made with expertness and grace, but the most recent
ones lacked both qualities. He had arranged a collection of arrow
points by date of making, and they became cruder and cruder over
time; the baskets and pots also became increasingly rougher and
coarser, as if they had been made by a people who had grown sad and
ineffectual. There were signs that in the end the people had left
quickly. The archaeologist suspected that disease of some kind had
swept through the towns (as evidence suggests happened elsewhere in
North America) and that those left were too few or too weak to defend
themselves.
Dust and dead leaves would have blown through the empty
villages (some of which had been burned). Gradually over the years,
their garbage dumps and home debris, their tools and pots, were
covered and buried under accumulating soil. Weeds crept into the
fields where they had grown corn, a crop Europeans had yet to learn
of. Low bushes, then trees followed. The Jack's Fork, no longer silty
from farmland runoff, ran clear. Slowly the Ozarks took on the
character it had when Americans of European descent found it in the
1800s, a wild place full of big pine, oak, walnut, cedar, and hickory
trees, clear streams, and wild animals. There were no signs left to
tell that it had once been home to many people who had used
everything they found there.
The story was repeated in many parts of the Americas. Peoples
from the Mayans, with their high culture, to the Mound Builders
increased in numbers, altering and using whatever they could, until
life became precarious for one reason or another and their ways
failed them. Their descendants, few in number, lived on in poorer
circumstances.

The Indians whom the Europeans first met when they came to North
America, even if they were descendants of people who had known
greater amenities, had more skill at living from the land than the
Europeans, who were mainly city folk with no knowledge of fishing,
hunting, or farming. The native plants -- wild berries, nuts,
pawpaws, and the like -- were not enough to sustain them, and they
did not even recognize some of what was available as food. Lobsters,
for instance, they regarded as offal. In 1622 William Bradford, one
of the early Pilgrim dissidents who had come to these shores on the
Mayflower, wrote a letter describing the settlers' privations, using
as an example their humiliation and sadness when, on the occasion of
receiving visitors, "the sole dish they could present their friends
with was lobster."
Some settlers starved, but some took lessons from the
Indians, who were farming several staples -- sweet potatoes, squash,
and corn -- unknown to the Europeans. They quickly learned how to
grow them. None of these crops was native to North America; they had
all come from the New World tropics and had been cultivated and
improved over the centuries. Of the three, corn would become the most
important foodstuff that the New World gave to the Old.
Corn, like squash and sweet potatoes, was the result of the
sort of fiddling with materials at hand that has taken place all over
the world and is now called agriculture: the human creation of new
botanical species whose genetic structures are distinct from those of
their wild ancestors.
Corn is basically a grass, a member of a large family of
plants that includes not only the green kind growing as lawns but
also bamboo, rice, and sugar cane. Corn betrays its origins as a
neotropical grass by a peculiarity of leaf anatomy -- the clustering
of photosynthetic cells, the engines that turn sunlight into plant
energy -- around the leaf's midrib. This configuration is typical of
plants growing in hot, dry places. In temperate-zone plants, by
contrast, the photosynthetic cells are ranged around the leaf veins,
where they can respire in cooler temperatures.
The earliest farmers selected certain plants, some of which
were mutants, that produced unusually good things to eat and saved
their seeds to plant again. They planted the selected seeds, cosseted
the plants that grew from them, and repeated the process again and
again until they had created crops that were dependable and
productive. Those traits are genetically determined, and thus those
early farmers were rearranging genes, even though they did not know
what genes were.
The ancestor of corn is lost in some pre-Incan, pre-Mayan,
pre-Aztec past, but a respectable hypothesis that accounts for many
aspects of the corn plant has been put forward by Hugh H. Iltis, a
botanist at the University of Wisconsin, who has spent much of his
research life thinking about the history of corn. He conjectures that
corn originated 7,500 years ago in Central America as a botanical
anomaly when an existing grass (probably quite like corn's nearest
modern relative, called teosinte) had its male parts hijacked by its
female parts. As a result, the plant produced very large seeds
growing against a protective sheath (which would in time become a
husk). They looked more like tiny kernels of corn than like ordinary
grass seeds. Such a transformation may sound bizarre, and it is
uncommon, but it is an expression of relic bisexuality that sometimes
does take place in plants during periods of stress -- during an
unusually wet rainy season, for instance. And that sort of stress is
just what may have started corn on its way, according to Iltis. He
adds that in the wild, when the weather pattern returns to normal,
this relic bisexuality would disappear.
Strictly speaking, these proto-corn plants were, as Iltis
phrases it, a genetic "catastrophe," hoarders of female energy in the
form of seed. But Indian farmers kept the seeds and planted them in
rows, which were more convenient to tend and weed than scattered
plants. They must have continued to select and plant seeds from
plants that grew straighter and sprawled less than the original
grasslike forms, because the plants genetically inclined to slim
tallness were easier to farm. In the course of time this wonderful
new crop plant was carried northward. The earliest archaeological
evidence of corn in North America is about two or three thousand
years old. Tiny kernels of popcorn were found in a cave in New Mexico
along with tools and other signs that a family had lived there. The
kernels, the discoverers found, could still be popped.
Those innovative early farmers would have been quickly
encouraged in their agricultural efforts because the food value of
corn rapidly improves with selective planting, as was demonstrated in
an experiment conducted at the University of Illinois. The
agronomists selected and planted corn seeds that were slightly higher
in oil content -- a genetically determined trait -- than the rest of
the seeds. They repeated the process after each harvest, always
saving the seed with the highest oil content for replanting. When
they graphed the results, they found a steady upward curve that
showed no sign of leveling off when they brought the experiment to a
close after fifty generations.
Even though those early farmers couldn't reach into the grass-
becoming-a-corn-plant and fiddle with its genes as we can today, they
could see and taste the expression of its genes. Biologists call the
visible package of expressed genes the phenotype. When you look at me
or I look at you, we see a phenotype. The stalk of corn, with its
coarse, bladelike leaves, its silk, its corn kernels neatly and
greenly wrapped, is the phenotype of its expressed genes. Not all of
its genes are expressed, nor are all of yours or mine. All of us --
humans, Tazzie the Good Dog, a corn plant -- carry a unique genetic
profile in our cells. That profile includes both expressed genes and
ones that are not expressed: genes that are nonfunctional (as far as
we can tell) and those that are recessive and thus masked by the
dominant form of the same gene. All of those genes -- unfunctional,
expressed, and unexpressed, dominant and recessive -- make up an
individual's genotype. Genotype. Phenotype. It oversimplifies, but it
helps to think of a package delivered by the UPS man. The package is
the phenotype. You can tell something about what is inside by the
size of the box, its weight, and the way it does or does not rattle.
But you can't tell exactly what is inside until you open it. The
contents are the genotype.
The individual genes for any plant or animal can take
different alternative forms, which are called alleles. In sexual
pairing, genetic material from both parents is shared to make up a
new individual. In humans, for instance, brown eye color is
controlled by a dominant allele and blue eye color by a recessive
one. Two brown-eyed parents may each carry a blue eye-color allele,
and if, in the genetic sorting that takes place in mating, their baby
receives both blue-eyed alleles, she will have blue eyes. Their baby
has a phenotype all her own.
It was only about one hundred and fifty years ago that the
Austrian cleric Gregor Mendel began to elucidate this process, and it
is startling to realize that the word "gene," so much a part of
contemporary vocabulary, was coined in its modern sense only in 1909
(by Wilhelm Johannsen, a Danish agronomist).
Inheritance, and hence genetics, can be complicated for a
number of biological reasons, and when Mendel began his work on what
he called "factors of inheritance," he had the bad luck to choose as
his first experimental model an animal that featured some of those
complications: the honeybee. His experiments ended with confusing
results, but fortunately he was a persistent man. Drawing on his
interest in plant hybridizing, Mendel chose peas as his next
experimental model. And peas, although Mendel could not have known it
beforehand, are, fortunately, simpler genetically. With his pea
experiments he demonstrated the emergence of recessive
characteristics. Peas with red flowers and long stems carry dominant
alleles of certain genes, and when they are crossed with white-
flowered, short-stemmed peas, which have recessive alleles of the
same genes, the first generation of plants all has red flowers and
long stems. But when that first generation is intermated, the white
flowers and short stems reappear in the next generation. And, what is
more, they reappear in a tidy, predictable ratio. (Some suspect that
his results were a little too good, that he fudged a little.) Later
Mendel tried to test his conclusions on other plants and, once again,
was left with more questions than answers and grew discouraged.
A basic understanding of how recessive traits are expressed,
along with a new understanding of some aspects of inheritance that
bewildered Mendel, has become the stock in trade of horticulturists,
animal breeders, and agronomists.
In the wild, natural selection nudges and prunes the
genotypes of plants and animals toward toughness, vigor, and
successful reproduction and in that process maintains within the
population a characteristic ratio of allelic frequency. But when
artificial selection takes over, the story changes. One of the tricks
that breeders of plants and animals had learned long before Mendel
was that close inbreeding, although it might decrease vigor, could
bring out traits we liked. Close matings to bring out recessive
alleles and preserve mutations have created dogs with floppy ears,
cats with no hair, and pigs with extra loin-end vertebrae and hence
extra pork chops. Those attributes are ones that we fancy, even if
the wild, harsh world does not.
Wild grass, corn's ancestor, shed its seeds abundantly and
freely. Biologists think of corn as a "botanical monster," for its
seeds, wrapped in unnaturally tight husks, do not disperse and plant
themselves. And, even if a husked ear falls and is buried in the
soil, the young shoots growing from the kernels die because they are
overcrowded. But those tightly clustered kernels in their waterproof
husks are just what we want. Never mind that corn does not replant
itself. We will plant it, just as we will take care of its lack of
vigor, its vulnerability to pests and diseases. Corn is a man-made
plant, and in return for the good features we have drawn from its
genotype, we will take care of it.
If little green men were to swoop down from the sky one day
and kidnap all of humanity in their spaceships, our descendants --
brought back to the planet after five thousand years of good
behavior -- would find no corn. Corn has to have human beings if it
is to live and grow and reproduce.
After those first grateful European settlers learned how to
grow corn, it soon became a sustaining crop. They could feed it to
livestock or eat it directly. They could grind it into meal, which
could be boiled into mush or fried into journey cake. A mash prepared
from corn made an Everyman's tipple. Over the several hundred years
since we began to grow it, new varieties of corn have been developed
to suit new purposes. As anyone who drives through the Midwest in
summertime might suspect, corn is the number-one grain grown in the
United States. Just under ten billion bushels of it are grown every
year -- three times as much as its nearest rival, soybeans. Most of
this harvest isn't the sweet corn sold at Mr. and Mrs. Smith's
roadside stand. It is corn for animal feed, corn for ethanol, corn
for starch, and corn for syrups to feed the world's seemingly
insatiable taste for sweet snack foods and drinks.
That summertime driver can't help but notice how much growing
room corn takes up: the fields look endless. The United States is the
world's biggest producer of corn and devotes more acreage to it --
more than seventy-two million acres -- than any other country does.
But extensive stands of corn (or any other plant) are a wonderfully
attractive lure for pesty creatures and diseases, which sustain
themselves and multiply on its bounty.
Corn borers are corn growers' most worrisome insect, hard to
treat because they penetrate the plant and do not stay long on the
outside, where they can be conveniently sprayed to death. They are
the caterpillars of a modest-looking gray-brown moth, Ostrinia
nubilalis, and they tunnel through the cornstalks and prop roots,
even infesting the tassels of the ears. The moth came from Europe,
where it dines on other plants as well and is less of a pest, not
only because less corn is grown there but also because it has been
there for a very long time and is kept in check by a variety of
diseases and predators with which it has evolved. In North America
the caterpillars found corn much to their liking and thrived in the
absence of predators.
Over the years, agronomists have found a number of ways to
deal with corn borers. Birds will eat the moths' eggs as well as the
caterpillars, and when corn is grown in small plots with hedgerows
around them, birds can find places to nest nearby. A variety of
insecticidal sprays, including some that are illegal in the United
States today, such as DDT, were used with modest success. Some
cultural practices, such as plowing and disposing of infested stalks,
helped when farms had enough hands to do those chores. Certain
strains of corn show more resistance to borers than others, and for a
while agronomists worked at developing that resistance genetically.
They also imported, from Europe, disease organisms and predators that
attack corn borers with fair success. All of those practices are more
helpful for small stands of corn than for large ones. But small
plantings are more labor-intensive than current agribusiness profit
margins allow.
Our talent for fiddling with materials to hand -- making up
corn in the first place, concentrating it in monoculture stands, and
inadvertently bringing corn borers to it -- created a problem. Homo
mutans is good at finding a solution to a specific, limited problem
by bringing in another technological fix. Up until half a century
ago, we solved problems of this sort genetically by crossbreeding --
some of it pretty fancy, to be sure -- and by manipulating the
reproductive process to bring out the expression of genes in which we
were interested. We may have had a more sophisticated understanding
of the genetic determination of characteristics than the Indian
farmers who developed corn those thousands of years ago, but
essentially we were continuing to do what they had done: taking stock
of the phenotype.
But in the past fifty years, as the structure of DNA has been
elucidated and molecular biologists have learned what happens when
gene switches are flipped, biotechnicians have learned how to reach
inside cells and fiddle directly with those processes. The fields of
study that have grown from this new understanding are exciting and
use a lot of shiny, expensive machinery. They have drawn many of our
best young biologists, because it is easy to get funding for their
work from the agribusiness and pharmaceutical corporations that stand
to gain from their discoveries.
What we have learned to call recombinant DNA technology
(which is, essentially, reaching inside and fiddling with the genes
directly) has begun to produce profitable substances, including
hormones such as insulin for diabetics. That invention was helpful
for humans and lucrative for the corporations. The agricultural
biotech companies used the same techniques to produce bovine growth
hormone. BGH obviously provides financial benefits not only to its
manufacturers but to industrial dairies (more milk from fewer cows),
despite the physiological price paid by the particular bovines into
whom it is injected.
Biotechnology in the past several decades has been able to
slip interesting genes from one organism into the genotype of
another. In crop plants and animals, this produces changes much more
precisely, directly, and quickly than does crossbreeding. And this
form of fiddling we have learned to call transgenic engineering. A
bacterium, Agrobacterium tumefaciens (which in its original host
causes the disease crown gall), was used to shoehorn into the
genotype of tobacco plants certain genes that would provide
resistance to diseases, insects, and herbicides. That worked so
nicely that the same method has been used with other crop plants.
Biotechnicians learned to put extra growth genes into fish farmed in
captivity to make them grow faster and turn a quicker profit. They
put a moth gene into apples to produce a degree of resistance to fire
blight. Monsanto, one of the agribusiness giants, is developing a
corn plant that may produce plastics, even pharmaceuticals, courtesy
of a cluster of bacterial genes. Using a similar method, the seed
company Asgrow has developed squash seeds that are resistant to
disease. By 1999 half of the soybeans growing in U.S. fields had been
genetically rejiggered to withstand weedkillers.
Until recently, all of these developments sounded like good
news to many people, yet another happy result of sparkling new
technologies. To agronomists, developing plants with a genetic
resistance to weedkillers seemed a particularly forward-thinking
thing to do. A couple of generations ago, plowing and cultivating
kept the weeds in farmers' fields in check. But those techniques kill
earthworms, which help increase the soil's fertility. Plowing and
cultivating also make the soil fluffy and loose so that the wind can
blow it away, as it did in the Dust Bowl drought in the 1930s. In the
aftermath of that disaster, agronomists invented the way most
agriculture is practiced today, the no-till method. With the plow and
the tiller on the scrap heap, earthworms thrive, the soil stays in
place, and less labor is required to grow crops. But when soil is not
plowed and tilled, weeds proliferate, choking out crop plants. As a
result, weedkillers -- herbicides -- have replaced cultivation. But
weedkillers are not selective, and unless care is taken, they can
kill crop plants, too. The agronomists reasoned that it would be
useful to put weedkiller resistance directly into the plant genes so
that herbicides could be applied widely, saving on the labor costs of
repeated precision dousings.
The companies developing this method weren't trying to keep
it secret, but the public showed very little interest in what seemed
to be rather boring laboratory matters. But then agriculture
researchers at Monsanto took a gene derived from a bacterium and
fitted it into corn. The bacterium, Bacillus thuringiensis, usually
called Bt for short, produces a moth-killing toxin, and should thus,
the researchers reasoned, confer upon corn the ability to produce its
own pesticide against borers. This would be profitable to farmers
because they would not have to apply expensive chemical pesticides.
It would save on labor costs, too, and the lessened dependence on
chemicals could be presented as an environmentally friendly
development.
Commercial insecticidal sprays and powders made from Bt have
been around since the 1960s. They were invented in part because of
the public reaction to Rachel Carson's book Silent Spring, which had
created a strong aversion to chemical pest controls and an interest
in biological controls, which were thought to be more benign. Bt, as
a naturally occurring bacterium, became over the years one of the
most popular treatments against gypsy moth larvae and other unpopular
caterpillars. Even organic gardeners found it acceptable. But
entomologists have grumbled about Bt for years, for they knew that it
was toxic not only to the caterpillars we call bad but to those of a
great number of other moths and butterflies, too. In addition,
entomologists kept collecting evidence showing that widespread use of
Bt was encouraging the reproduction of several species of moths whose
caterpillars were resistant to it. Resistance is a genetic trait, and
Bt on its own was serving as a genetic modifier in the old
traditional way of natural selection. Bt didn't kill all the
caterpillars, just those that didn't have the genetic makeup to
resist it. Those that were resistant multiplied even faster.
Nevertheless, Monsanto developed corn laced with Bt genes,
and the crops planted from the seeds did indeed, at least
temporarily, kill off many corn borers.
Monsanto was happy. It sold a lot of seed. The growers were
happy. Fields planted with the seed showed a lower density of corn
borer infestation. But then a piece of research done by a couple of
entomologists at Cornell University was picked up by the press. The
researchers, carefully choosing one of the few insects that Americans
like, the orange and black monarch butterfly, had fed monarch
caterpillars milkweed leaves (their preferred food) that had been
dusted with pollen from the Bt-corn plants. Under laboratory
conditions, half the experimental group of caterpillars died.
Laboratory conditions are different from field conditions in that the
experimental caterpillars had no choice of what they could eat.
Entomologists were quick to point out the flaws in the experiment,
but they knew that in general, Bt was bad stuff for caterpillars of
all kinds.
The media did not have the time, space, or understanding for
nuance, and the story quickly played as FRANKENFOOD KILLS
BUTTERFLIES!!!! A suspicious public in the United States seized on
the story, joining Europeans who were already nervous about
genetically altered food. Clearly the consequences of genetic
engineering, of rearranging parts of life that were too small to see
and mysterious in their workings, were scary to many people.
Protesters dressed up in butterfly costumes. In Maine
activists used machetes to cut down a field of experimental corn in
which researchers were testing genetically induced weedkiller
resistance. Industrial food processors, fearing boycotts and loss of
revenue, vowed not to use genetically engineered foodstuffs.
It is understandable that those of us who are not biologists
have a shuddery reaction to stories about anything that is
transgenetically altered. It seems unnatural because we are
accustomed to thinking of species as categories of reality: a
bacterium is one thing and corn quite another; cows and tobacco and
fish are entirely discrete bundles of life, all politely separated
from one another . . . and from us, for goodness sake! If someone in
a white lab coat who uses a lot of Latinate words can move a gene --
something we don't quite understand but that we know is important in
making each kind of life special -- from one species to another,
well, that makes us feel penetrable and unbounded and a little
queasy. FRANKENFOOD KILLS BUTTERFLIES!!! What about us?
That reaction and that question are not surprising,
considering that many people, including policymakers, don't really
understand what molecular biologists have been up to in recent years.
Part of the reason for that lack of understanding is that the
biologists haven't done a very good job of explaining their research
in terms that nonscientists can comprehend.
But the question "Is this stuff okay for us to eat?" is as
good a beginning as any other, and it has begun to lead to other
questions, all of which should become part of a wider discussion by
the public, by scientists, and by policymakers. What happens when
genetically altered crop plants cross with wild plants? Is it a good
use of research money to insert into corn a toxin that the target
pest is already developing resistance to? You can't stop evolution --
or can you? Is this genetic pollution, and if so, what are the
implications of that? Why do we grow corn in monoculture stands that
attract diseases and pests? And why do we grow ten billion bushels of
corn a year anyway?*
Protesters in butterfly suits make for zippier television
coverage, but thoughtful biologists had their own concerns and their
own questions: Even though we know quite a bit about the locations of
at least some genes and understand some of the mechanics of genetic
biochemistry, aren't we still ignorant of the complexities of the
processes that biochemistry sets in motion? Hadn't we better learn
more about the bigger picture before we start meddling? What gives us
the right to meddle? And, perhaps the most important question:
Can "big science" (and the science in back of genetic engineering is
very big and very expensive indeed) produce good science when it is
funded, either directly or indirectly, by agribusiness,
pharmaceutical, and biotech corporations that are in a competitive
rush for patents and profit? And isn't there something unseemly about
patenting the constituents of life?
The furor over the butterflies caught many of the putative
Dr. Frankensteins by surprise, in part because they knew a lot more
about genes and molecular biology than did the rest of us. They knew,
for instance, that genes, which reside on rod-shaped chromosomes, are
found in nearly every cell of plants and animals. They contain DNA, a
big, long molecule made up of strands of an acid of the sugar-
phosphate kind. The strands are held together by substances called
bases, which are usually designated by their initial letters --
A,T,G, and C -- for adenine, thymine, guanine, and cytosine. The
bases are clubby; for chemical reasons they do their work in fixed
twosomes. A and T always go together, as do G and C. These bases bind
the acid strands chemically in a ladderlike arrangement that is then
twisted into the famous double helix.
Genes are not small bumpy things sitting on chromosomes. They
are not different kinds of things in different kinds of life. They
are not even "things" at all. They are simply the pattern in which
the bases are attached to the ladder's uprights -- A-T or T-A or G-C
or C-G -- and the sequence in which those rungs are repeated and
alternated, in functional groups of three, along a stretch of
chromosome. When someone "sequences" DNA, it is the arrangement of
those ladder rungs that is being teased out. Slight differences in
the patterned forms give us the alleles, such as the ones for brown
or blue eyes in a human being.
The arrangement of the genes is sometimes thought of as the
code, the recipe, for building life's proteins; it is, but genes
interact with one another and the organism's environment in little-
understood ways. As such they serve as switches that turn on and off
certain biochemical processes, that determine what sort of organism a
particular bit of life will be, what it will look like, and, to a
surprising degree, what it will do and how it will get on in the
world.
Each chromosome has many genes -- those patterned base pairs
of DNA strands. The numbers of chromosomes and of genes vary from
plant to plant and animal to animal. A worm whose genome (the total
number of genes an organism has in each cell) was recently sequenced
had 19,099 genes. As of this writing, the count of the human genome
is taking shape, and if the first reports are correct, we may have
somewhere between 30,000 and 40,000 genes, a mere doubling of the
number for a worm. A better understanding of those "nonfunctional"
stretches of DNA may alter that count, but nevertheless it looks to
be another reminder that all kinds of life are remarkably similar
biochemically.
For our purposes here, however, we can think about the
totality of all the genes in all the cells of a plant or animal as a
zillion little biochemical factories with switches busily turning on
and off all the time. Their sheer numbers, their activity, timing,
and interrelationships, the way they modify and change one another --
these are the processes of life itself. But no organism lives in an
isolation bubble. Other organisms and the environment in which they
find themselves affect how those genetic switches are flipped on and
off and how the processes work out. Being alive is exceedingly
complicated. The really exciting areas of microbiology these days are
those devoted to figuring out the interaction of all the parts
(mapping a genome takes time but is comparatively mechanical once you
learn how to do it, and in that sense the genes are the easy part).
An example illustrates some of the complications. Cells store energy
to use when the need arises. A plant, for instance, stores energy
from the sun, transforming it into a storable molecular form through
photosynthesis. Tapping into that energy when the plant needs it is a
twelve-step process requiring a different enzyme for each step. Each
enzyme is under the control of a separate gene, and each gene must be
switched on in the correct order and at the proper time. If that
doesn't happen, the plant can't live.
Understanding such chains of events and contingencies is much
more than the mere mapping of genes, and it gives a hint of the
difficulties facing anyone who attempts to solve an agricultural
problem by putting a gene from one organism into the genotype of
another. An acquaintance of mine -- an eminent medical researcher and
Nobel laureate -- told me privately of a further difficulty . . . and
an economic reality. His interests in genetic engineering lie not in
what we do with other animals or plants but in what we do with
ourselves -- in short, genetic "therapies" for human ills. He worries
that this notion is being oversold to the public. It is true that
some human diseases are caused by a single defective gene and might
respond to genetic treatment, but those diseases are so rare that
medical technology companies would not make a profit from treating
them. Instead, what those companies want to treat are the more
widespread and potentially profitable human ills. "But those are not
caused by a single defective gene," my friend said. "They may have a
multigenic basis that can give a person a predisposition for the
condition. However, among people with that sort of genetic profile,
some develop the condition and some never do. Perhaps it has
something to do with the way they live. There are better ways to
treat those conditions than with gene therapy, and what we need to
know more about is what makes some people vulnerable and others not."
Genes can be seen as a code written out in four letters or a
tune played on a four-note theme in triplets.* Each person, each
stalk of corn, each dog has a tune that is different from that of any
other person, stalk of corn, or dog. But within a given group of
plants or animals there is a characteristic tune -- that is, the
stretches of patterned ladder rungs are much the same within a
species. And it is surprising, at first, to see how much alike the
pattern is from one species to another. It is currently thought that
the similarity of those four-note variations of life's theme of A-T,
T-A, G-C, and C-G shows how closely related one group or species is
to another. The patterns worked in our DNA, for instance, look very
like those of chimpanzees and enough like those of dogs or cats that
genetic experiments conducted on them pertain to us. And our
molecular construction turns out to be more like that of yeasts than
anyone would have imagined fifty years ago.
This similarity is not really surprising, however, because
the evolutionary process is a ferociously conservative one. Why
reinvent the wheel? If some pattern in the DNA works, why change it?
Creation is a stingy affair. New species come about through
modification of existing sequences of the pairs of As, Ts, Gs, and Cs
and through the addition of new patterns as well. And the old
sequences can make do in new ways. For instance, flies and moths
diverged from one another about two hundred million years ago, yet
when researchers identified several genes responsible for creating
wing spots in one butterfly species (butterflies are lately
specialized moths), Junonia coenia or buckeye, they found that the
genes had the same sequence as those that are central to wing
formation in the fruit fly. The thorough study of the genetics of
fruit flies has illustrated this basic conservatism of genetic
structure. A genetic alteration that makes a fruit fly learn more
quickly can also enhance learning ability in snails or even mice,
animals that are, genetically speaking, close relatives of humans. It
has been six hundred million years since our ancestral stock and that
of a fruit fly parted company, but of the 289 mutant genes known at
this time to cause disease in humans, 177 have direct counterparts in
the fruit flies.
All the patterns that make up life on the planet are
variations on the same four-note theme, and all can be seen, in their
simplest terms, as embodying biochemical processes that are
universal, despite the complexity of the flourishes and trills.
Buried in the media stories about Bt-corn was the biological reality
of this universality, which is what makes transgenic engineering
possible. Biology has told this story many times and in many other
ways. Considering the public reaction, however, perhaps it needs to
be repeated: at its biochemical base, life, in whatever form it
takes, is pretty much the same. Corn and Bacillus thuringiensis are
not all that different, nor are we. If that is news, it is one of the
cheerfulest pieces of news I know: all of us -- corn, humans, dogs,
yeasts, fish, tobacco, and bacteria -- are fellows one to another. We
are together in this matter of life.
When biologists talk about genetic distance, they mean the
extent of variation from one kind of life to another. The new tools
of molecular biology, which are better able to examine genetic
distance, have upset old ideas about what a species is. Even though
many of us may think of "species" as a fixed and forever category of
reality, biologists know better. They regularly revise and reorder
and rename species and even debate the definition of the term.
("Genus," the first word in a scientific name, lumps together related
species. "Species," the second word, stands for uniqueness. And that
uniqueness is what biologists are increasingly having trouble
defining.) One example can suggest the kinds of puzzles biologists
are considering and why they make the shift of a gene from one kind
of life to another not quite so startling as it might seem at first.
Linda Maxson, a dean at the University of Tennessee, was
reflecting on her life as a biologist when she wrote, "I studied two
salamanders. They were taken from under the same log. They looked
identical. And the genetic distance between them was larger than that
between a human and a chimpanzee [chimpanzees are one of the apes
with whom we share 99 percent of our genes]. Such experiences lead us
to reexamine what a species is." This example is not an uncommon one
for biologists, and it makes them ask one another whether two
identical-looking cohabiting salamanders represent one or two species.
Are human beings and apes different enough to be considered
more than a single species? Of course they are, we all reply. Apes
and humans look different, do different things, and have different
capabilities. Even a child can see the difference, knows that apes
are the ones behind the bars at the zoo and people are the ones on
the outside. Children know that because we tell them so, just as we
have been told. Seeing is shaped by knowing. How would we see an ape
if we had not been told what it was?
It so happens that we have a record of such an experience
concerning the animal we call gorilla, another one of the apes with
whom we share almost complete genetic likeness. The word "gorilla" is
derived from an unknown African language as heard by the Phoenicians,
the first Mediterranean people to see the ape and the first
historical people to circumnavigate Africa. The explorer Hanno, who
sailed along its western coast, had with him some captured local
people to explain what he was seeing. A document in Greek, purported
to be a translation from a Phoenician inscription written by Hanno,
has been handed down. In part it says:
In the recess of this bay there was an island full of savage men.
There were women, too, in even greater number. They had hairy bodies
and the interpreters called them Gorillae. When we pursued them we
were unable to take any of the men; for they all escaped, by climbing
steep places and defending themselves with stones; but we took three
of the women, who bit and scratched . . . and would not follow us. So
we killed them and flayed them, and brought their skins to Carthage.
A number of writers from later times, but before the Romans
burned Carthage, reported having seen the skins of those women, who
were said to live in the south. Some even said that they were the
Amazons, those fierce women warriors.
Does the category "species" have any meaning? We still need a
word of that sort and biologists still use it, but to them the
term "species" seems much looser and a little more slippery than it
does to the public.
Botanists, especially, have long been uncomfortable with the
old species definitions, which, they believe, have been dominated by
zoological thinking, based on the interbreeding of animals to produce
offspring like the parents. Even the more recent and hedgier
definition in my biology reference book, which calls a species "the
largest unit of population within which effective gene flow occurs or
could occur," can be a problem for botanists, because the idea behind
the word "unit" doesn't always match botanical reality. For example,
cottonwoods and balsam poplars separated from a common ancestral
stock twelve million years ago, and they are recognized as separate
species. Yet they mate easily and produce fertile crosses. Or take
dandelions, which gave up pairing long ago and reproduce asexually.
They still produce pollen, but it is sterile. Genetic flow is
strictly from a single parent dandelion to its offspring, which grow
up from those fluffy seeds that waft with the breeze. Does that mean
that each maternal line of dandelions -- the ones in my yard and the
ones in yours -- is a different species? Is that a useful label? Is
it absurd? Those are just a few of the problems botanists deal with
in identifying species.
In addition, those involved in agronomy and horticulture, in
particular, are perfectly comfortable with species that are
penetrable, loose, and unbounded. Horticulturists work with plants
that are a veritable genetic hodgepodge of crosses and hybrids, and
they use the word "species" for a group of plants that are
horticulturally a unit but that have parents from different species.
To indicate this they use an × between the genus name and the species
name. Apples, which we'll meet up with in Chapter 4, go by the
scientific name of Malus × domestica. That means that the apple from
the supermarket in your brown paper lunch bag is a cross. It has the
genetic makeup, actually, not just of two disparate parents but of a
whole clutch of disparate ancestors. And if you were to plant a seed
from your lunch apple and let it grow into a tree, the fruit of that
t ree would neither look nor taste like the apple the seed came from.
All in all, the scientists in white lab coats whom the public
was calling Dr. Frankensteins were startled about the reaction to the
Bt-corn story. Many of them had their own doubts about genetic
engineering, had their own questions to ask, but they knew that
inserting a Bt gene into corn was not nearly as big a deal as
creating corn in the first place. That was a very big deal.
There is more to this story, however, than corn, which is
what caught public attention, courtesy of the monarch butterflies.
And there is more to it than food. We have created many other new
species in addition to corn. And we have fiddled with the genetic
makeup, the biological identity, of all the kinds of lives with which
we have associated. Artifice is our nature. But this has not been a
one-sided project. The plants and animals that we have made or
rearranged have given human history a push here and a nudge there and
sent it off in new directions. The story is best told by taking a
look at what a few of those plants and animals, fellow travelers of
ours, have meant to us and what we have meant to them.


Copyright © 2001 by Sue Hubbell
Illustrations copyright © 2001 by Liddy Hubbell
All rights reserved
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Table of Contents

Preface
Acknowledgments
1 Of Humanity, Tazzie the Good Dog, and Corn 1
2 Of Multicaulismania, Silkworms, and the World's First Superhighway 37
3 Of Lions, Cats, Shrinkage, and Rats 81
4 Of Apples in Heaven's Mountains and in Cow Pastures 121
Afterword 155
Appendix 161
Sources 163
Index 170
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First Chapter

Chapter One"I make thee maister," seid Robyn Hode. "Nay . . . let me be a felow," seid Litull John. — Robyn Hode and Monk, 1450 We, the namers, call our species Homo sapiens, the sapient, intelligent, wise sort of human. It is the name by which we distinguish ourselves from all other kinds of life, including those other species of the genus Homo: H. erectus, those who stood up, H. habilis, those who made stuff. They, along with the australopithecines, Cro-Magnons, and other relatives of our fine selves, managed to get themselves extinguished somewhere along the line, but we thrived and continue to do so. How wise. Tens of thousands of years of natural selection acted upon our ancestors to produce our species of humankind with our complicated, much-folded brains and clever fingers, attributes that have allowed us to spread all across the planet and even a little beyond it. In biological terms, we have a very big ecological niche. We've all seen those lists that appear in the newspapers now and again ranking animals by intelligence, giving the pig a higher grade than the horse, and the pigeon higher than either. On those lists, of course, we always come out best of all, outranking even the animals we regard as suspiciously bright, such as dolphins or apes. We win because we make the rules: we define intelligence as our kind of knowingness and dismiss any other animal knowingness as mechanical, instinctual, "hard-wired." That is the sort of verbal sleight of hand I would have been graded down for in high school debating competitions because it is an error of circularity. We define intelligence by holding up other animal minds to ours and to our way of understanding, then dismiss their ways by giving them a lesser name. Considering all the world's other intellectual follies, the pop biology represented by these lists hardly deserves to be fussed about. Nevertheless, it is heartening to note that there have always been dissenters from the conceited notion that we are the wisest animals on the planet. Margaret Cavendish, a seventeenth-century Englishwoman, a bluestocking condemned by Samuel Pepys as "ridiculous" and praised by Charles Lamb as "princely," wrote: For what man knows whether fish do not know more of the nature of water, and ebbing and flowing and the saltiness of the sea? Or whether birds do not know more of the nature and degrees of air, or the cause of tempests? Or whether worms do not know more of the nature of earth and how plants are produced? Or bees of the several sorts of juices of flower than man? . . . Man may have one way of knowledge . . . and other creatures another way, and yet other creatures' manner of way may be as intelligible and instructive to each other as Man's. As a human, I've never been flattered by my own exaltation in those intelligence-ratings lists, for I've spent my life with other animals and have come to know that they have considerable capabilities that I lack. I don't expect them to take human IQ tests, because they don't live human lives. They live dog, cat, honeybee, monkey, lion, cricket, salmon, squirrel, pigeon lives, and I'd fail their IQ tests as readily as they would fail mine. For instance, I'm no good at bones. Some years ago I shared my life with a dog named Tazzie the Good, a Belgian shepherd-black lab cross. Tazzie had all the genetically determined traits that dog breeders had drawn out over generations of inbreeding her ancestors, along with some hybridism that juggled those traits a little. More thoughtful than the average lab and a lot mellower than the average shepherd, she was obedient and devotedly loyal to me, wanting only to learn what I wanted from her and then joyfully doing it. She accepted other humans with grace and dignity. She was the definition of Good Dog. She had massive jaws that could have killed smaller creatures easily, but she used them gently because I required it. When Black Edith Kitty was a mere kitten, he would tease Tazzie into playing with him. (Like the boy in the Johnny Cash song, Black Edith has a girl's name.) Tazzie would hold him between her paws as though the cat were a living bone and delicately gnaw on him. When Black Edith had had enough of this slobbery sport, he would use his claws to rake Tazzie across her soft black nose, and she would let him go. Even compared to other dogs I have known over the years, Tazzie had extremely high bone intelligence. My husband and I have a house in a tidy neighborhood in Washington, D.C. No one there is a trashy sort of person who would strew garbage about or leave it in an uncovered bin. Yet when we took her on evening walks around the block, Tazzie would always find a bone. Not one night, not occasionally, but every night. If I'd been sent out on a treasure hunt and told that my mission was to find, in the dark, a bone in a one-block circuit of that neighborhood, I'd have failed — not just once but night after night. Tazzie was bright about bones. I am not. Tazzie was sapient in a dog's world, many aspects of which are not mine. Her world and mine overlapped at certain points — we were companions — but our skills, our intelligences, were for our own ways of life, not each other's. And those ways of life were determined by different biologies, different configurations of our DNA. Knowingness — call it intelligence, call it instinct, call it whatever you will — is always knowingness for some purpose. It is not an abstraction, not some objective gold standard. I'd never have expected Tazzie to discuss the finer points of the role of NATO in the post-Cold War world, and she accepted that I was stupid about bones, although she never quite gave up trying to interest me in the stone game. That was a game she had invented as a puppy, when we lived beside a river in the Missouri Ozarks. She would select a stone and drop it in my lap to throw for her. I'd toss it into the river, and she would leap through the air following the stone's trajectory and watch it splash and disappear. She had no interest in retrieving it. She was not that kind of a dog. Instead she'd bring a new stone to me and whine enticingly, urging me to throw it. As she aged and grew stiffer, she had as much fun simply sitting beside me and watching me throw stones. Her eyes would follow the stone's arc and its splash, and then she would whine and beg me to throw another. I always got bored with the stone game before she did, but now that she is gone I wish I'd spent more time chunking stones into the water for her and less time talking about NATO at Washington dinner parties. Some time has passed since Tazzie died in the fullness of age, but I still miss her. She was my shadow. I can still feel her chin on my knee when I am driving the car, her quiet paw on my foot as I sit writing. She was a very present animal. All the years I've spent hanging out with other animals and the zoologists who study them have led me to think that it is arrogant and even silly of us to name ourselves for our intelligence. But we have another preeminent trait, one that we are good at beyond all other animals, and that is our ability to modify the world to make it nice for ourselves. A more accurate name for us might be Homo mutans, the human who changes things. We do not accept what we find. We use that brain and those fingers, with the extensions we've made for them, to alter, build, excavate, extend, recombine, fuss, and fiddle to make the world comfortable and more interesting to us. Other animals modify their particular worlds, of course, to the extent that they are able. Honeybees harvest plant sap and process it into a glue to chink their hives against winter drafts. Bowerbirds gather up fresh flowers to display in the competition for mates. Caddis fly larvae make protective shelters out of grains of sand. Last winter a mouse stole all the little wooden vegetables from a dollhouse I have for grandchildren. I do not understand the mouse's purpose: when I pulled open one of my desk drawers I found within it a mouse nest made of pulled chair stuffing surrounded by the tiny wooden carrots, cabbages, and rutabagas. Both chimpanzees and certain insect-eating finches use twigs to stir up ants and other bugs from their nests so that they are easier to catch and eat. I remember a bold tufted titmouse who made life uncomfortable for a friend of mine by making unrelenting, swooping passes over his curly head of hair and then, with great daring, pulling out several hairs. We watched as it skillfully wove them into a nest. Tinkering with existing circumstances and materials is characteristic of life in all its forms, but we humans have better biological equipment for this purpose. And as a result we are more thoroughgoing. We are the fiddlingest animal the world has ever seen. Now that we are six billion in number and have more powerful tools than ever to modify the planet, we are starting to wonder whether we are fiddling so much that we and other kinds of life may not be able to continue living on it. We are finally beginning to ask where all this fiddling is taking us. Impatient environmentalists sometimes get discouraged and think we aren't getting anywhere, but we've only recently become aware of the problem and have just commenced asking questions. It is only about one hundred years since we filled up the habitable earth and far fewer since we realized that there are too many of us and only just now that we are attending to the fact that we do not have an entirely happy effect on other kinds of life. We will have to ask a lot of questions before we can figure out how to frame those that might help us solve the problems we have caused. And we are just beginning to pose the necessary questions about limits: limits to our own numbers, limits to the extension of human life into prolonged senescence, limits to our consumption and exploitation. These are ferociously difficult questions because our biological design is to increase willy-nilly and to grab whatever is available (as it is for any species). But we are developing a modicum of self-awareness and a struggling, if not always successful, objectivity, and that makes me optimistic about our kind. It may be that none of us alive today will be around long enough to see solutions to the problems of limits, but I think our descendants will find them. And when they do, we will deserve to be called sapiens. One of the questions we've asked as we began to consider our impact on the world runs something like this: Weren't there — somewhere, sometime — pure and unspoiled people who made better arrangements with the world than we have? Aren't today's "primitive" people rather like that? The answer to both questions is, probably not. As Jared Diamond, the physiologist who has studied and thought about people in out-of-the-way places, often points out, people everywhere are as exploitative of the resources they find as their technology and numbers permit. It is easy to believe that those who are fewer in number somehow have better intentions toward the planet than we. That river where I used to chuck stones for Tazzie is named the Jack's Fork. Part of the first National Scenic Riverway designated by the U.S. Park Service, it runs through rugged land in the Ozarks of southern Missouri. While I lived there I came to know a federal archaeologist who had excavated along its banks and had found that a long time ago — I no longer remember the dates — there had been densely populated Indian villages along the river. The Indians had cleared the land and farmed the thin soil. Farming in the Ozarks is a heartbreaking business, as the white settlers were to discover. The land is too steep and the soil too thin and poor for good crops. The archaeologist had found artifacts — pots, bowls, baskets, and arrow points — in the remains of the Indian houses. The oldest artifacts were made with expertness and grace, but the most recent ones lacked both qualities. He had arranged a collection of arrow points by date of making, and they became cruder and cruder over time; the baskets and pots also became increasingly rougher and coarser, as if they had been made by a people who had grown sad and ineffectual. There were signs that in the end the people had left quickly. The archaeologist suspected that disease of some kind had swept through the towns (as evidence suggests happened elsewhere in North America) and that those left were too few or too weak to defend themselves. Dust and dead leaves would have blown through the empty villages (some of which had been burned). Gradually over the years, their garbage dumps and home debris, their tools and pots, were covered and buried under accumulating soil. Weeds crept into the fields where they had grown corn, a crop Europeans had yet to learn of. Low bushes, then trees followed. The Jack's Fork, no longer silty from farmland runoff, ran clear. Slowly the Ozarks took on the character it had when Americans of European descent found it in the 1800s, a wild place full of big pine, oak, walnut, cedar, and hickory trees, clear streams, and wild animals. There were no signs left to tell that it had once been home to many people who had used everything they found there. The story was repeated in many parts of the Americas. Peoples from the Mayans, with their high culture, to the Mound Builders increased in numbers, altering and using whatever they could, until life became precarious for one reason or another and their ways failed them. Their descendants, few in number, lived on in poorer circumstances. The Indians whom the Europeans first met when they came to North America, even if they were descendants of people who had known greater amenities, had more skill at living from the land than the Europeans, who were mainly city folk with no knowledge of fishing, hunting, or farming. The native plants — wild berries, nuts, pawpaws, and the like — were not enough to sustain them, and they did not even recognize some of what was available as food. Lobsters, for instance, they regarded as offal. In 1622 William Bradford, one of the early Pilgrim dissidents who had come to these shores on the Mayflower, wrote a letter describing the settlers' privations, using as an example their humiliation and sadness when, on the occasion of receiving visitors, "the sole dish they could present their friends with was lobster." Some settlers starved, but some took lessons from the Indians, who were farming several staples — sweet potatoes, squash, and corn — unknown to the Europeans. They quickly learned how to grow them. None of these crops was native to North America; they had all come from the New World tropics and had been cultivated and improved over the centuries. Of the three, corn would become the most important foodstuff that the New World gave to the Old. Corn, like squash and sweet potatoes, was the result of the sort of fiddling with materials at hand that has taken place all over the world and is now called agriculture: the human creation of new botanical species whose genetic structures are distinct from those of their wild ancestors. Corn is basically a grass, a member of a large family of plants that includes not only the green kind growing as lawns but also bamboo, rice, and sugar cane. Corn betrays its origins as a neotropical grass by a peculiarity of leaf anatomy — the clustering of photosynthetic cells, the engines that turn sunlight into plant energy — around the leaf's midrib. This configuration is typical of plants growing in hot, dry places. In temperate-zone plants, by contrast, the photosynthetic cells are ranged around the leaf veins, where they can respire in cooler temperatures. The earliest farmers selected certain plants, some of which were mutants, that produced unusually good things to eat and saved their seeds to plant again. They planted the selected seeds, cosseted the plants that grew from them, and repeated the process again and again until they had created crops that were dependable and productive. Those traits are genetically determined, and thus those early farmers were rearranging genes, even though they did not know what genes were. The ancestor of corn is lost in some pre-Incan, pre-Mayan, pre-Aztec past, but a respectable hypothesis that accounts for many aspects of the corn plant has been put forward by Hugh H. Iltis, a botanist at the University of Wisconsin, who has spent much of his research life thinking about the history of corn. He conjectures that corn originated 7,500 years ago in Central America as a botanical anomaly when an existing grass (probably quite like corn's nearest modern relative, called teosinte) had its male parts hijacked by its female parts. As a result, the plant produced very large seeds growing against a protective sheath (which would in time become a husk). They looked more like tiny kernels of corn than like ordinary grass seeds. Such a transformation may sound bizarre, and it is uncommon, but it is an expression of relic bisexuality that sometimes does take place in plants during periods of stress — during an unusually wet rainy season, for instance. And that sort of stress is just what may have started corn on its way, according to Iltis. He adds that in the wild, when the weather pattern returns to normal, this relic bisexuality would disappear. Strictly speaking, these proto-corn plants were, as Iltis phrases it, a genetic "catastrophe," hoarders of female energy in the form of seed. But Indian farmers kept the seeds and planted them in rows, which were more convenient to tend and weed than scattered plants. They must have continued to select and plant seeds from plants that grew straighter and sprawled less than the original grasslike forms, because the plants genetically inclined to slim tallness were easier to farm. In the course of time this wonderful new crop plant was carried northward. The earliest archaeological evidence of corn in North America is about two or three thousand years old. Tiny kernels of popcorn were found in a cave in New Mexico along with tools and other signs that a family had lived there. The kernels, the discoverers found, could still be popped. Those innovative early farmers would have been quickly encouraged in their agricultural efforts because the food value of corn rapidly improves with selective planting, as was demonstrated in an experiment conducted at the University of Illinois. The agronomists selected and planted corn seeds that were slightly higher in oil content — a genetically determined trait — than the rest of the seeds. They repeated the process after each harvest, always saving the seed with the highest oil content for replanting. When they graphed the results, they found a steady upward curve that showed no sign of leveling off when they brought the experiment to a close after fifty generations. Even though those early farmers couldn't reach into the grass- becoming-a-corn-plant and fiddle with its genes as we can today, they could see and taste the expression of its genes. Biologists call the visible package of expressed genes the phenotype. When you look at me or I look at you, we see a phenotype. The stalk of corn, with its coarse, bladelike leaves, its silk, its corn kernels neatly and greenly wrapped, is the phenotype of its expressed genes. Not all of its genes are expressed, nor are all of yours or mine. All of us — humans, Tazzie the Good Dog, a corn plant — carry a unique genetic profile in our cells. That profile includes both expressed genes and ones that are not expressed: genes that are nonfunctional (as far as we can tell) and those that are recessive and thus masked by the dominant form of the same gene. All of those genes — unfunctional, expressed, and unexpressed, dominant and recessive — make up an individual's genotype. Genotype. Phenotype. It oversimplifies, but it helps to think of a package delivered by the UPS man. The package is the phenotype. You can tell something about what is inside by the size of the box, its weight, and the way it does or does not rattle. But you can't tell exactly what is inside until you open it. The contents are the genotype. The individual genes for any plant or animal can take different alternative forms, which are called alleles. In sexual pairing, genetic material from both parents is shared to make up a new individual. In humans, for instance, brown eye color is controlled by a dominant allele and blue eye color by a recessive one. Two brown-eyed parents may each carry a blue eye-color allele, and if, in the genetic sorting that takes place in mating, their baby receives both blue-eyed alleles, she will have blue eyes. Their baby has a phenotype all her own. It was only about one hundred and fifty years ago that the Austrian cleric Gregor Mendel began to elucidate this process, and it is startling to realize that the word "gene," so much a part of contemporary vocabulary, was coined in its modern sense only in 1909 (by Wilhelm Johannsen, a Danish agronomist). Inheritance, and hence genetics, can be complicated for a number of biological reasons, and when Mendel began his work on what he called "factors of inheritance," he had the bad luck to choose as his first experimental model an animal that featured some of those complications: the honeybee. His experiments ended with confusing results, but fortunately he was a persistent man. Drawing on his interest in plant hybridizing, Mendel chose peas as his next experimental model. And peas, although Mendel could not have known it beforehand, are, fortunately, simpler genetically. With his pea experiments he demonstrated the emergence of recessive characteristics. Peas with red flowers and long stems carry dominant alleles of certain genes, and when they are crossed with white- flowered, short-stemmed peas, which have recessive alleles of the same genes, the first generation of plants all has red flowers and long stems. But when that first generation is intermated, the white flowers and short stems reappear in the next generation. And, what is more, they reappear in a tidy, predictable ratio. (Some suspect that his results were a little too good, that he fudged a little.) Later Mendel tried to test his conclusions on other plants and, once again, was left with more questions than answers and grew discouraged. A basic understanding of how recessive traits are expressed, along with a new understanding of some aspects of inheritance that bewildered Mendel, has become the stock in trade of horticulturists, animal breeders, and agronomists. In the wild, natural selection nudges and prunes the genotypes of plants and animals toward toughness, vigor, and successful reproduction and in that process maintains within the population a characteristic ratio of allelic frequency. But when artificial selection takes over, the story changes. One of the tricks that breeders of plants and animals had learned long before Mendel was that close inbreeding, although it might decrease vigor, could bring out traits we liked. Close matings to bring out recessive alleles and preserve mutations have created dogs with floppy ears, cats with no hair, and pigs with extra loin-end vertebrae and hence extra pork chops. Those attributes are ones that we fancy, even if the wild, harsh world does not. Wild grass, corn's ancestor, shed its seeds abundantly and freely. Biologists think of corn as a "botanical monster," for its seeds, wrapped in unnaturally tight husks, do not disperse and plant themselves. And, even if a husked ear falls and is buried in the soil, the young shoots growing from the kernels die because they are overcrowded. But those tightly clustered kernels in their waterproof husks are just what we want. Never mind that corn does not replant itself. We will plant it, just as we will take care of its lack of vigor, its vulnerability to pests and diseases. Corn is a man-made plant, and in return for the good features we have drawn from its genotype, we will take care of it. If little green men were to swoop down from the sky one day and kidnap all of humanity in their spaceships, our descendants — brought back to the planet after five thousand years of good behavior — would find no corn. Corn has to have human beings if it is to live and grow and reproduce. After those first grateful European settlers learned how to grow corn, it soon became a sustaining crop. They could feed it to livestock or eat it directly. They could grind it into meal, which could be boiled into mush or fried into journey cake. A mash prepared from corn made an Everyman's tipple. Over the several hundred years since we began to grow it, new varieties of corn have been developed to suit new purposes. As anyone who drives through the Midwest in summertime might suspect, corn is the number-one grain grown in the United States. Just under ten billion bushels of it are grown every year — three times as much as its nearest rival, soybeans. Most of this harvest isn't the sweet corn sold at Mr. and Mrs. Smith's roadside stand. It is corn for animal feed, corn for ethanol, corn for starch, and corn for syrups to feed the world's seemingly insatiable taste for sweet snack foods and drinks. That summertime driver can't help but notice how much growing room corn takes up: the fields look endless. The United States is the world's biggest producer of corn and devotes more acreage to it — more than seventy-two million acres — than any other country does. But extensive stands of corn (or any other plant) are a wonderfully attractive lure for pesty creatures and diseases, which sustain themselves and multiply on its bounty. Corn borers are corn growers' most worrisome insect, hard to treat because they penetrate the plant and do not stay long on the outside, where they can be conveniently sprayed to death. They are the caterpillars of a modest-looking gray-brown moth, Ostrinia nubilalis, and they tunnel through the cornstalks and prop roots, even infesting the tassels of the ears. The moth came from Europe, where it dines on other plants as well and is less of a pest, not only because less corn is grown there but also because it has been there for a very long time and is kept in check by a variety of diseases and predators with which it has evolved. In North America the caterpillars found corn much to their liking and thrived in the absence of predators. Over the years, agronomists have found a number of ways to deal with corn borers. Birds will eat the moths' eggs as well as the caterpillars, and when corn is grown in small plots with hedgerows around them, birds can find places to nest nearby. A variety of insecticidal sprays, including some that are illegal in the United States today, such as DDT, were used with modest success. Some cultural practices, such as plowing and disposing of infested stalks, helped when farms had enough hands to do those chores. Certain strains of corn show more resistance to borers than others, and for a while agronomists worked at developing that resistance genetically. They also imported, from Europe, disease organisms and predators that attack corn borers with fair success. All of those practices are more helpful for small stands of corn than for large ones. But small plantings are more labor-intensive than current agribusiness profit margins allow. Our talent for fiddling with materials to hand — making up corn in the first place, concentrating it in monoculture stands, and inadvertently bringing corn borers to it — created a problem. Homo mutans is good at finding a solution to a specific, limited problem by bringing in another technological fix. Up until half a century ago, we solved problems of this sort genetically by crossbreeding — some of it pretty fancy, to be sure — and by manipulating the reproductive process to bring out the expression of genes in which we were interested. We may have had a more sophisticated understanding of the genetic determination of characteristics than the Indian farmers who developed corn those thousands of years ago, but essentially we were continuing to do what they had done: taking stock of the phenotype. But in the past fifty years, as the structure of DNA has been elucidated and molecular biologists have learned what happens when gene switches are flipped, biotechnicians have learned how to reach inside cells and fiddle directly with those processes. The fields of study that have grown from this new understanding are exciting and use a lot of shiny, expensive machinery. They have drawn many of our best young biologists, because it is easy to get funding for their work from the agribusiness and pharmaceutical corporations that stand to gain from their discoveries. What we have learned to call recombinant DNA technology (which is, essentially, reaching inside and fiddling with the genes directly) has begun to produce profitable substances, including hormones such as insulin for diabetics. That invention was helpful for humans and lucrative for the corporations. The agricultural biotech companies used the same techniques to produce bovine growth hormone. BGH obviously provides financial benefits not only to its manufacturers but to industrial dairies (more milk from fewer cows), despite the physiological price paid by the particular bovines into whom it is injected. Biotechnology in the past several decades has been able to slip interesting genes from one organism into the genotype of another. In crop plants and animals, this produces changes much more precisely, directly, and quickly than does crossbreeding. And this form of fiddling we have learned to call transgenic engineering. A bacterium, Agrobacterium tumefaciens (which in its original host causes the disease crown gall), was used to shoehorn into the genotype of tobacco plants certain genes that would provide resistance to diseases, insects, and herbicides. That worked so nicely that the same method has been used with other crop plants. Biotechnicians learned to put extra growth genes into fish farmed in captivity to make them grow faster and turn a quicker profit. They put a moth gene into apples to produce a degree of resistance to fire blight. Monsanto, one of the agribusiness giants, is developing a corn plant that may produce plastics, even pharmaceuticals, courtesy of a cluster of bacterial genes. Using a similar method, the seed company Asgrow has developed squash seeds that are resistant to disease. By 1999 half of the soybeans growing in U.S. fields had been genetically rejiggered to withstand weedkillers. Until recently, all of these developments sounded like good news to many people, yet another happy result of sparkling new technologies. To agronomists, developing plants with a genetic resistance to weedkillers seemed a particularly forward-thinking thing to do. A couple of generations ago, plowing and cultivating kept the weeds in farmers' fields in check. But those techniques kill earthworms, which help increase the soil's fertility. Plowing and cultivating also make the soil fluffy and loose so that the wind can blow it away, as it did in the Dust Bowl drought in the 1930s. In the aftermath of that disaster, agronomists invented the way most agriculture is practiced today, the no-till method. With the plow and the tiller on the scrap heap, earthworms thrive, the soil stays in place, and less labor is required to grow crops. But when soil is not plowed and tilled, weeds proliferate, choking out crop plants. As a result, weedkillers — herbicides — have replaced cultivation. But weedkillers are not selective, and unless care is taken, they can kill crop plants, too. The agronomists reasoned that it would be useful to put weedkiller resistance directly into the plant genes so that herbicides could be applied widely, saving on the labor costs of repeated precision dousings. The companies developing this method weren't trying to keep it secret, but the public showed very little interest in what seemed to be rather boring laboratory matters. But then agriculture researchers at Monsanto took a gene derived from a bacterium and fitted it into corn. The bacterium, Bacillus thuringiensis, usually called Bt for short, produces a moth-killing toxin, and should thus, the researchers reasoned, confer upon corn the ability to produce its own pesticide against borers. This would be profitable to farmers because they would not have to apply expensive chemical pesticides. It would save on labor costs, too, and the lessened dependence on chemicals could be presented as an environmentally friendly development. Commercial insecticidal sprays and powders made from Bt have been around since the 1960s. They were invented in part because of the public reaction to Rachel Carson's book Silent Spring, which had created a strong aversion to chemical pest controls and an interest in biological controls, which were thought to be more benign. Bt, as a naturally occurring bacterium, became over the years one of the most popular treatments against gypsy moth larvae and other unpopular caterpillars. Even organic gardeners found it acceptable. But entomologists have grumbled about Bt for years, for they knew that it was toxic not only to the caterpillars we call bad but to those of a great number of other moths and butterflies, too. In addition, entomologists kept collecting evidence showing that widespread use of Bt was encouraging the reproduction of several species of moths whose caterpillars were resistant to it. Resistance is a genetic trait, and Bt on its own was serving as a genetic modifier in the old traditional way of natural selection. Bt didn't kill all the caterpillars, just those that didn't have the genetic makeup to resist it. Those that were resistant multiplied even faster. Nevertheless, Monsanto developed corn laced with Bt genes, and the crops planted from the seeds did indeed, at least temporarily, kill off many corn borers. Monsanto was happy. It sold a lot of seed. The growers were happy. Fields planted with the seed showed a lower density of corn borer infestation. But then a piece of research done by a couple of entomologists at Cornell University was picked up by the press. The researchers, carefully choosing one of the few insects that Americans like, the orange and black monarch butterfly, had fed monarch caterpillars milkweed leaves (their preferred food) that had been dusted with pollen from the Bt-corn plants. Under laboratory conditions, half the experimental group of caterpillars died. Laboratory conditions are different from field conditions in that the experimental caterpillars had no choice of what they could eat. Entomologists were quick to point out the flaws in the experiment, but they knew that in general, Bt was bad stuff for caterpillars of all kinds. The media did not have the time, space, or understanding for nuance, and the story quickly played as FRANKENFOOD KILLS BUTTERFLIES!!!! A suspicious public in the United States seized on the story, joining Europeans who were already nervous about genetically altered food. Clearly the consequences of genetic engineering, of rearranging parts of life that were too small to see and mysterious in their workings, were scary to many people. Protesters dressed up in butterfly costumes. In Maine activists used machetes to cut down a field of experimental corn in which researchers were testing genetically induced weedkiller resistance. Industrial food processors, fearing boycotts and loss of revenue, vowed not to use genetically engineered foodstuffs. It is understandable that those of us who are not biologists have a shuddery reaction to stories about anything that is transgenetically altered. It seems unnatural because we are accustomed to thinking of species as categories of reality: a bacterium is one thing and corn quite another; cows and tobacco and fish are entirely discrete bundles of life, all politely separated from one another . . . and from us, for goodness sake! If someone in a white lab coat who uses a lot of Latinate words can move a gene — something we don't quite understand but that we know is important in making each kind of life special — from one species to another, well, that makes us feel penetrable and unbounded and a little queasy. FRANKENFOOD KILLS BUTTERFLIES!!! What about us? That reaction and that question are not surprising, considering that many people, including policymakers, don't really understand what molecular biologists have been up to in recent years. Part of the reason for that lack of understanding is that the biologists haven't done a very good job of explaining their research in terms that nonscientists can comprehend. But the question "Is this stuff okay for us to eat?" is as good a beginning as any other, and it has begun to lead to other questions, all of which should become part of a wider discussion by the public, by scientists, and by policymakers. What happens when genetically altered crop plants cross with wild plants? Is it a good use of research money to insert into corn a toxin that the target pest is already developing resistance to? You can't stop evolution — or can you? Is this genetic pollution, and if so, what are the implications of that? Why do we grow corn in monoculture stands that attract diseases and pests? And why do we grow ten billion bushels of corn a year anyway?* Protesters in butterfly suits make for zippier television coverage, but thoughtful biologists had their own concerns and their own questions: Even though we know quite a bit about the locations of at least some genes and understand some of the mechanics of genetic biochemistry, aren't we still ignorant of the complexities of the processes that biochemistry sets in motion? Hadn't we better learn more about the bigger picture before we start meddling? What gives us the right to meddle? And, perhaps the most important question: Can "big science" (and the science in back of genetic engineering is very big and very expensive indeed) produce good science when it is funded, either directly or indirectly, by agribusiness, pharmaceutical, and biotech corporations that are in a competitive rush for patents and profit? And isn't there something unseemly about patenting the constituents of life? The furor over the butterflies caught many of the putative Dr. Frankensteins by surprise, in part because they knew a lot more about genes and molecular biology than did the rest of us. They knew, for instance, that genes, which reside on rod-shaped chromosomes, are found in nearly every cell of plants and animals. They contain DNA, a big, long molecule made up of strands of an acid of the sugar- phosphate kind. The strands are held together by substances called bases, which are usually designated by their initial letters — A,T,G, and C — for adenine, thymine, guanine, and cytosine. The bases are clubby; for chemical reasons they do their work in fixed twosomes. A and T always go together, as do G and C. These bases bind the acid strands chemically in a ladderlike arrangement that is then twisted into the famous double helix. Genes are not small bumpy things sitting on chromosomes. They are not different kinds of things in different kinds of life. They are not even "things" at all. They are simply the pattern in which the bases are attached to the ladder's uprights — A-T or T-A or G-C or C-G — and the sequence in which those rungs are repeated and alternated, in functional groups of three, along a stretch of chromosome. When someone "sequences" DNA, it is the arrangement of those ladder rungs that is being teased out. Slight differences in the patterned forms give us the alleles, such as the ones for brown or blue eyes in a human being. The arrangement of the genes is sometimes thought of as the code, the recipe, for building life's proteins; it is, but genes interact with one another and the organism's environment in little- understood ways. As such they serve as switches that turn on and off certain biochemical processes, that determine what sort of organism a particular bit of life will be, what it will look like, and, to a surprising degree, what it will do and how it will get on in the world. Each chromosome has many genes — those patterned base pairs of DNA strands. The numbers of chromosomes and of genes vary from plant to plant and animal to animal. A worm whose genome (the total number of genes an organism has in each cell) was recently sequenced had 19,099 genes. As of this writing, the count of the human genome is taking shape, and if the first reports are correct, we may have somewhere between 30,000 and 40,000 genes, a mere doubling of the number for a worm. A better understanding of those "nonfunctional" stretches of DNA may alter that count, but nevertheless it looks to be another reminder that all kinds of life are remarkably similar biochemically. For our purposes here, however, we can think about the totality of all the genes in all the cells of a plant or animal as a zillion little biochemical factories with switches busily turning on and off all the time. Their sheer numbers, their activity, timing, and interrelationships, the way they modify and change one another — these are the processes of life itself. But no organism lives in an isolation bubble. Other organisms and the environment in which they find themselves affect how those genetic switches are flipped on and off and how the processes work out. Being alive is exceedingly complicated. The really exciting areas of microbiology these days are those devoted to figuring out the interaction of all the parts (mapping a genome takes time but is comparatively mechanical once you learn how to do it, and in that sense the genes are the easy part). An example illustrates some of the complications. Cells store energy to use when the need arises. A plant, for instance, stores energy from the sun, transforming it into a storable molecular form through photosynthesis. Tapping into that energy when the plant needs it is a twelve-step process requiring a different enzyme for each step. Each enzyme is under the control of a separate gene, and each gene must be switched on in the correct order and at the proper time. If that doesn't happen, the plant can't live. Understanding such chains of events and contingencies is much more than the mere mapping of genes, and it gives a hint of the difficulties facing anyone who attempts to solve an agricultural problem by putting a gene from one organism into the genotype of another. An acquaintance of mine — an eminent medical researcher and Nobel laureate — told me privately of a further difficulty . . . and an economic reality. His interests in genetic engineering lie not in what we do with other animals or plants but in what we do with ourselves — in short, genetic "therapies" for human ills. He worries that this notion is being oversold to the public. It is true that some human diseases are caused by a single defective gene and might respond to genetic treatment, but those diseases are so rare that medical technology companies would not make a profit from treating them. Instead, what those companies want to treat are the more widespread and potentially profitable human ills. "But those are not caused by a single defective gene," my friend said. "They may have a multigenic basis that can give a person a predisposition for the condition. However, among people with that sort of genetic profile, some develop the condition and some never do. Perhaps it has something to do with the way they live. There are better ways to treat those conditions than with gene therapy, and what we need to know more about is what makes some people vulnerable and others not." Genes can be seen as a code written out in four letters or a tune played on a four-note theme in triplets.* Each person, each stalk of corn, each dog has a tune that is different from that of any other person, stalk of corn, or dog. But within a given group of plants or animals there is a characteristic tune — that is, the stretches of patterned ladder rungs are much the same within a species. And it is surprising, at first, to see how much alike the pattern is from one species to another. It is currently thought that the similarity of those four-note variations of life's theme of A-T, T-A, G-C, and C-G shows how closely related one group or species is to another. The patterns worked in our DNA, for instance, look very like those of chimpanzees and enough like those of dogs or cats that genetic experiments conducted on them pertain to us. And our molecular construction turns out to be more like that of yeasts than anyone would have imagined fifty years ago. This similarity is not really surprising, however, because the evolutionary process is a ferociously conservative one. Why reinvent the wheel? If some pattern in the DNA works, why change it? Creation is a stingy affair. New species come about through modification of existing sequences of the pairs of As, Ts, Gs, and Cs and through the addition of new patterns as well. And the old sequences can make do in new ways. For instance, flies and moths diverged from one another about two hundred million years ago, yet when researchers identified several genes responsible for creating wing spots in one butterfly species (butterflies are lately specialized moths), Junonia coenia or buckeye, they found that the genes had the same sequence as those that are central to wing formation in the fruit fly. The thorough study of the genetics of fruit flies has illustrated this basic conservatism of genetic structure. A genetic alteration that makes a fruit fly learn more quickly can also enhance learning ability in snails or even mice, animals that are, genetically speaking, close relatives of humans. It has been six hundred million years since our ancestral stock and that of a fruit fly parted company, but of the 289 mutant genes known at this time to cause disease in humans, 177 have direct counterparts in the fruit flies. All the patterns that make up life on the planet are variations on the same four-note theme, and all can be seen, in their simplest terms, as embodying biochemical processes that are universal, despite the complexity of the flourishes and trills. Buried in the media stories about Bt-corn was the biological reality of this universality, which is what makes transgenic engineering possible. Biology has told this story many times and in many other ways. Considering the public reaction, however, perhaps it needs to be repeated: at its biochemical base, life, in whatever form it takes, is pretty much the same. Corn and Bacillus thuringiensis are not all that different, nor are we. If that is news, it is one of the cheerfulest pieces of news I know: all of us — corn, humans, dogs, yeasts, fish, tobacco, and bacteria — are fellows one to another. We are together in this matter of life. When biologists talk about genetic distance, they mean the extent of variation from one kind of life to another. The new tools of molecular biology, which are better able to examine genetic distance, have upset old ideas about what a species is. Even though many of us may think of "species" as a fixed and forever category of reality, biologists know better. They regularly revise and reorder and rename species and even debate the definition of the term. ("Genus," the first word in a scientific name, lumps together related species. "Species," the second word, stands for uniqueness. And that uniqueness is what biologists are increasingly having trouble defining.) One example can suggest the kinds of puzzles biologists are considering and why they make the shift of a gene from one kind of life to another not quite so startling as it might seem at first. Linda Maxson, a dean at the University of Tennessee, was reflecting on her life as a biologist when she wrote, "I studied two salamanders. They were taken from under the same log. They looked identical. And the genetic distance between them was larger than that between a human and a chimpanzee [chimpanzees are one of the apes with whom we share 99 percent of our genes]. Such experiences lead us to reexamine what a species is." This example is not an uncommon one for biologists, and it makes them ask one another whether two identical-looking cohabiting salamanders represent one or two species. Are human beings and apes different enough to be considered more than a single species? Of course they are, we all reply. Apes and humans look different, do different things, and have different capabilities. Even a child can see the difference, knows that apes are the ones behind the bars at the zoo and people are the ones on the outside. Children know that because we tell them so, just as we have been told. Seeing is shaped by knowing. How would we see an ape if we had not been told what it was? It so happens that we have a record of such an experience concerning the animal we call gorilla, another one of the apes with whom we share almost complete genetic likeness. The word "gorilla" is derived from an unknown African language as heard by the Phoenicians, the first Mediterranean people to see the ape and the first historical people to circumnavigate Africa. The explorer Hanno, who sailed along its western coast, had with him some captured local people to explain what he was seeing. A document in Greek, purported to be a translation from a Phoenician inscription written by Hanno, has been handed down. In part it says: In the recess of this bay there was an island full of savage men. There were women, too, in even greater number. They had hairy bodies and the interpreters called them Gorillae. When we pursued them we were unable to take any of the men; for they all escaped, by climbing steep places and defending themselves with stones; but we took three of the women, who bit and scratched . . . and would not follow us. So we killed them and flayed them, and brought their skins to Carthage. A number of writers from later times, but before the Romans burned Carthage, reported having seen the skins of those women, who were said to live in the south. Some even said that they were the Amazons, those fierce women warriors. Does the category "species" have any meaning? We still need a word of that sort and biologists still use it, but to them the term "species" seems much looser and a little more slippery than it does to the public. Botanists, especially, have long been uncomfortable with the old species definitions, which, they believe, have been dominated by zoological thinking, based on the interbreeding of animals to produce offspring like the parents. Even the more recent and hedgier definition in my biology reference book, which calls a species "the largest unit of population within which effective gene flow occurs or could occur," can be a problem for botanists, because the idea behind the word "unit" doesn't always match botanical reality. For example, cottonwoods and balsam poplars separated from a common ancestral stock twelve million years ago, and they are recognized as separate species. Yet they mate easily and produce fertile crosses. Or take dandelions, which gave up pairing long ago and reproduce asexually. They still produce pollen, but it is sterile. Genetic flow is strictly from a single parent dandelion to its offspring, which grow up from those fluffy seeds that waft with the breeze. Does that mean that each maternal line of dandelions — the ones in my yard and the ones in yours — is a different species? Is that a useful label? Is it absurd? Those are just a few of the problems botanists deal with in identifying species. In addition, those involved in agronomy and horticulture, in particular, are perfectly comfortable with species that are penetrable, loose, and unbounded. Horticulturists work with plants that are a veritable genetic hodgepodge of crosses and hybrids, and they use the word "species" for a group of plants that are horticulturally a unit but that have parents from different species. To indicate this they use an × between the genus name and the species name. Apples, which we'll meet up with in Chapter 4, go by the scientific name of Malus × domestica. That means that the apple from the supermarket in your brown paper lunch bag is a cross. It has the genetic makeup, actually, not just of two disparate parents but of a whole clutch of disparate ancestors. And if you were to plant a seed from your lunch apple and let it grow into a tree, the fruit of that tree would neither look nor taste like the apple the seed came from. All in all, the scientists in white lab coats whom the public was calling Dr. Frankensteins were startled about the reaction to the Bt-corn story. Many of them had their own doubts about genetic engineering, had their own questions to ask, but they knew that inserting a Bt gene into corn was not nearly as big a deal as creating corn in the first place. That was a very big deal. There is more to this story, however, than corn, which is what caught public attention, courtesy of the monarch butterflies. And there is more to it than food. We have created many other new species in addition to corn. And we have fiddled with the genetic makeup, the biological identity, of all the kinds of lives with which we have associated. Artifice is our nature. But this has not been a one-sided project. The plants and animals that we have made or rearranged have given human history a push here and a nudge there and sent it off in new directions. The story is best told by taking a look at what a few of those plants and animals, fellow travelers of ours, have meant to us and what we have meant to them. Copyright © 2001 by Sue Hubbell Illustrations copyright © 2001 by Liddy Hubbell All rights reserved
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