- Shopping Bag ( 0 items )
In a world supposedly governed by ruthless survival of the fittest, why do we see acts of goodness in both animals and humans? This problem plagued Charles Darwin in the 1850s as he developed his theory of evolution through natural selection. Indeed, Darwin worried that the goodness he observed in nature could be the Achilles heel of his theory. Ever since then, scientists and other thinkers have engaged in a fierce debate about the origins of goodness that has dragged politics, philosophy, and religion into what...
In a world supposedly governed by ruthless survival of the fittest, why do we see acts of goodness in both animals and humans? This problem plagued Charles Darwin in the 1850s as he developed his theory of evolution through natural selection. Indeed, Darwin worried that the goodness he observed in nature could be the Achilles heel of his theory. Ever since then, scientists and other thinkers have engaged in a fierce debate about the origins of goodness that has dragged politics, philosophy, and religion into what remains a major question for evolutionary biology.
The Altruism Equation traces the history of this debate from Darwin to the present through an extraordinary cast of characters-from the Russian prince Petr Kropotkin, who wanted to base society on altruism, to the brilliant biologist George Price, who fell into poverty and succumbed to suicide as he obsessed over the problem. In a final surprising turn, William Hamilton, the scientist who came up with the equation that reduced altruism to the cold language of natural selection, desperately hoped that his theory did not apply to humans.
Hamilton's Rule, which states that relatives are worth helping in direct proportion to their blood relatedness, is as fundamental to evolutionary biology as Newton's laws of motion are to physics. But even today, decades after its formulation, Hamilton's Rule is still hotly debated among those who cannot accept that goodness can be explained by a simple mathematical formula. For the first time, Lee Alan Dugatkin brings to life the people, the issues, and the passions that have surrounded the altruism debate. Readers will be swept along by this fast-paced tale of history, biography, and scientific discovery.
While writing On the Origin of Species in the late 1850s, Charles Darwin was unencumbered by the strict editorial rules that apply to scientists today. He had the liberty to indulge in wide-ranging digressions that at times became streams of consciousness. This freedom allowed him the scope to tackle issues that he might otherwise have avoided. In particular, Darwin was not afraid to address problems associated with his theory of evolution by natural selection. He did so often, and at length.
This book is about one of Darwin's problems. It began as a small difficulty with honeybees. At first glance, it did not seem like the sort of complication that could sink a theory that many have characterized as the most important one that biology has ever produced. But it turned into a problem that troubled biologists, fascinated naturalists, engaged popular writers and the general public, and even worked its way into political discourse for the next 145 years.
Honeybees had been introduced into Britain around a.d. 45, and by Darwin's day, some five hundred authors had written on bees and beekeeping. By the start of the eighteenthcentury, England had become the world's leader in the production of apicultural products such as honey and wax, and The Philosophical Transactions of the Royal Society of London was an important repository for articles about various aspects of bee life. What's more, the public had fallen in love with bees, particularly when it discovered some of the intriguing natural history of these insects. Bee enthusiasts described how worker bees who were fed "royal jelly" developed into queens and how the same bee egg would develop into a male if it remained unfertilized but become a female if it was fertilized with a drone's sperm.
In practice, what the scientific and public love affair with bees meant was that they could not be ignored in the Origin, and as Darwin biographer Janet Browne notes, Darwin "was specially exorcised over honey bees." If any aspect of bee life was at odds with natural selection, then Darwin understood that it had to be addressed front and center in order for his theory to be credible. One such problem was the existence of nonreproductive-that is, sterile-castes that often occur in insects such as bees, wasps, and ants. These workers are true altruists. In the first place, they do not reproduce but instead provide all sorts of resources to queens-the individuals who do reproduce. That alone would make them altruists, in the sense of incurring a personal cost that in turn benefits others. Some, but not all, sterile workers will also defend the hive tirelessly, if need be, with their own lives. This too constitutes an act of altruism, and so the sterile workers who defend the hive are, in a sense, doubly altruistic. And what's more, these bees are designed differently from others in the hive. Differences in size and shape, in fact, allow them to be particularly adept at being altruists.
Sterile social insects were clearly a hurdle for Darwin's theory of natural selection, which posited that only those traits that increased an individual's reproductive success would, over subsequent generations, increase in frequency. Sterility and kamikaze-like hive defense would seem to be precisely the sorts of traits that natural selection should operate against, and Darwin knew it.
The process of natural selection, as Darwin saw it, was simple yet extremely powerful: "Natural selection can act only by the preservation and accumulation of infinitesimally small inherited modifications, each profitable to the preserved being." For example, Darwin asked his reader to imagine the wolf that "preys on various animals, securing some by craft, some by strength, and some by fleetness." When prey for wolves are scarce, natural selection acts with brute force on wolf populations. "Under such circumstances," Darwin argued, "the swiftest and the slimmest wolves would have the best chance of surviving and so be preserved or selected.... I can see no more reason to doubt this, than that man can improve the fleetness of his greyhounds by careful and methodical selection." Wolves possessing the traits that best suit them for hunting survive longer and produce more offspring-offspring, in turn, who possess the very traits that benefited their parents in the first place. Generation after generation, "slow though the process of selection may be," noted Darwin, eventually you end up with a wolf better adapted for hunting. There is nothing remotely altruistic going on here: individual wolves do better when they possess certain traits than when they do not, and selection operates to increase the frequency of such traits.
Darwin recognized that natural selection not only operates on morphology (as in the wolf case), but on behavior as well. If behavioral traits were passed from parent to offspring, and these traits had strong, positive effects on longevity and reproductive output, selection would favor such behavioral traits over others. Darwin nicely illustrated how natural selection could operate on behavior by using the egg-laying habits of the cuckoo, a bird notorious for depositing its eggs in the nests of other species. How could such a bizarre trait evolve? What's in it for the cuckoo that such odd behavior should be favored by natural selection?
For Darwin, the potential benefits for parasitic egg-laying behavior abounded. Following his lead, imagine that at the start of this evolutionary process some cuckoos occasionally laid some of their eggs in the nest of another species. Darwin believed that parasitic egg layers might profit "by this occasional habit through being enabled to migrate earlier ... or if the young were made more vigorous by ... the mistaken instinct of another species than reared by their own mother." Migrating early and producing more "vigorous" offspring will clearly be favored by the process of natural selection. With such benefits available, if young cuckoos inherited their mother's tendencies to lay eggs in the nests of others, as Darwin thought them "apt" to do, then "the strange instinct of our cuckoo could be, and has been, generated." And again, there is no altruism in play here. As with the wolf case, if one variant of a trait-slim, sleek wolf morphology or parasitic egg-laying behavior-is superior to other variants, and if some means exists by which traits are passed from parent to offspring, then natural selection will produce a better-adapted organism.
Evolutionary biologists today recognize that offspring resemble their parents because they inherit their parents' genes. Darwin did not know about genes, nor did he need modern-day genetics for his theory to work. All he needed to realize was that somehow traits that affected reproductive success were passed from parents to offspring. Any Victorian naturalist worth his salt would have known that offspring resemble their parents, and Darwin was more than a good naturalist, he was a great naturalist.
Since Darwin, of course, Mendel's laws of genetics have become a staple of modern biology, and with the current revolution in molecular genetics, we have a deep understanding of how important genes are in shaping virtually every trait. When it comes to genes and behavior, the modern notion that genes are the fundamental unit passed from generation to generation, and hence the target of natural selection, is often referred to as the "selfish gene" approach-a term first coined by Richard Dawkins in his 1976 book, The Selfish Gene. For Dawkins, this approach does not imply that genes are selfish in any emotional or moral sense. In fact, he notes, genes are not anything but a series of tiny bits of DNA put together in a particular sequence and orientation, and somehow distinct from other such tiny bits of DNA. Yet genes can be viewed as "selfish," in that the process of natural selection favors those that can somehow or another get the most copies of themselves into the next generation. In many cases, this will simply come down to a gene's coding for a trait that increases the direct reproductive success of the individual in which it resides. But, as we shall see, this is not the only mechanism by which a gene can get more and more copies of itself into the next generation. There are more indirect, but equally powerful, ways for genes to get lots of copies of themselves passed down from one generation to the next.
Natural selection promotes genes that appear to be selfish, in the sense of favoring those that maximize the number of copies of themselves that make it to the next generation. Indeed, one of the reasons that Dawkins chose the term "selfish gene" as a metaphor was to emphasize the fact that genes which code for any trait that benefits the species as a whole, or indeed even groups of unrelated individuals, are doomed. Such genes are bound for the evolutionary trash bin because they are not maximizing their chances of being passed to the next generation. Only those genes that are "selfish" make it in the end. Wolf morphology and cuckoo behavior fit nicely into the selfish gene framework; altruism and self-sacrificial hive defense in bees do not, or at least so it appears at first glance.
In the case of Darwin's problem with the bees, he was forced to ask how his theory of natural selection could explain the existence of whole castes of insects that never reproduce and yet protect those that do, even at the cost of their own lives. In other words, what's in it for the altruists? Surely such traits should disappear, and fast, if natural selection worked the way it was supposed to. Altruistic worker bees-whom Darwin recognized as undertaking acts that were "profitable" for others in their hive-appeared to fly directly in the face of his logic.
The existence of sterile altruistic castes was an anomaly that had vexed Darwin since the early 1840s. His worries seem to have stemmed, at least in part, from a reading of Reverend William Kirby and William Spence's textbook Introduction to Entomology, in which the authors argued that the incredible behaviors of sterile castes were evidence of the divine hand of the Creator in motion. Darwin's annotations in his own copy of Kirby and Spence's book demonstrate his clear frustration with both the authors' ignorance of basic biology-for example, they implied that neuters could breed-and the whole question of sterile castes and what they meant for his own ideas.
Darwin himself had dabbled in small-scale experiments with social insects at Down House, in one case enlisting the help of his children (William, Henrietta, George, Frank, and Leonard) to better understand various aspects of bee behavior, such as their navigational skills from hive to hive. At one point he had "five or six children each close to a buzzing place," at which point Darwin would tell "the one farthest away to shout out 'here is a bee' as soon as one was buzzing around." Then, like a volunteer fire brigade passing buckets of water down a line, the children along the bee's route would continue signaling until the bees reached Darwin. Though this unconventional use of very young researchers helped Darwin understand communication in social insects, these quasi experiments did little to provide an answer to the mystery of the altruistic castes that permeate the social insects.
It is hard to overemphasize just how concerned Darwin was about the problem of sterile animals that helped others through their acts of altruism. That was simply not the way he envisioned natural selection operating, and at times, the problem of the sterile altruists would, as he himself noted, drive him "half mad." So frustrated was he, that in the Origin, Darwin summarized the whole topic of sterile castes as "one special difficulty, which at first appeared to me to be insuperable, and actually fatal to the whole theory."
Over the course of many years Darwin tinkered with a number of hypotheses that might reconcile the altruistic caste problem-a problem that centered on insects but had implications for any behavior that involved helping others at a cost to self-with his theory of natural selection. In the end, he speculated on how blood kinship might solve the problem of sterile altruistic insects. A hundred years later these ideas would be formalized through an equation that would be called "Hamilton's rule," an equation that would revolutionize the field of evolution and behavior, but the seeds of which were laid in the Origin.
In a section of the Origin entitled "Objections to the Theory of Natural Selection as Applied to Instincts: Neuter and Sterile Insects," Darwin proposed that the problem of natural selection's producing sterile individuals that often risk their lives to protect others, and appear designed to do just that, " ... disappears when it is remembered that selection may be applied to the family, as well as the individual, and may thus gain the desired end." Help your blood kin-your family-and you can make up for any costs that you yourself incur. Take the case of the altruistic bees. Even though individual bee altruists often paid a huge cost both by defending the hive and by not reproducing, this cost was made up by the benefits accrued by their family members, and hence altruistic behavior could, in principle, evolve. In addition to acting as hive guards, in his Species Book, Darwin hypothesized that selection might favor such sterile workers, as they also specialize on other tasks, such as foraging. This in turn benefits all family members by relieving them of the task of foraging, and eventually it became very clear to Darwin "how useful their production may have been." Blood kinship and interactions among relatives it turned out, was the key to solving Darwin's problems with both sterility and altruism.
Darwin seems to have realized the importance of the role of blood kinship in explaining altruism as early as 1848. In a manuscript dated June of that year, he hinted at its importance in the context of how some hives with sterile castes may "predominate" over other hives, presumably as a result of actions that sterile caste members may undertake to help their kin-in Darwin's words, selection would act on "families and not individuals." Help your relatives and you help yourself, albeit indirectly. These ideas, over the course of the next hundred years, would develop into what is today called "kin selection" theory.
The case Darwin presented amounted to this: natural selection could favor the evolution of sterile castes if individuals in such castes helped their blood kin (which they do), because doing so would help ensure the survival of those individuals that could reproduce-individuals with a hereditary makeup very similar to their own. If kin helped each other, even assuming a large cost of so doing (picture the worker honeybee's suicidal attack on nest predators) the process of natural selection could still favor such a trait, because those being helped were similar in their makeup to those doing the helping. In modern-day terms, genes can increase their frequency in the next generation by aiding the reproduction of copies of themselves that just happen to reside in other individuals-blood relatives. Again, Darwin did not know about genes per se, but he did know that blood relatives resembled one another more than strangers, and this was just enough information to speculate on the role of kinship in the evolution of altruism.
Excerpted from The Altruism Equation by Lee Alan Dugatkin Copyright © 2006 by Princeton University Press. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Chapter One: A Special Difficulty That Might Prove Fatal 1
Chapter Two: Darwin's Bulldog versus the Prince of Evolution 12
Chapter Three: The Greatest Word from Science since Darwin 37
Chapter Four: J.B.S.: The Last Man Who Might Know All There Was to Be Known 61
Chapter Five: Hamilton's Rule 86
Chapter Six: The Price of Kinship 107
Chapter Seven: Spreading the Word 115
Chapter Eight: Keepers of the Flame 123
Chapter Nine: Curator of Mathematical Models 142