Masters of the Planet: The Search for Our Human Origins

Masters of the Planet: The Search for Our Human Origins

by Ian Tattersall
     
 

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50,000 years ago – merely a blip in evolutionary time – our Homo sapiens ancestors were competing for existence with several other human species, just as their own precursors had been doing for millions of years. Yet something about our species separated it from the pack, and led to its survival while the rest became extinct. So just what was it

Overview

50,000 years ago – merely a blip in evolutionary time – our Homo sapiens ancestors were competing for existence with several other human species, just as their own precursors had been doing for millions of years. Yet something about our species separated it from the pack, and led to its survival while the rest became extinct. So just what was it that allowed Homo sapiens to become Masters of the Planet? Curator Emeritus at the American Museum of Natural History, Ian Tattersall takes us deep into the fossil record to uncover what made humans so special. Surveying a vast field from initial bipedality to language and intelligence, Tattersall argues that Homo sapiens acquired a winning combination of traits that was not the result of long term evolutionary refinement. Instead it emerged quickly, shocking their world and changing it forever.

Editorial Reviews

Publishers Weekly
Tattersall (The Fossil Trail), a noted expert on human evolution and an emeritus curator at the American Museum of Natural History in New York City, offers a concise history of how humans became humans. He explains how the sparse skeletal remains of ancient human predecessors are studied, how the shape of a molar, the tip of a pelvis, the design of the knee or the ankle all offer clues to the genealogical maps of our past. He revisits the usual suspects: the famous three-million-year-old Lucy; the unprecedented (in 1984) hominid structure of the Turkana Boy; and the 400,000-year-old Heidelberg man. Tattersall moves through the complex fossil records effortlessly and with a welcome sense of wonder. He also consistently conveys a deep knowledge of his subject. His discussion of the origin of symbolic behavior and the many theories that seek to explain early humans’ unprecedented leap in capacity, including the acquisition of language, the development of art, and the ability to deal in the abstract, is provocative and illuminating. Tattersall’s combination of erudition and a conversational style make this is an excellent primer on human evolution. Illus. (Jan.)
From the Publisher

“Quietly magnificent” —The Atlantic, runner-up for the best book of 2012

“Fantastically interesting…Tattersall has been involved in many of the past half-century's advances in understanding human evolution…Essential.” —Choice, a 2013 outstanding title

“An authoritative snapshot of the ongoing struggle to understand our evolutionary past.” —Financial Times

“A guide for the perplexed student of human origins ... Tattersall weaves a history of palaeoanthropology into the text, showing that though fossils may provide the bulk of the evidence for human origins, few of the details are set in stone.” —New Scientist

“Tattersall is no slouch in the storytelling department, but his narrative emphasizes the necessarily fragmentary nature of the fossil record and the provisional nature of what we can safely conclude from it ...[His] account highlights the major advances in paleoanthropology that have been made in the last decade or two.” —Natural History magazine

“An efficient survey of 7 million years of evolutionary development and two centuries of evolutionary thought ... In deft combinations of authority and caution, expertise and wit, Tattersall invites the lay reader to the party. Throughout, he remains grounded in the salient details culled from archaeology, anatomy, genetics, primatology, nutrition and social science.” —The Cleveland Plain Dealer

“Asuperb overview of how our species developed (a long process) and how we grew smart enough to dominate the planet ... Keeping a critical eye on the evidence and a skeptical one on theories, Tattersall confirms his status among world anthropologists by delivering a superior popular explanation of human origins.” —Kirkus Reviews starred review

“A concise history of how humans became humans ... Tattersall moves through the complex fossil records effortlessly and with a welcome sense of wonder. He also consistently conveys a deep knowledge of his subject ... Tattersall's combination of erudition and a conversational style make this is an excellent primer on human evolution.” —Publishers Weekly

“This is a book I will be recommending to anyone who wants a good overview of evolution. This book puts the new discoveries in their proper sequence and perspective. It is an excellent work.” —Jean Auel, author of The Clan of the Cave Bear, and the rest of Earth's Children books

“We all think we know the story: first we evolved to walk upright, then use tools, then agriculture, language, and us - - an inexorable linear progression from ape to human. But Ian Tattersall introduces us to several different human-like precursors, all alive at the same time, as recently as 50,000 years ago - just barely before the period we humans chauvinistically refer to as 'history'. So it's no longer straightforward: beasts like us emerged several times within the past hundred thousand years, some of them distinct species. Some were the first to think like we do: in symbols and abstractions; those were our forebears. But while they were alive, these multiple different humanoids may have known about each other; interacted; fought; lived together or apart; possibly even bred. It turns out that our lineage is anything but linear; Tattersall demolishes the versions we were once taught, and lays out the remarkable new history of our diverse origins for the first time.” —Richard Granger, author of Big Brain

“Are you ready for a 3.5 billion year stroll down the path of life's origins to the present. Ian Tattersall takes you by the hand and covers the highlights like few are capable of doing. The continuities and discontinuities reveal insights on why we humans are the masters of the planet. A must read.” —Mike Gazzaniga, author of Human: The Science Behind What Makes Your Brain Unique

“This [book] is excellent ... Among other things, and very importantly, it is a very good read.” —Colin Tudge, author of The Link: Uncovering Our Earliest Ancestor

“For almost 40 years, Ian Tattersall has been one of our leaders in the field of human evolution. Mastersof the Planet is a stunning culmination of a career in science: a brilliant and engaging account that illuminates and inspires. Read Tattersall and you will not see yourself, let alone our entire species, in the same way again.” —Neil Shubin, author of Your Inner Fish

“This is a book full of wisdom: the distillation of a lifetime's experience combined with finely honed critical faculties. Tattersall is a captivating and surefooted guide through the ranks of hominids, over several million years, in search of the origins of our uniquely symbolic mind. He ranges widely across evidence from DNA sequences and molecular forensics to skeletal morphology and ancient artifacts, never shirking the telling detail, never lacking a finely judged opinion, yet always making the science beautifully clear. The best guide to human origins that I have read.” —Nick Lane, author of Life Ascending and Oxygen

author of Human: The Science Behind What Makes Mike Gazzaniga

Are you ready for a 3.5 billion year stroll down the path of life's origins to the present. Ian Tattersall takes you by the hand and covers the highlights like few are capable of doing. The continuities and discontinuities reveal insights on why we humans are the masters of the planet. A must read.
author of The Link: Uncovering Our Earliest An Colin Tudge

This [book] is excellent ... Among other things, and very importantly, it is a very good read.
Library Journal
Tattersall (cocurator, Spitzer Hall of Human Origins, American Museum of Natural History) has authored and coauthored over 22 books on human evolution and is currently working on a multivolume project to document the major fossils in the human fossil record. He calls this book a progress report on human paleoanthropology, in which he pulls together the newest discoveries and current theories on the origins of humanity. Most of us learned that human evolution was a single line from the earliest upright apes to Homo sapiens, but Tattersall introduces readers to the wide range of species, many that lived at the same time, that are contenders for places on our ancestral tree. Even more interesting is his discussion of the factors that made us such a successful species and how these traits developed. He extrapolates from the limited physical evidence available what types of environments our precursors lived in as well as their social and mental abilities. VERDICT An excellent book for high school and college students as well as general readers.—Betty Galbraith, Washington State Univ. Lib., Pullman
Kirkus Reviews
A veteran anthropologist writes a superb overview of how our species developed (a long process) and how we grew smart enough to dominate the planet (a short process in which evolution played little part). Tattersall (Paleontology: A Brief History of Life, 2010, etc.), curator emeritus at the American Museum of Natural History, begins with early hominids, who took the first step away from apedom about five million years ago by rising to walk on two legs. In absorbing detail, he describes two centuries of often-grueling field research that turned up more species that learned to make tools and whose brains slowly grew. For three million years, our small-brained ancestors, the Australopithecus genus, spread throughout Africa before leaving the scene. From about two million years ago, bigger-brained members of genus Homo ranged across Eurasia without making a great impression. Homo sapiens, remarkably young at 200,000 years, did not seem a great improvement until about 60,000 years ago, when their brains began processing information symbolically, leading to language, art, technology and sophisticated social organization, all of which accompanied our species across the world, wiping out competing hominids. While researchers argue over why this happened, Tattersall emphasizes that evolutionary milestones, even dramatic ones like flying, do not happen when new features appear but take advantage of those already present. Feathers existed long before birds flew, and Homo sapiens' brains were always capable of great things. Keeping a critical eye on the evidence and a skeptical one on theories, Tattersall confirms his status among world anthropologists by delivering a superior popular explanation of human origins.

Product Details

ISBN-13:
9781137000385
Publisher:
St. Martin's Press
Publication date:
03/27/2012
Series:
MacSci
Sold by:
Macmillan
Format:
NOOK Book
Pages:
288
Sales rank:
318,830
File size:
3 MB

Read an Excerpt

Masters of the Planet

The Search for Our Human Origins


By Ian Tattersall

St. Martin's Press

Copyright © 2012 Ian Tattersall
All rights reserved.
ISBN: 978-1-137-00038-5



CHAPTER 1

ANCIENT ORIGINS


Among the most important influences not only on how ancient creatures evolved, but on their preservation as fossils, has been the geography and topography of the Earth itself. This has been as true for our group as for any other, so it's worth giving a bit of background here. During the Age of Mammals that followed the demise of the dinosaurs some 65 million years ago, much of the African continent was a flattish highland plateau. This slab of the Earth's crust lay over the roiling molten rocks of the Earth's interior like a great thick blanket, trapping the heat below. Heat must rise, and eventually ascending hot rock began to swell the rigid surface above.

Thus began the formation of the great African Rift, the "spine of Africa," that formed as a series of more or less independent but ultimately conjoined areas of uplift known as "domes." These blistered and split apart the continent's surface along a line that started in Syria, proceeded down the Red Sea, then south from Ethiopia through East Africa to Mozambique. The Rift's major feature, the Great East African Rift Valley, formed as a complex chain of sheer-sided depressions when the swelling below cracked the inflexible rock at the surface. As the continent continued to rise with the injection of more hot rock from below, erosion by water and wind began to deposit sediments in the valley floors — sediments that contain an amazingly rich assortment of fossils. As a category, fossils technically include any direct evidence of past life, but the overwhelming majority of them consist of the bones and teeth of dead animals that were luckily — for paleontologists — covered and protected by marine or lake or river sediments before they could be obliterated by scavengers and the elements. And, as fate would have it, the sedimentary rocks of the Rift Valley include the most remarkable fossil record we have, from anywhere in the world, of the long history of mankind and its early relatives.

In eastern Africa, Rift sediments began to be deposited in the Ethiopian Dome about 29 million years ago, and similar deposits mark the initiation of the Kenya Dome only a few million years later, at about 22 million years. This occurred during the period known to geologists as the Miocene epoch, and it happens to have been an exceptionally interesting time in primate evolution, as the fossil record shows. It was what you might call "the golden age of the apes," and it set the stage for the evolution of the human family, which appeared toward its end.

Today's Great Apes — the chimpanzees, bonobos, gorillas, and orangutans — constitute a mere handful of forest species now restricted to tiny areas of Africa and a couple of southeast Asian islands. But the Miocene was the apes' heyday, and over its 18-million-year extent, scientists have named more than 20 genera of extinct apes from sites scattered all around the Old World, though mostly in East Africa. The earliest of these ancient apes are known as "proconsuloids." They scampered along the tops of large branches in the humid forests of the eastern African early Miocene in search of fruit, some 23 to 16 million years ago. Like today's apes, they already lacked tails; but in many ways they were more monkeylike, with less flexible forelimbs than those their descendants eventually acquired.

Around 16 million years ago, African climates seem to have become drier and more seasonal, changing the character of the forests. True monkeys began to flourish in the new habitat, and the proconsuloids themselves yielded to "hominoid" apes that more closely resembled their modern successors. Most notably, the apes of the later Miocene developed mobile arms that they could freely rotate at the shoulder joint, allowing efficient suspension of the body beneath tree branches and imparting all-around greater agility. These early hominoids also typically had molar teeth with thick enamel that were set in robust jaws, allowing them to tackle a broad range of seasonally available forest foods as they began spreading beyond the Afro-Arabian region into Eurasia.

In both Eurasia and Africa, paleontologists have found the remains of several different hominoid genera that date back between about 13 and 9 million years ago. These probably represent the group that gave rise to the first members of our own "hominid" family (or "hominin" subfamily; for most purposes the distinction is merely notional). Most of the genera concerned are known principally from teeth and bits of jaw and cranium; but one of them, the 13-million-year-old Pierolapithecus, is well known from a fairly complete skeleton discovered not long ago in Spain. Pierolapithecus was clearly a tree climber, but it also showed a host of bony characteristics that suggest it habitually held its body upright. Such a posture — in the trees, at least — may actually have been typical for many hominoids of the time (as it is for orangutans today). However, the skull and teeth of Pierolapithecus are different from those of any of the putative early hominids that we'll read about in a moment.


WILL THE EARLIEST HOMINID PLEASE STAND UP?

The earliest representatives of our own group lived at the end of the Miocene and at the beginning of the following Pliocene epoch, between about six and 4.5 million years ago. And they appear just as the arrival of many new open-country mammal genera in the fossil record signals another major climatic change. Oceanic cooling affected rainfall and temperatures on continents worldwide, giving rise in tropical regions to an exaggerated form of seasonality often known as the "monsoon cycle." In Europe this cooling led to the widespread development of temperate grasslands, while in Africa it inaugurated a trend toward the breakup of forest masses and the formation of woodlands into which grasslands intruded locally. This episode of climatic deterioration furnished the larger ecological stage on which the earliest known hominids made their debut.

Before we look at the varied cast of contenders for the title of "most ancient hominid," perhaps we should pause for a moment to consider just what an early hominid should look like. How would we recognize the first hominid, the earliest member of the group to which we belong to the exclusion of the apes, if we had it? The question seems straightforward, but the issue has proven to be contentious, especially since members of related lineages — such as our own and that of the chimpanzees — should logically become more similar to each other, and thus harder to distinguish, as they converge back in time toward their common ancestor. But while the characteristics that define modern groups should even in principle lose definition back in the mists of the past, attempts to recognize very early hominids have paradoxically been dominated by the search for the early occurrence of those features that mark out their descendants today.

When the Dutch physician Eugene Dubois discovered the first truly ancient human fossil in Java in 1891, he called his new find Pithecanthropus erectus ("upright ape-man"). His choice of species name emphasized the importance he attached to the erect stature of this hominid (indicated by the structure of its thighbone) in determining its human (or at least close-to-human) status. But soon thereafter the emphasis changed, at least temporarily. Modern people are perhaps most remarkable for their large brains; and in the early years of the twentieth century, brain size expansion replaced uprightness as the key criterion for any fossil seriously considered for inclusion in the hominid family. Indeed, its big human braincase (which was matched with an ape jawbone) was the basis for recognizing the famously fraudulent English Piltdown "fossil" as a human ancestor in 1912. The fraud was only officially uncovered some 40 years later, although many scientists were suspicious of it from the start; and as time passed the Piltdown specimens became increasingly ignored, which had the effect of bringing the big-brain criterion into disfavor. In its place came a behavioral yardstick rather than an anatomical one: manual dexterity and the manufacture of stone tools became the key to human status, as the notion of "Man the Toolmaker" took hold.

But this too had its difficulties. Eventually and inevitably, attention refocused on anatomy, and various potentially diagnostic morphological features of hominids were touted. Teeth, which are coated with the toughest biological material and thus preserve particularly well in the fossil record, received particular attention. One dental characteristic that many noticed among potential early hominid fossils was thick molar enamel — although, as we have seen, this indicator of a tough diet is also found widely among Miocene apes. Another hominid dental feature that has perennially attracted attention is the reduction in size of the canine teeth. This occurs in conjunction with the loss of honing of the large upper canine against the front premolar of the lower jaw with which it occludes. Large-bodied male apes typically have fearsome upper canine teeth with razor-sharp back edges — although in small females these teeth can be dainty. But again, a tendency toward canine reduction is not unique to hominids. It is also found in various Miocene apes, most famously the bizarre late-Miocene Oreopithecus, an insular form that additionally showed a distinct tendency toward postural uprightness. What is more, the remarkable Oreopithecus was recently reported to have had "precision-grip capability" — something else that was once thought unique to tool-making hominids.

Part of the problem of spotting features that are unique to hominids stems from the nature of evolutionary diversification. As we look farther back into hominid history, every feature indicative of modern hominids is likely to become less distinctive — and more reminiscent of its counterparts in members of related lineages. Given this reality, it is hardly realistic to expect that we'll ever find an anatomical "silver bullet" that will by itself tell us infallibly if an ancient fossil is a hominid or not. Every effort to do this has foundered on one technicality or another. Take, for example, the early-twentieth-century attempt of the English anatomist Sir Arthur Keith to set a "cerebral Rubicon" of 750 cubic centimeters (cc) minimum brain volume for membership in the genus Homo. Any smaller than this, Keith said, and you didn't belong to the club. This was certainly a convenient and easily measurable criterion; and, at a time when very few hominid fossils were known, perhaps it was even a workable one. But predictably, as the hominid fossil sample increased, problems arose. Brain size is notably variable within populations (modern human brains range in size from about 1,000 to 2,000 cc, with no indication that people with larger brains are necessarily smarter), so that even in principle this standard might have admitted an ancient hominid to our genus while excluding his or her parents or offspring. Accumulating fossil finds predictably forced later authors to lower Keith's figure several times, until it became obvious that the entire "Rubicon" idea was misguided.

Similar objections apply to any touchstone of this kind for membership in the genus Homo or the family Hominidae. But the temptation to see matters from the "key criterion" perspective is nevertheless always there. Indeed, in recent years paleoanthropologists have come full circle back to Dubois' view, so that the most notable common factor uniting all currently touted "earliest hominids" is the claim that each had walked bipedally on the ground. This seemingly straightforward standard for membership in our family is particularly attractive given that in the latest Miocene the eastern African forests were beginning to yield to patches of more open territory. This would have obliged at least some ape populations to spend more time on the ground (though extinction was, as always, the easier option for steadfastly arboreal types). Still, if this environmental change forced one ape lineage to stand upright, why not others? Several likely did; but only one of them can have been the hominid progenitor.

A further confounding factor is that all of the known "very early hominid" fossils have been found in contexts indicating thickly wooded habitats, or at least mixed ones. The earliest hominids were thus not obliged to walk upright on the ground by the disappearance of their ancestral habitat. We humans have rather reductionist minds, and are beguiled by clear, straightforward explanations. But where murky Mother Nature is concerned, beware of excessively simple stories.


THE CAST OF CHARACTERS

Until close to the turn of this century, the known hominid fossil record extended back in time to only about three to four million years ago. But a remarkable series of finds has since turned up a variety of contenders for the mantle of "earliest" hominid that are significantly older than this. The oldest of them come from around the time that DNA studies suggest our ancestors parted company with our closest ape relatives, believed to be the chimpanzees and bonobos.


"Toumaï" andOrrorin

The most ancient of the "earliest hominids" on offer today is the close-to-seven-million-year-old species Sahelanthropus tchadensis, discovered in 2001 in the central-western African country of Chad (well to the west of the Rift Valley). What has so far been published of this form consists of a badly crushed cranium (informally dubbed "Toumaï" — "hope of life" in the local language) and some partial mandibles. These fossils caused a stir when discovered, because nobody had anticipated an ancestral hominid like this. What was particularly strange about Toumaï was that it combined a small (hence rather apelike) braincase with a large, flattish face that was distinctly unlike the more protruding snouts of younger fossil hominids (or apes, for that matter). Two things caused its describers to classify this form as a hominid: first, the teeth. The molars had moderately thick enamel, the canines were reduced, and there was no lower premolar honing mechanism. So far, so good; but as we've seen, both thick enamel and the reduced canine-premolar complex can be matched outside Hominidae. So the key finding was in the base of the crushed cranium, where the foramen magnum, the large hole through which the spinal cord exits the cranium, appeared to be shifted underneath the skull to face largely downward. This is significant in that you would expect to find this setup in an upright biped like us: a skull balanced atop an erect spine. In a quadrupedal chimpanzee, the skull hangs on the front of a horizontal spine, so the foramen magnum has to be at the rear of the skull, facing backward. Unfortunately, though, the skull of Sahelanthropus was badly crushed, so the crucial claim about its foramen magnum was inevitably disputed.

In response, researchers took CT-scans of the crushed skull in a medical scanning machine, and produced a computerized virtual reconstruction that eliminated the distortions. Now, no matter how high-tech the procedure is, there's always an element of human judgment involved in making any reconstruction. But the resulting model of the pristine Sahelanthropus skull gave its creators substantial grounds for viewing Toumaï as plausibly — if not definitively — the skull of a biped. There are still some skeptics; but although the bipedality question will never be finally settled until key parts of the body skeleton of Sahelanthropus are announced, the reconstruction does appear to give this form the benefit of the doubt.

If Toumaï was a hominid — or even if he wasn't — what can we say about his way of life? Fossils found in the same deposits suggest that Sahelanthropus lived in an environment that was well watered, with forest in the close vicinity. This doesn't tell us much directly, but it does say something about the kind of resources that were available to this presumed ancestor. Put this information together with its posture, its habitat, and the general form of its teeth, and it seems reasonable to suggest that Sahelanthropus was at least a part-time biped that subsisted on a fairly generalized plant-based diet that would have included fruit, leaves, nuts, seeds, and roots, and probably extended to insects and small vertebrates such as lizards. For the moment it's probably unwise to say too much beyond that, though we'll speculate a bit about such things as the nature of early hominid sociality in a little while.


(Continues...)

Excerpted from Masters of the Planet by Ian Tattersall. Copyright © 2012 Ian Tattersall. Excerpted by permission of St. Martin's Press.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Meet the Author

Ian Tattersall, PhD is a curator in the Division of Anthropology of the American Museum of Natural History in New York City, where he co-curates the Spitzer Hall of Human Origins. He is the acknowledged leader of the human fossil record, and has won several awards, including the Institute of Human Origins Lifetime Achievement Award. Tattersall has appeared on Charlie Roseand NPR's Science Friday and has written for Scientific American and Archaeology. He's been widely cited by the media, including The New York Times, BBC, MSNBC, and National Geographic. Tattersall is the author of Becoming Human, among others. He lives in New York City.


Ian Tattersall, PhD is a curator in the Division of Anthropology of the American Museum of Natural History in New York City, where he co-curates the Spitzer Hall of Human Origins. He is the acknowledged leader of the human fossil record, and has won several awards, including the Institute of Human Origins Lifetime Achievement Award. Tattersall has appeared on Charlie Rose and NPR's Science Friday and has written for Scientific American and Archaeology. He's been widely cited by the media, including The New York Times, BBC, MSNBC, and National Geographic. Tattersall is the author of Becoming Human, among others. He lives in New York City.

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