Chip Walter - Last Ape Standing The Seven-Million-Year Story of How and Why We Survived

Thumbs, Toes, and Tears: And Other Traits That Make Us Human

Im Working on That, written with William Shatner

Space Age

Copyright 2013 by William J. (Chip) Walter Jr.

First published in the United States of America in 2013
by Walker Books, an imprint of Bloomsbury Publishing, Inc.
This electronic edition published in January 2013
www.bloomsbury.com

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You may not copy, distribute, transmit, reproduce or otherwise make available this publication (or any part of it) in any form, or by any means (including without limitation electronic, digital, optical, mechanical, photocopying, printing, recording or otherwise), without the prior written permission of the publisher. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages.

Black and white image credits. Images 1, 2, 3, 7, 10, 11, and insets within 5, 6, and 12: Frank Harris. Image 4 inset of Paranthropus aethiopicus: Sergio Prez. Image 9: based on an image provided by the National Institute of Health, 2010. Image 8: based on a drawing by T. L. Lentz, originally published in Primitive Nervous Systems (New Haven: Yale University Press, 1968).

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eISBN: 978-0-8027-7891-8 (e-book)

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For Cyn. My compass and my Gibraltar.

Despite its academic-sounding name, a good deal of brawling often goes on within the field of paleoanthropology. That it explores the deep past and counts on bits of ossified bone grudgingly revealed or scraped out of the earth doesnt help the inexactness of the science, or the disagreements it generates. Although all researchers in the field work hard to bring the objectivity of the scientific method to their work, its nature involves a lot of guesswork. So while one scientist or group of scientists may think that the unearthed fossils of a particular creature demand that it be classified as a new species, others might feel just as strongly that it is simply a new example of a species that has already been discovered. Some scientists find good reason to have created the classification Homo antecessor, for example. Others, just as reputable, and just as thorough in their thinking, argue no such species ever existed.

No one really knows. The evidence is too sparse and too random. We are making up these names as a convenient way of organizing the chaos of discovery over the past 180 years. Its not as though the creatures themselves went by the nomenclatures we have made up. Nor can we comprehend what we dont know. We can never say if we have discovered the fragmented evidence of 80 percent of our direct ancestors and cousin human species, or 1 percent.

Too often, being human, we may give the impression we understand more than we do, or that we have just about figured it all out. We havent, as you will see. One of the reasons this book is relevant is because the human family tree, or more precisely, our very limited view of it, has changed so much in just the past five years.

Advances in genetics, innovations in radiocarbon dating, together with plain old scientific creativity and elbow grease have greatly improved our guesswork and helped flesh out the discoveries we have made. There would be no hope, for example, of having even the remotest idea that a wisdom tooth and the end of a pinkie finger found in a Siberian cave three years ago belonged to an entirely new species of human (scientists call them Denisovans) with whom we and Neanderthals may share a common ancestor. This paltry evidence even revealed we mated with them! Nor would we have learned that billions of humans (including, very possibly, you) have Neanderthal mlood running in their veins. But we now know these astonishing things are true, even as they have turned assumptions once taken as gospel entirely on their heads.

Still, despite these advances and the exciting discoveries they have made possible, the illumination of our past is a little like trying to find a set of car keys in the Sahara with a flashlight.

I bring this up now to clarify a point: we dont know exactly how many other human species have evolved over the past 7 million years27 or 2700. We likely never will. But I have tried to arrive at an arguable and acceptable number that makes the larger point that, despite the disagreements that take place within the field, the story of how we came to be is a good deal more intriguing and complicated than we thought even a few years ago. And that makes the story even better.

Over the past 180 years we have so far managed to stumble across, unearth, and otherwise bring to light evidence that twenty-seven separate human (hominin, to use the up-to-date scientific term)

Of all the varieties of humans who have come and struggled and wandered and evolved, why are we the only one still standing? Couldnt more than one version have survived and coexisted with us in a world as big as ours? Lions and tigers, panthers and mountain lions, coexist. Gorillas, orangutans, bonobos, and chimpanzees do as well (if barely). Two kinds of elephants and multiple versions of dolphins, finches, sharks, bears, and beetles inhabit the planet. Yet only one kind of human. Why?

Most of us believe that we alone survived because we never had any company in the first place. According to this thinking, we evolved serially, from a single procession of gifted ancestors, each replacing the previous model once evolution had gotten around to getting it right. And so we moved step by step (Aristotle called this the Great Chain of Being), improving from the primal and incompetent to the modern and perfectly honed. Given that view, it would be impossible for us to have any contemporaries. Who else could have existed, except our direct, and extinguished, antecedents? And where else could it all lead, except to us, the final, perfect result?

This turns out to be entirely wrong. Of the twenty-seven human species that have so far been discovered (and we are likely yet to discover far more), a considerable number of them lived side by side. They competed, sometimes they may have mated, more than once one variety likely did others in either by murdering them outright or simply outcompeting them for limited resources. We are still scrounging and scraping for the answers, but learning more all the time.

If we hope to place our arrival on the scene in any sort of perspective, its a good idea to remember that every species on Earth, and every species that has ever lived on Earth (by some estimates thirty billion of them), enjoyed a long and checkered past. Each came from somewhere quite different from where it ended up, usually by a circuitous, and startling, route. Its difficult to imagine, for example, that the blue whales that now swim the worlds oceans, great leviathan submarines that they are, were once furry, hoofed animals that roamed the plains south of the Himalayas fifty-three million years ago. Or that chickens and ostriches are the improbable descendants of dinosaurs. Or that horses were once small-brained little mammals not much taller than your average cat with a long tail to match. And the Pekinese lapdogs that grace the couches of so many homes around the world can trace their beginnings to the lithe and lethal gray wolves of northern Eurasia.