The Accidental Species: Misunderstandings of Human Evolution

The Accidental Species: Misunderstandings of Human Evolution

by Henry Gee

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Overview

The idea of a missing link between humanity and our animal ancestors predates evolution and popular science and actually has religious roots in the deist concept of the Great Chain of Being. Yet, the metaphor has lodged itself in the contemporary imagination, and new fossil discoveries are often hailed in headlines as revealing the elusive transitional step, the moment when we stopped being “animal” and started being “human.” In The Accidental Species, Henry Gee, longtime paleontology editor at Nature, takes aim at this misleading notion, arguing that it reflects a profound misunderstanding of how evolution works and, when applied to the evolution of our own species, supports mistaken ideas about our own place in the universe.   Gee presents a robust and stark challenge to our tendency to see ourselves as the acme of creation. Far from being a quirk of religious fundamentalism, human exceptionalism, Gee argues, is an error that also infects scientific thought. Touring the many features of human beings that have recurrently been used to distinguish us from the rest of the animal world, Gee shows that our evolutionary outcome is one possibility among many, one that owes more to chance than to an organized progression to supremacy. He starts with bipedality, which he shows could have arisen entirely by accident, as a by-product of sexual selection, moves on to technology, large brain size, intelligence, language, and, finally, sentience. He reveals each of these attributes to be alive and well throughout the animal world—they are not, indeed, unique to our species.

The Accidental Species combines Gee’s firsthand experience on the editorial side of many incredible paleontological findings with healthy skepticism and humor to create a book that aims to overturn popular thinking on human evolution—the key is not what’s missing, but how we’re linked.

Product Details

ISBN-13: 9780226044989
Publisher: University of Chicago Press
Publication date: 10/15/2013
Sold by: Barnes & Noble
Format: NOOK Book
Pages: 232
File size: 2 MB

About the Author

Henry Gee is a senior editor at Nature and the author of such books as Jacob’s Ladder, In Search of Deep Time, The Science of Middle-earth, and A Field Guide to Dinosaurs, the last with Luis V. Rey. He lives in Cromer, Norfolk, England, with his family and numerous pets.

Read an Excerpt

The Accidental Species

MISUNDERSTANDINGS OF HUMAN EVOLUTION


By Henry Gee

THE UNIVERSITY OF CHICAGO PRESS

Copyright © 2013 Henry Gee
All rights reserved.
ISBN: 978-0-226-28488-0



CHAPTER 1

An Unexpected Party


Many years ago I was a paleontologist. I studied fossil bones. Each bone is mute testimony to the existence of a life, in the past: of an animal the likes of which might have vanished from the earth. I gave up being a full-time bone-botherer when I found myself on the staff of Nature, the leading international journal of science.

I was a junior news reporter on a three-month contract. My first assignment, at 9:30 a.m. on Monday, 11 December 1987, was to write a brief piece on new radiological protection guidelines, of which I knew nothing whatsoever. By noon, however, I was to deliver a well-turned, terse, and, most importantly, authoritative story that could stand the scrutiny of Nature's discerning readers.

It wasn't long before I accreted the job of writing Nature's weekly press release—a document that goes out to journalists around the world, keen to learn the latest stories from the frontiers of science. Given that, like me, many journalists would be unlikely to understand all the technical details in each paper, my task was to write a document that would summarize the essence of each in language that would be generally comprehensible. It was an enjoyable and mind-stretching task. On any given day I might be writing about anything in science, from high-energy physics to the molecular biology of HIV-1.

I also got some practice at writing catchy headlines.

My favorite press-release headline concerned a story about mice apt to lose their balance and fall over. The researchers found a genetic mutation responsible for this defect. The research was important because it allowed an insight into a distressing hereditary disease called Usher's syndrome, which is responsible for most cases of deaf-blindness in humans, and which can also include loss of balance. To paraphrase what the humorist Tom Lehrer noted about himself, my muse is sometimes unconstrained by such considerations as taste: so my headline was (hey, you're way ahead of me here)


THE FALL OF THE MOUSE OF USHER

A perk of being the press-release writer was to sit on the weekly meeting of editors trying to decide what would be on Nature's cover two weeks hence. It was here that I first began to appreciate that editors at Nature are among the first to hear about new insights into the unknown. In 1994, two marine biologists sent us an amazing photo captured by the Alvin submersible at a depth of more than 2,500 meters. The picture was dramatic, contrasty, and gothic. Picked out in harsh spotlights, exposé-style, it showed two octopi, each of a diff erent species unknown to science, but both male, and having sex. A colleague suggested that this would make an arresting cover picture—another, however, demurred, on the grounds that it was "disgusting." At this point I spoke up—I can still hear myself saying the words—"we can always put black rectangles over their eyes." My mind raced ahead, composing an arresting press-release entry that would be headed with the line


BESTIAL SODOMY IN THE ABYSS

In this case, taste intervened and I used something less lurid. The picture didn't make the cover, either.

I mention all this to excuse some of what follows—if I am critical of journalists and news editors, my criticism comes from experience. I know what it is like to work on a story to a tight deadline, and from a position of relative ignorance. I can also appreciate that the term "missing link," which seems to encapsulate so much in so little space, exerts an almost irresistible allure, even though it represents a completely misleading view of what evolution is, how it works, and the place that human beings occupy in nature.

In the course of time, I migrated from the news department to the "back half," the team of editors who have the immense privilege of selecting which research papers from the stream of submissions will be published in the journal. One of the pleasures of the job is receiving the first news of important, potentially world-changing discoveries.

An account of perhaps the single most remarkable discovery I've seen in my career as an editor was submitted to Nature on 3 March 2004. The discovery was of something quite unexpected, opening up unsuspected vistas on things we didn't know we didn't know, and challenging conventional assumptions about the inevitable ascent of humankind to a preordained state as the apotheosis and zenith of all creation. After several revisions, and much discussion among my colleagues and the panel of scientists we'd assembled to advise us on the report of the discovery, the news was published in Nature on 28 October 2004.

This communiqué from beyond the realms of the known came from an international team of archaeologists working in a cave called Liang Bua, on the remote island of Flores, in Indonesia. If you want to find Flores on a map, look up the island of Java, and work your way eastward, past Bali and Lombok, and there it is. Flores is part of a long chain of islands that ends up at the island of Timor, well on the way to Australia, New Guinea, and the Pacific Ocean.

One of the more intriguing questions in archaeology is when Australia was first settled by modern humans, the ancestors of today's aboriginal peoples. There is much debate about this issue. Clearly, one way of illuminating the problem is to search for early modern humans living in what is now Indonesia, which can be thought of as a series of stepping-stones between mainland Asia and Australia. That's where Flores comes in. Archaeologists are interested in the caves of Flores and other islands such as Timor because of their potential to yield remains of Homo sapiens, modern people caught in the act of heading toward that distant island continent later associated with cold lager, "Waltzing Matilda," and The Adventures of Priscilla, Queen of the Desert. This is what drew an international team of archaeologists to Flores, and in particular to Liang Bua, known as an archaeological site for decades.

Flores, though, is an island of mysteries—for it has been inhabited for at least a million years, and not by Homo sapiens. Stone tools have been discovered in several places on the island, and their makers are usually thought to have been Homo erectus, an earlier hominin, whose remains are well known from Java, China, and other parts of the world. The bones of these early inhabitants of Flores have not been found, their presence betrayed only by the distinctive stone tools they left behind.

But whoever these early inhabitants were, their very presence is a problem. In the depths of the ice ages, when much of the earth's water was locked up in ice caps and glaciers, the sea receded so far that many of the islands of Indonesia were connected by land bridges—they could be colonized by anything able to walk there. Not so Flores: this remained separate, cut off from mainland Asia by a deep channel. Homo erectus—if that's who it was—must have made the crossing from the nearest island by boat or raft, or, like other animals, washed up there by accident. Once they made landfall on Flores, there they stayed—cut off from the rest of the world for a very long time.

Isolation on islands does strange things to castaways, making them look very different from their cousins on the mainland. So it was with Flores, home to a species of elephant shrunken to the size of a pony, rats grown to the size of terriers, and gigantic monitor lizards that made modern Komodo dragons look kittenish by comparison.

Such peculiar faunas are typical of islands cut off from the mainland where, for reasons still unclear, small animals evolve to become larger, and large animals evolve to become smaller. Miniature elephants, in particular, were rather common in the ice ages. Practically every isolated island had its own species. The one on Malta lived eye-to-eye with a gigantic species of swan called Cygnus falconeri, with a wingspan of around three meters. Micromammoths evolved on Wrangel Island in the Russian Arctic, where they outlived their larger mainland cousins by thousands of years.

The fate of island faunas was an important consideration for Charles Darwin, who marveled at the creatures of the Galápagos Islands in the Pacific Ocean, when HMS Beagle visited in 1835. Darwin noted that each island had its own species of giant tortoise, as well as its own finches—different from one another yet plainly similar to finches from the mainland of South America. Had some stray finches, once marooned on the Galápagos, evolved in their own way?

The scene is set, then, for Flores, where, at Liang Bua, archaeologists surrounded by the bizarre sought for something so seemingly prosaic as signs of modern humans.

What they found instead was a skeleton, not of a modern human or anything like one, but a hominin shrunken to no more than a meter in height, with a tiny skull that would have contained a brain no larger than that of a chimpanzee.

In some ways the skull looked disarmingly humanlike. It was round and smooth, just like a human skull, and with no sign of an apelike snout. In other ways it was a throwback. The jaw had no chin—the presence of a chin is a hallmark of modern humans, Homo sapiens. The arms, legs, and feet of the creature were most odd, looking less like those of modern humans than those of "Lucy" (Australopithecus afarensis), a hominin that lived in Africa more than 3 million years ago. The big surprise, though, was its geological age. Despite its very ancient-looking appearance, the skeleton was dated to around 18,000 years ago. In terms of human evolution, this is an eyeblink, hardly rating as the day before yesterday. By that time, fully modern humans, having evolved in Africa almost 200,000 years ago, had spread throughout much of the Old World. They had long been resident in Indonesia, and indeed, Australia.

So what was this peculiar imp of a creature doing on Flores, seemingly so out of tune with its times?

Despite the tiny brain, the creature seemed to have made tools. Pinning tools on a toolmaker is very hard (we weren't there to see them do it), but these tools looked very like those known to have been made on Flores hundreds of thousands of years earlier, presumably by Homo erectus. The only difference was that they were smaller, as if fitted to tiny hands. Had the archaeologists discovered a hitherto unknown species of hominin, dwarfed by long isolation alongside the miniature elephants?

Further work at Liang Bua showed that the first skull and skeleton were no flukes. The skeleton was soon joined by a collection of more fragmentary remains, though no more skulls. All the remains could be attributed to the same species of tiny hominin, and showed its presence at Liang Bua, off and on, from as long ago as 95,000 years ago (well before Homo sapiens arrived in the area, as far as we know) to as recently as 12,000 years ago.

After that—catastrophe. A layer of ash found in the upper sediments at Liang Bua indicate that many of the inhabitants of Flores were destroyed in a volcanic eruption around 12,000 years ago. The calamity swept away the fairy-tale fauna of giant lizards, tiny elephants, and tiny people (though the giant rats are still there, to this day). More recent sediments, laid down after the eruption, betray the presence of modern humans, their tools, and their domestic animals.

The account that reached my desk at Nature made it plain that the discoverers were as honestly puzzled by their discovery as anyone else would have been, in this coal-face confrontation with the absolutely unknown and unexpected—a new species of hominin that lived until almost historical times, but with a weird, antique anatomy and a very, very small brain indeed.

To emphasize the strangeness of the creature, the discoverers gave it a scientific name that was noncommittal, yet set it apart from anything discovered hitherto. They called it Sundanthropus florianus—the Man from Flores, in the Sunda Islands. However, the panel of experts I called on to comment on the draft paper, and to make suggestions for its improvement, pointed out how relatively modern the skull looked—how much it looked like our own genus, Homo. One commentator also noted that "florianus" didn't actually mean "from Flores" so much as "flowery anus." Clearly, some revision was required.

When the revised paper was published in October, the creature had become Homo floresiensis—Flores Man. The skeleton with its skull was catalogued as LB-1, but the media were quick to catch on to a suggestion of one of the discoverers that it should be known as the "Hobbit," after the diminutive hole-dwellers of J. R. R. Tolkien's fiction—though we in the Nature office sometimes referred to her as "Flo" (the skeleton having been described as that of a female).

The paper—and the several commentaries that appeared in its wake—saw the Hobbit as a member of a race of humanlike creatures that had evolved in isolation, on Flores itself or nearby, perhaps descendants of the full-sized toolmakers known to have been on Flores for as long as a million years. If isolation on islands could do strange things to creatures as varied as birds and elephants, lizards and tortoises, there seemed no reason in principle why hominins should be exempt. The Hobbit could easily be seen as a relative of Homo erectus, known from remains on mainland Asia to be almost as tall as a modern human—but dwarfed as a result of isolation, alongside the elephants whose island it shared.

And then the fun started.

Hardly had the ink dried on the first account of the Hobbit when the backlash began. Critics were exercised by two particular aspects of the discovery.

First, that such an archaic-looking creature had existed so recently, in a region already long inhabited by modern humans.

Second, that a creature with such an incredibly tiny brain could have made tools. The brain was so tiny, even in proportion to the tiny body, that the Hobbit must—the critics reasoned—have been suffering from a physical or genetic abnormality.

Although criticism of the find came in various shades, critics were united, more or less, in proposing an alternative scenario for the existence of the Hobbit. Rather than it being a distinct species, a relic of an older world preserved out of time, it was a form of modern human suffering from microcephaly, a congenital disorder that produces midgets with abnormally small heads.

The first objection can be seen as a symptom of human exceptionalism, the erroneous yet deeply ingrained tendency that I seek to explode in this book. That is, the tendency to see ourselves as the inevitable culmination of a progressive trend of advancement in evolution. The discovery of such a primitive-looking creature living on the same planet at the same time as Homo sapiens challenges that view. It is a perhaps unfortunate fact that the only hominin that still exists on Earth is our own. This fact rather reinforces the idea that various species of hominin—the "missing links"—each more humanlike than the one before, succeeded one another with the planned inevitability of runners in a relay race, and that it is not somehow possible for several species of hominin to coexist on the same planet.

It was not always so. As recently as 50,000 years ago, there were at least four different kinds of hominin on Earth—Homo sapiens in Africa, Neanderthals (Homo neanderthalensis) in Europe and western Asia, and Homo erectus in southeastern Asia, to which must now be added the obscure "Denisovans" from eastern Asia. The addition of a fifth—Homo floresiensis—would, in such circumstances, hardly be a surprise: neither should it be a surprise were yet more distinct forms of human to be discovered. Indeed, the only period in which only one species of hominin walks the earth is right now. Modern times are the exception, not the norm.

That different hominins might live together in the same region should, likewise, not be a surprise. It is known that various kinds of early Homo coexisted with australopiths in east Africa between 2 and 3 million years ago, and that humans and Neanderthals coexisted in Europe for at least 10,000 years (between around 41,000 and 27,000 years ago). The survival of Neanderthal genes in the modern human population shows that the two species occasionally interbred. There can, therefore, be no objection to Homo floresiensis as a distinct species, simply on the basis that modern humans were around at the same time; nor on the basis that Homo floresiensis looks too primitive to have survived until modern times. As anachronisms go (what people like to call "living fossils"), the Hobbit is hardly a world-beater. Go tell it to the tuatara of New Zealand, the last relic of a lineage of reptiles distinct from a time before dinosaurs evolved, and hardly changed in its external appearance for 250 million years.
(Continues...)


Excerpted from The Accidental Species by Henry Gee. Copyright © 2013 Henry Gee. Excerpted by permission of THE UNIVERSITY OF CHICAGO PRESS.
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Table of Contents

Preface            No More Missing Links

One                  An Unexpected Party
Two                  All about Evolution   
Three               Losing It                     
Four                 The Beowulf Effect    
Five                  Shadows of the Past 
Six                    The Human Error     
Seven              The Way We Walk    
Eight                The Dog and the Atlatl                             
Nine                 A Cleverness of Crows                             
Ten                   The Things We Say   
Eleven             The Way We Think   

Afterword        The Tangled Bank

Notes
Index

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