The Accidental Species: Misunderstandings of Human Evolution (2 page)

As Sam Goldwyn once memorably observed, we’ve passed a lot of water since then. I followed
Deep Time
with a variety of books, from serious pop-science (
Jacob’s Ladder
) to fannish criticism (
The Science of Middle-earth
) to a coffee-table book (
A Field Guide to Dinosaurs
, illustrated by the incomparable Luis V. Rey) and even fiction (
By the Sea
and
The Sigil
)—and yet, despite their variety, all seem to draw from the same inspirational spring. That is, that science begins and ends with an appreciation of the unknown, of the vastness of our ignorance, and that this demands not arrogance but humility before the evidence. This is where, I think, the brave souls attempting to stem the creeping tide of willful (often religiously motivated) ignorance have failed. Rather than trumpeting loudly the virtues of Science, Truth, and—yes—“Facts” over Pseudoscience and Superstition, they should admit the obvious.

That is, science is not about Truth, but Doubt; not Knowledge, but Ignorance; not Certainty, but Uncertainty. Never in the field of human inquiry have so many known so much about so little. Only creationists, who are vouchsafed the answers at the back of the book (or, in this context, at the front of The Book), can afford the swaddling comfort and deceptive luxury of Truth, of Knowledge, of Facts that can be Known—because they “know” the answers already, having accepted them without question from a higher authority, as a child from a parent.

Scientists, even those who don’t know their scripture,
⁶
who have grown up, so that they feel capable of looking for their own answers rather than having them handed down to them from above, should be able to convey the wonder—the awe, terror, and insignificance—engendered by confrontation with the unknown. That, really, is what all my books have been about, and this one—I hope—represents a distillation of my entire worldview.

Once upon a time we thought the earth was the center of the universe, but were shocked to find that this was not the case. We thought that Man was the pinnacle of Creation, but despite Darwin, many still cling to this view—for which there is neither any excuse nor justification.

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.
¹

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.
²
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 different species unknown to science, but both male, and having sex.
³
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.
⁴

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.
⁵
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,
⁶
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,
⁷
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.
⁸

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.
⁹
The one on Malta lived eye-to-eye with a gigantic species of swan called
Cygnus falconeri
, with a wingspan of around three meters.
¹⁰
Micromammoths evolved on Wrangel Island in the Russian Arctic, where they outlived their larger mainland cousins by thousands of years.
¹¹

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.
¹²
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.