The Accidental Species: Misunderstandings of Human Evolution (16 page)

Pithecanthropus
showed an interesting combination of somewhat humanlike limb bones but a skull rather smaller than that of modern humans.
Pithecanthropus
could be seen as an intermediate between apes and humans, but ran against the prevailing theoretical view that as modern humans are distinguished by big brains, then it must have been the case that big brains evolved first, before humans learned to stand fully erect. As the musician George Clinton once memorably put it in another context—free your mind and your ass will follow.
Pithecanthropus
was therefore generally seen as an apish side issue, perhaps
a giant gibbon, but not anything especially close to human ancestry. Thus was a mark made for the second of the two conventional reactions to new discoveries of members of the human family: if it’s not a diseased human, then it must be some kind of ape.

The most important and influential fossil hominin discovery ever made was a skull and jaw of a fossil human from a gravel pit in Piltdown, in southern England, in 1912.
²³
The skull was undeniably old, as shown by fossils of ancient mammals found in the same gravels, but it looked remarkably modern. The jawbone, assumed to have been associated with the skull, looked very apelike, with a receding chin. The dynamite combination of modern-looking skull and primitive jaw showed that the brain had, indeed, led the way in human evolution, dragging the brutish body after it.

It might be no coincidence that the heyday of Piltdown Man coincided with the nadir of Darwinism. Piltdown came at just the right time to fall victim to the vacuous storytelling as condemned by scientists such as William Bateson. If distinguished anthropologists, who ought to know, assure us that natural selection drove the evolution of the brain before all else, then, in short, it did, and that was that.
Eoanthropus
was orthodoxy for a generation, the fossil against which all others would be judged.

Eoanthropus
had had a clear run for more than a decade when the first evidence for human evolution in Africa turned up. The discovery threatened to overturn the now-established view of the “Piltdown committee”—the London-based group of grandees whose opinions on human evolution went unchallenged.
²⁴
The report came from Raymond Dart, an Australian-born medical scientist at the fledgling University of the Witwatersrand in South Africa. Dart had been sent a crate full of fossils blasted out of a lime works at Taung in the Transvaal. One of the fossils was the cast of a brain of a small, apelike creature. Another was the skeleton of the face that hafted onto the brain cast, as snugly as a cricket ball in a wicket keeper’s mitt.
²⁵
Dart, who had been taught neuroanatomy in London by another expat Australian, Grafton Elliot Smith—one of the Piltdown committee—immediately grasped the significance of the find. This was not an ape, but a child of a new species, intermediate between apes and modern humans. Dart sent a preliminary description of the find to
Nature
, where
Australopithecus africanus
(southern ape from Africa) was published.
²⁶

The reaction to the Taung “baby” was immediate and negative. Let
ters sent to
Nature
from the various members of the Piltdown committee, including Dart’s mentor, Grafton Elliot Smith, damned Dart’s finding with faint praise.
²⁷
Yes, the finding was important, but fossils of juveniles are always hard to judge, they said. Humans and chimps look far more alike as babies than they do as adults, so the Taung baby could be an infant ape just as well as an infant ape-man. The Piltdown committee effectively suppressed the publication of Dart’s subsequent monograph, which contained much evidence in favor of the ape-man hypothesis that was either incompletely considered or not available when Dart sent his short communiqué to
Nature
. In 1929, the Royal Society in London rejected the monograph for publication—the referees certainly included members of the Piltdown committee—and the manuscript lay ever afterward buried with Dart’s papers at the University of the Witwatersrand. Would paleoanthropology have been changed had the monograph been published? It’s impossible to say.

Dart’s salvation came in the form of more fossils to back up his ideas. Robert Broom—a paleontologist and a rather more intrepid character than Dart—saw the Taung fossil for himself, and reported to
Nature
that it was precisely as Dart had said it was.
²⁸
Although Broom had had the advantage over the Piltdown committee of actually having seen the fossil for himself, it took Broom’s discoveries of several more fossil hominins
²⁹
from cave deposits in South Africa for the idea of ape-men to take hold.

Broom’s hominins were a varied lot. Although no more fossils were forthcoming from Taung, fossils of what looked like adult versions of
Australopithecus africanus
came from an ancient cave called Sterkfontein, whereas fossils of a rather different creature, eventually called
Australopithecus
(or
Paranthropus
)
robustus
, emerged from other sites, Swartkrans and Kromdraai.
A. africanus
was slightly built, with somewhat humanlike teeth not specialized for any diet in particular.
A. robustus
, in contrast, had massive jaws and big, blocky teeth, perhaps more suitable for a diet of tough vegetation such as roots, seeds, and nuts. Broom’s almost single-handed barrage of papers on these creatures to
Nature
from the mid-1930s onward was largely responsible for rehabilitating Dart’s reputation.
³⁰

The variety of these finds should have been evidence enough that the human family was diverse, and that more than one kind of hominin existed at any one time: the first evidence that human evolution was uncertain and bushy, far from the single lineage I caricatured in
chapter 1
. At the time, however, the geological ages of these fossils was not known with any certainty. All the australopiths came from cave deposits, which are invariably a jumble of things that have fallen in, or were brought in by predators at various times. Even today, getting reliable dates for fossils found in caves is a difficult business, and that’s with the battery of modern techniques for dating that hadn’t been invented in Broom’s day.

As more and more fossils came to light, it became clearer that the australopiths did not conform to the George Clinton model of evolution. They had rather small brains, but would have walked erect—the precise opposite of the model espoused by the Piltdown committee.

Further evidence came from China in the late 1920s and early 1930s, at a site called Dragon-Bone Cave (Chou Kou Tien, modern-day Zhoukoudian), where a Canadian called Davidson Black and his colleagues reported fossils of a creature they called
Sinanthropus
.
³¹
“Peking Man” had a larger brain than
Australopithecus
, but smaller than modern humans.
³²
Sinanthropus
was associated with stone tools, and perhaps even the controlled use of fire—hallmarks, it was thought, of technology, and therefore of humanlike activity.
³³
Sinanthropus
was later shown to be very similar to Dubois’s
Pithecanthropus
from Java,
³⁴
and the two were united into one species,
Homo erectus
—the Man who stands upright.

By the late 1930s, a picture of early human evolution was beginning to emerge that has remained intact, more or less, ever since. The earliest members of the human family evolved in Africa, and were typified by forms such as
Australopithecus
—rather apelike, with small brains, but which nevertheless walked upright. Later on, hominins dispersed into Eurasia, acquired tools and a certain stature, and became
Homo erectus
—with a brain larger than those of australopiths, but smaller than in modern humans.
Homo erectus
walked upright. His name said as much.

The steady accumulation of evidence made Piltdown Man look like an increasingly anomalous side issue, ever harder to fit into evidence that challenged the preconceptions of the experts. Big-brained Piltdown might have had some support from Neanderthal Man, which had, if anything, a larger brain than seen in modern humans—an inconvenient fact that is usually brushed aside in the canonical picture of acquisition and improvement. Neanderthals were also seen as stooped and shambling, as Piltdown was meant to have been. But the skulls of Neanderthals, while large, are very distinctive, and quite different from those of modern humans. And the picture of Neanderthals as stooped
comes from the interpretation of just one skeleton, of an elderly male crippled with arthritis. In reality, Neanderthals stood as erect as any healthy modern human. Piltdown stood alone.

Eventually, the penny dropped. As the years wore on, it became ever clearer that Piltdown was not so much anomalous as embarrassing. In 1953, proof came of what many had already come to suspect, that Piltdown Man was a fraud.
³⁵
The skull looked like that of a modern human because it was one. The apelike jaw had come from an orangutan. The joint where the jawbone would have attached to the skull had been broken, so nobody could have seen that the two didn’t fit together. The teeth in the orangutan jaw had been filed down so that they didn’t look so apish to have given the game away, and the whole arrangement had been stained to make the bones look very old. The gravel pit at Piltdown had been salted with bones of archaic mammals from elsewhere.

The identity of the hoaxer remains unknown to this day. There has been some suggestion that it was one Martin Hinton,
³⁶
an expert on fossil rodents at the Natural History Museum, who had the means and the technical knowledge, and also a motive: a grudge against Arthur Smith-Woodward, his boss, a prominent paleontologist—and a leading light on the Piltdown committee, and a critic of Dart’s
Australopithecus
.

Whoever was responsible, the joke went far too well—perhaps so well that there was no possibility of a safe confession for the hoaxer. Smith-Woodward and his cronies bought the story without question. Further “finds” at Piltdown relating to the “First Englishman” included a hunk of bone deliberately carved into the shape of a cricket bat, clearly meant to be so ridiculous that someone, surely, would have suspected something. This, too, was treated as genuine.

At the risk of laying it on with a trowel, the moral is that it is very easy to see fossil evidence (or, indeed, any scientific evidence) through the highly selective and distorting lenses of one’s deeply held preconceptions, rather than for what it plainly is. If I have gone on about it at some length, that’s because it can be seen as the message for this whole chapter, that the discoveries made in the course of shedding light on human prehistory have a habit of challenging preconceptions—and indeed for this whole book, that when looked at dispassionately, many if not all the attributes we think of as distinctly human are in fact nothing of the kind, and even if they are unique to humans, this uniqueness is in itself nothing special.

With the final unraveling of Piltdown the focus moved back to Af
rica, and the name of Leakey. Louis Leakey, the son of a missionary who came to preach the gospel to the Kikuyu, soon became fascinated with the search for what he called in a later book “Adam’s ancestors.”
³⁷
The search was long, hard, and, for thirty years, mostly fruitless. In 1959, however, Leakey’s wife, Mary, discovered the skull of a fossil hominin at Olduvai Gorge in what is now Tanzania.
³⁸
This creature was
Zinjanthropus boisei
, a robust australopith, similar to
Australopithecus robustus
from South Africa. (These days many paleoanthropologists prefer to group all robust australopiths together in a separate genus,
Paranthropus
, so that
A. robustus
is
Paranthropus robustus
and Leakey’s “Zinj” is
Paranthropus boisei
.)

In 1964, Leakey announced the discovery of what he claimed to be the earliest evidence for the genus
Homo
. This was
Homo habilis
(handy man).
³⁹
The name was attached to a second hominin discovered at Olduvai, less robust than “Zinj.”

Although Leakey’s 1964 paper describing
Homo habilis
was very careful, laying out technical statements on the anatomy of the genus
Homo
in general and the species
Homo habilis
in particular, the presumption was clear: if
Homo habilis
and
Zinjanthropus
were at the same site, associated with stone tools, then
habilis
, with its larger brain, was probably the toolmaker. “When the skull of
Australopithecus
(
Zinjanthropus
)
boisei
was found on a living floor at F. L. K. I,” wrote Leakey and colleagues,

no remains of any other type of hominid were known from the early part of the Olduvai sequence. It seemed reasonable, therefore, to assume that the skull represented the makers of the Oldowan [stone tool] culture. The subsequent discovery of remains of
Homo habilis
in association with the Oldowan culture at three other sites has considerably altered the position. While it is possible that
Zinjanthropus
and
Homo habilis
both made stone tools, it is probable that the latter was the more advanced tool maker and that the
Zinjanthropus
skull represents an intruder (or a victim) on a
Homo habilis
living site.

Because you cannot reliably infer the behavior of an extinct creature from its bones, the whole definition of that creature, if encountered as a fossil but classified according to its presumed behavior, becomes debatable. The fossils we have are fragmentary. One debate centers on whether there is one species of early
Homo
—
Homo habilis
—or two, the other being
Homo rudolfensis
, a name attached to a skull discovered in
1972 by Bernard Ngeneo—a member of the research team led by Leakey’s son, Richard—at Koobi Fora on the eastern shore of Lake Turkana in Kenya.
⁴⁰
A third species of early
Homo
was recently added to the mix. This is a skull discovered in 1977 from Sterkfontein, a site famous for its australopiths. The skull was originally assigned to
Homo habilis
but has now been renamed
Homo gautengensis
.
⁴¹