American Scientist

BORN IN AFRICA: The Quest for the Origins of Human Life. Martin Meredith. xxiv + 230 pp. Public Affairs, 2011. $26.99.

THE FOSSIL CHRONICLES: How Two Controversial Discoveries Changed Our View of Human Evolution. Dean Falk. xiv + 259 pp. University of California Press, 2011. $34.95.

Born in Africa, by Martin Meredith, and The Fossil Chronicles, by Dean Falk, are two very different books. Meredith is a journalist and historian, and his book examines the history of human evolutionary studies, primarily in Africa, providing a comprehensive overview of the conflicts between different researchers, different points of view and, sometimes, different evidence, mainly from the 1920s to the present. Falk is a scientist who has contributed significantly to the study of the evolution of the human brain, and she has been directly involved in some of those controversies. Her book—in contrast to Meredith’s, which explores numerous events in the history of paleoanthropology—focuses primarily on just two discoveries.

Despite their differences, Born in Africa and The Fossil Chronicles do overlap in subject matter and have similar themes. Both focus on controversies regarding which early hominin species (human ancestors) are like apes and which are like humans. And both discuss one of the earliest conflicts of this sort, the one between Raymond Dart (a colorful and controversial Australian based in South Africa) and members of the English scientific establishment, who disagreed over how to interpret a single fossil—the juvenile Australopithecine known as Taung. Early in the 20th century, Dart (the original describer of Taung) and Sir Arthur Keith (sponsor of the famous forged Piltdown fossil) were the Moon and the Sun of paleoanthropology and exerted a gravitational influence over the tides of hominin fossil interpretation. Falk is well known for her research on the brains of early Australopithecines, work that has centered on the Taung fossil. Her interpretations of this early find address the conflict between Dart and Keith, and in The Fossil Chronicles she spends several chapters discussing Dart’s research. But the bulk of the book consists of Falk’s assessment of various interpretations of the recently discovered, diminutive “Hobbit,” a hominin fossil found in 2003 on Flores Island in Indonesia. It was so unexpected a find that an old theme in human evolutionary studies soon resurfaced to explain it: Hobbit is so odd, some believe, that it must be a mutant or an abnormal form that can be explained by disease or dysfunction.

As a researcher in this field, I thoroughly enjoyed Meredith’s book. I had the opportunity to examine the original Taung fossil under the knowledgeable and entertaining guidance of Philip Tobias, who today holds the position originally held by Raymond Dart at the University of Witwatersrand in Johannesburg. The story of the Taung child—its discovery, its anatomy and the controversy surrounding it—is central to the human evolutionary story that Meredith is telling. Taung was brought to Dart’s attention and reported by him in the 1920s, when the British Piltdown fossils, now known to be forgeries, held sway as the archetype of our early human ancestors. There was a concept in the early 20th century of what a human ancestor would look like—it would have a large, humanlike brain, apelike teeth and an in-between body. And lo and behold, in 1912 a “fossil” fitting this description was found at Piltdown in southern England and was immediately established as physical dogma, despite the presence of what we now regard as obvious indicators that it was fake.

Taung’s brain and teeth were more apelike than those of “Piltdown Man,” but Taung’s body was more humanlike in that it was apparently configured for upright walking, and it could also be regarded as somewhat humanlike in other details. But Britain was a center of anthropology at the time and already had a very nice human ancestor, thank you very much. So for many years Dart’s work was variously sidelined, ignored and even ridiculed. It finally began to gain acceptance in the late 1940s after the discovery by Robert Broom of other Australopithecine fossils in South Africa, and in 1953, when Piltdown Man was revealed to be a hoax, Dart was further vindicated. These things happened just in time for two major events to occur: The study of human origins was decentralized, so that other people could play too, including the South Africans, the French and even the Americans; and anthropologists began discovering what would eventually be regarded as key fossils in Tanzania, Kenya and Ethiopia.

Born in Africa takes us through the days of Mary and Louis Leakey, and their real and intellectual heirs, Richard and Mauve Leakey; the discoveries of the Berkeley group, the most famous members of which were Donald Johanson (one of the discoverers of the Australopithecine hominin “Lucy”) and Tim White (who also worked on Lucy); and the work of increasingly internationalized and interdisciplinary teams of researchers addressing finer and finer questions about human evolution. Meredith’s account of all this is rich in detail. I thought I had already heard all of the scuttlebutt, but he has a few tidbits that were new to me. Most of the “interesting moments” I know about that he leaves out have more to do with the archaeological research than the fossil research.

And that brings me to the one minor criticism I’d like to make of Born in Africa . Meredith brings in the archaeological research related to human origins fairly late in his account, but it was important early on. For example, as artifacts cropped up both in Africa and in Europe, an entire pre-Oldowan time period, the Kafuan, was postulated that we now know never existed (what were initially thought to be Kafuan tools are now believed to be just rocks that had flaked naturally). And the question of which stone tools were associated with which specific hominins was argued about almost as much as some of the key questions about the fossils themselves.

The book’s take-home message is that personality conflicts, competing national interests, and competition over access to resources are more interesting than the story of human evolution itself, which has little flesh on it. It’s easy to feel the joys and heartaches of the actors in the drama; we empathize with the underdogs and are annoyed at the coyotes. Meredith does tell the human evolutionary story—but as a comedian once said of baby races, the real reason you are interested is to see the crashes.

Back when I was a graduate student in anthropology, I was asked by my adviser to absorb and comment on two sets of literature. The first had to do with the dating of strata in East Africa. Although scientists did not know it at the time, a particular layer of volcanic material was essentially undatable by the prevailing methods. Therefore, every time it was sampled in different localities, a different date was obtained, and great confusion resulted. That story is well covered by Meredith in his section on Koobi Fora.

The second set of literature was a series of papers written by Ralph Holloway and Dean Falk starting around 1981, in which they fought over the interpretation of early hominin brains as studied through endocasts—casts of the inside of an animal’s braincase that produce roundish blobs resembling the exterior of the original brain. Some endocasts form naturally when the cranial cavity of a skull fills with sand that becomes packed and fossilized, but more often they are artificially produced by pouring casting material into a skull. Endocasts are of limited value, because layers of tissue in a living mammal separate the brain from the skull, attenuating detail. As Falk explains in The Fossil Chronicles, they offer a rather “superficial” view of a brain. But they are not without their uses. Endocasts of fossils are compared with endocasts made from the skulls of modern primates and humans, which in turn are understood via other forms of neuroanatomy. We can look at brain scans of primates and humans during their activities and see that a certain area of the brain is activated during the performance of a certain kind of task. If the region activated is one that is larger in humans than in monkeys and has to do with something more relevant to human behavior than to monkey behavior, then we might infer that enlargement of this region in the endocast of an extinct hominin indicates humanlike behavior, or that a lack of enlargement indicates a lack of humanlike behavior.

The academic fight between Holloway and Falk was typical of the 1980s. Falk was a woman working in a largely male field, and some people wondered whether Holloway might be trying to marginalize her for that reason. He was fond of pointing out that she was wrong in part because a lot of very smart and well-established people said things contrary to her findings. Anyone interested in a study of both gender bias and the ad hominem argument in science would do well to look at these papers.

Around this time arguments over how to distinguish what is humanlike from what is apelike were also emerging in the study of growth rates, teeth and other features of various hominin remains, and in relation to the question of how childhood evolved. The timing of growth and development in modern humans is different from that in our nearest living relatives, the nonhuman apes, and much of this has to do with the extended period of development that we call childhood. Childhood includes an extended period of neural development during which our brains take on all those humanlike characteristics that make us distinct from the other apes.

The Holloway-Falk argument was over whether the brains of Australopithecines were apelike or humanlike, and this is exactly the same argument that was central to the Taung-Piltdown comparison and to Raymond Dart’s research. Falk’s analysis is too nuanced and complex to be fully explained in this review; you’ll need to read her book to find out how it goes. But we now think that Australopiths were mostly apelike, although not entirely so, and that unambiguous members of the genus Homo, such as Homo erectus, were mostly, but not entirely, humanlike. Falk’s book would be worth reading just to get her perspective on this historically important debate.

But the most important part of The Fossil Chronicles is Falk’s interpretation of the meaning of the small-brained fossil hominin known as Hobbit. Its discovery on the island of Flores in Indonesia in 2003 was one of the most important finds of the past hundred years; fragments of at least seven other similar skeletons were unearthed in the same cave, along with rather advanced stone tools and butchered and charred animal bones. This newly discovered species, Homo floresiensis, appears to have lived as other premodern hominins may have done, hunting, scavenging and gathering. Nothing like it was thought to exist: As far as we knew, there had been no small-brained bipedal apes anywhere at any time during the past 1.5 million years. But Hobbit appears to have lived between 94,000 and 12,000 years ago. The world of Homo floresiensis is a little like a quaint historical neighborhood that has been left alone by modern development because it lies off the beaten track on the edge of some large city. One wonders, given the reality of the Flores find, whether the world may once have been (partly) populated by additional species as different from the main line of human evolution as Hobbit—hominins who were displaced quickly and completely enough that we happen not to have run into them.

Falk has conducted studies of both a virtual endocast of Hobbit and an artificial one. Because the female Hobbit and the fossils found with her are so unusual, it has been suggested that their peculiarities are attributable to some disease or abnormality, such as microcephaly. The preponderance of evidence, including Falk’s work, rules out all such explanations. Homo floresiensis is normal, although very different than expected, just as Taung was different than expected.

And that is how the stories told by Meredith and Falk fold into each other: The history of the study of human evolution shows that surprising findings make well-educated and otherwise rational people behave irrationally for a time, until everyone eventually settles on a new view.

Falk’s discussion of Hobbit and all that that fossil implies is rich in detail and extensive. I’ll end with this especially interesting if somewhat quirky finding: Falk and her team determined that the brain of Hobbit is most like that of a small Homo erectus, suggesting that either Homo floresiensis is a diminutive form of Homo erectus or the two hominins shared an early evolutionary history. Hobbit’s brain has an enlargement of the region known as Brodmann’s area 10. Humans have an enlarged Brodmann’s area 10 as well, but Hobbit’s may be even larger relative to her overall brain size. Falk makes this rather daring suggestion: If you were a small hominin living on an island populated by dragons, you’d want a large Brodmann’s area 10, because it would give you both the ability to preimagine escape plans in the event of an attack and the ability to keep track of your surroundings while you are busy making stone tools or gathering plants. The world Homo floresiensis lived in was indeed inhabited by dragons, a form of monitor lizard known to us today as the Komodo dragon. These creatures, which are carnivorous, are often more than three meters long and have been known to ambush hunters. The archaeological evidence suggests that these hominins hunted, cooked and ate Komodo dragons, and the endocast evidence indirectly suggests that the dragons may have hunted the hominins as well.

I recommend both these books, and I suggest that you read them together, starting with Meredith and finishing with Falk.

Greg Laden is a biological anthropologist who has worked in the Democratic Republic of Congo and South Africa. He writes a blog at Scienceblogs.com.