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the fossil chronicles

15 december 2012

In The Fossil Chronicles, Dean Falk notes that the most important discoveries of fossils on or near the human lineage have all been met with ridicule. Neandertal Man was disparaged as a Cossack with rickets. Homo erectus, when first unearthed in Java, was suspected of being a "microcephalic idiot" (137). So too with the joint subjects of Falk's recent book: Australopithecus africanus in the 1920s, and Homo floresiensis in the 2000s.

Yet when you think of it: somebody finds a new and wonderful fossil. What are the odds that this fossil also represents a rare anomaly among its species? Fossils of ancient humans are so exceedingly rare to begin with that it's almost unimaginable that a key find would be from a tiny subset of the modern-human population. Still odder would be the case if all these famous fossils were equally anomalous.

The more parsimonious explanation is that these fossils fairly represent their species (given that those species are variable to begin with, and that some of the fossils are clearly those of juveniles). But the parsimonious explanation sometimes beggars belief. Of H. floresiensis, one of its principal early researchers, Peter Brown, remarked: "I would have been less surprised if someone had uncovered an alien" (161).

Brown's quip is not really a joke, or even much of an overstatement. Grey beings from space fit into our worldview. So do hobbits, especially in the holiday-movie season of 2012 – H. floresiensis is called by Dean and many other researchers simply "Hobbit" – but they fit into the "long ago and far away" part of our imagination. And living Indonesian hobbits of not that long ago (17,000 years is Falk's estimate) are not part of anything ever contemplated in Western fiction.

Tantalizingly, hobbits are a part of Floresian folklore. People in Flores tell of little people, ebu gogo, uncomfortably omnivorous parahumans who could echo language but not get along with Homo sapiens very constructively – and who died out about 200 years ago (162-63). The people in Flores might have gotten wind of H. floresiensis and be having Western researchers on. And many cultures have traditions of little people in their woods. But the coincidence of these traditions with these fossil sites is eerie, to say the least.

For the systematics of human evolution, Homo floresiensis poses the damndest possible set of problems. Till the hobbits burst on the scene, the accepted wisdom was that both hominins, and later true humans, had evolved in Africa, and radiated from that continent across Asia in two waves. One species, emerging roughly 1.5 million years ago, was Homo erectus, first known from Java and China, but now pretty firmly seen as originating in Africa and migrating in leisurely fashion across Eurasia. The second is us, Homo sapiens, all of 200,000 years old, taking a similar route out of Africa to displace and replace our elder cousins.

Meanwhile, the still elder hominins that populate our ancestral tree, including all species of Australopithecus, have been seen as a strictly African phenomenon, akin (like us) at a great distance to the African great apes. But H. floresiensis looks like Australopithecus in many ways. What gives? At first hobbits were seen as island-bound dwarf versions of Homo erectus, which squares well with the undoubted presence of H. erectus elsewhere in Indonesia. But if they really descended from H. erectus, Falk explains, they'd have to have "devolved" australopithecine characteristics – something that would be weirder than finding microcephalics or aliens.

The inescapable (but hardly incontrovertible) conclusion is that australopithecines of some sort also radiated out of Africa, earlier than Homo erectus. Some of them filtered down into the Indonesian archipelago and hung out there for truly God knows how many millions of years, succumbing to disaster or competition from late-arriving H. sapiens just 17,000, or possibly even 200, years ago. (Falk also cites recent research suggesting that Homo erectus survived in Indonesia till just 27,000 years ago; all these suggestions, just ten years ago, would have been considered hilariously absurd.)

The history of humans is much stranger than we know, and Dean Falk, in a smart conclusion, allows as how it's only going to get stranger as we learn more. Much of her book is devoted to a chronicling of academic controversies (including some interesting speculation on the motives for such controversies in her field, which go much deeper, she suggests, than the usual haggling over grants and tenure and promotion). At times, Falk can be a little too cryptic in explaining her work in paleoneurology to a lay public. And sometimes she spends a page or two breathlessly recounting some news release or press conference that everybody else forgot about ten minutes after it happened. But overall, the book is an exciting introduction to the science of hobbits. To make weight, Falk includes several chapters on Raymond Dart and A. africanus, but it's not mere padding; she is interested in how Dart's professional travails over his epochal discovery parallel later controversies in paleoanthropology. It's good history of science, and thought-provoking popular nonfiction.

Falk, Dean. The Fossil Chronicles: How two controversial discoveries changed our view of human evolution. Berkeley: University of California Press, 2011.