Tuesday, November 18, 2008

Extinct: Hobbit

Human-like creatures, roughly the size of 3-year-olds, hunted pygmy elephants in Indonesia as recently as 18,000 years ago. Homo floresiensis (the real-life hobbit) is thought to have lived alongside modern humans on the now Indonesian island of Flores. The discovery of their diminutive bones in 2003 has sparked great controversy over whether "the hobbit" represents a new species or pathological variant of Homo sapiens (us). Our strange brethren, the "Man of Flores", is the latest installment in our Extinct series.

Charles Darwin developed his grand theory in part by examining islands, famously finches on the Galapagos. Islands - with isolated, naturally restricted populations - accentuate evolutionary pressures. They have fostered all manner of strange creatures from the dodo to the Komodo dragon (another Flores inhabitant). Australia's collection of beasts is curious island evolution writ large.

Which is to say - if a mysterious, tiny, recently extinct people was going to be found, it's not surprising that it would be on an island. Nevertheless, the 2003 discovery in Liang Bua Cave on Flores was breathtaking. Paleoanthropologists researching human migration found parts of a miniature hominid skeleton - what appeared to be a small-bodied, small-brained new Homo species. As the search continued, they found pieces of separate, similar skeletons including jaw and wrist bones. Stone tools (also small) and pygmy Stegodon bones (at least ironically small*) were found alongside some of the hominid bones. Astonishingly, the hominid skeletons were dated to as recent as 18,000 years ago, suggesting the hobbit lived alongside modern humans and that floresiensis, not neanderthalensis, finished second in the race to evolution's great champion Homo sapiens (a little self-congratulation never hurts).

Some scientists have theorized that Homo floresiensis is not a new species but represents pathological Homo sapiens. They suggest the skeletons represent people who suffered microcephaly, a disorder rendering small heads and brains. Recent intriguing studies using CT scanning of skulls and analysis of wrist structure refute this theory and support the separate species contention.

PBS's Nova recently aired a program on Homo floresiensis called "Alien From Earth". You can watch it here.

*It's possible the pygmy Stegodon and Homo floresiensis experienced convergent evolution, in which unrelated species develop the same trait. Flores might have shrunk them both, though this theory, like everything with the mysterious hobbit, is much disputed.

(image credit: representation of male Homo floresiensis with stylish crew cut; skulls of Homo floresiensis and Homo sapiens, from National Geographic)