Researchers announced today that an excavation in Liang Bua cave on the Indonesian island of Flores has uncovered a new species of human, barely a meter tall, that lived as recently as 13,000 years ago. Christened Homo floresiensis, the hominid--known primarily from a partial skeleton known as LB1--had adult body and brain proportions comparable to those of the much older australopithecines, such as Lucy. Other features, however--including those related to chewing and walking--align it with our own genus, Homo. Describing the find in the October 28 Nature, Peter Brown of the University of New England in Armidale, Australia, and his colleagues surmise that H. floresiensis was a descendant of H. erectus. With H. sapiens arriving in eastern Asia by 35,000 years ago, and relic populations of H. erectus possibly persisting on nearby Java, three human species may have co-existed in this region not so long ago. Scientific American.com's editorial director, Kate Wong, spoke with Brown about the discovery. An abridged, edited transcript of their conversation follows.

KATE WONG: What brought you to Flores in the first place? I assume you weren't expecting to find something like this.

PETER BROWN: The work in Flores was initiated by Mike Morwood, who's in in my department [at the University of New England in Armidale, Australia]. He has a project looking at the evolution and migration of people through the Indonesian archipelago and in Australia. He was interested in Liang Bua, which is a cave on Flores, because of previous work by R. P. Soejono [of the Indonesian Center for Archaeology in Jakarta]. It's a beautiful, large rock shelter and it clearly had a deep deposit. But previous work had only looked at the upper Mesolithic layer--no one had tried to dig to the bottom. So Mike went back with a large team, as well as with Professor Soejono, and dug down to bedrock, in the course of which they found lots of stone tools and eventually came across this hominid skeleton.

KW: There's been a fair amount of controversy about the ages of various human fossils from Southeast asia. How did you date LB1 and how confident are you in the ages that you obtained?

PB: There's a large team of experts in various fields of dating--including radiocarbon dating, optically stimulated luminescence, uranium series, electron spin resonance--and these technniques were applied to the site. Fortunately, the results are consistent. The carbon found in close association with the skeleton is about 18,000 years old. And there are optically stimulated luminescence dates above and below, and a series of other dates going down toward the bottom of the deposit as well. They all appear to be consistent and nicely stratified, so you have a range from the bottom of the site at about 94,000 years ago, give or take a little bit, to the skeleton at about 18,000, again give or take some. So we're happy with the dating results.

KW: LB1 has such a tiny body and brain--as small as the smallest australopithecine on record. Did you ever think about assigning it to a new genus rather than just a new species?

PB: In the initial letter to Nature, that's exactly what I did. But I was persuaded on further rumination that it should be placed in the genus Homo. On initial examination I was impressed by the features it appeared to share with early [hominids] like Australopithecus, but other features were more like Homo. For instance, australopithecines have large, projecting facial skeletons (large molar and premolar teeth in particular), whereas the face of LB1 is much more similar to members of the genus Homo. So you have this very humanlike looking face stuck with this very, very small braincase--a brain size which would be small for a chimpanzee. Looking at the rest of the skeleton, it had a combination of things we would consider to be humanlike features combined with things which are found in some australopithecines. I decided that some of the similarities with australopithecines were probably due to small body size and the biomechanics of locomotion, rather than just representing phylogeny. In other words, it wasn't an australopithecine located in Asia. And other things, like thickened bone in the cranial vault and the shape of the brain case, are more like those in members of the genus Homo than like Australopithecus. So I dismissed Australopithecus for a variety of reasons and then did a balancing act. And when we thought that it was most likely a dwarfed example of Homo erectus, then I leaned toward putting it in the genus Homo rather than creating a new genus.

2 Comments

1. 1. PhilinSanJose 09:02 PM 7/22/09

   The hypothesis that LB1 was abberrant could also be rejected on the grounds that it's unlikely that a primitive society could nurture an individual this primitive to adulthood.
   The tools might be attributle to a more modern, but yet undiscovered species, that co-existed with LB1 from whom LB1 acquired the tools.
   LB1 may have persisted to more recent times, a situation that no remains have yet substantiated, hence, the oral history of Ebu Gogo may refer to LB1.

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2. 2. Arturex 04:49 PM 7/30/09

   LB1 is crearly an homo species. However, it could have evolved from many different ancestors. Also, it could have evolved there fro any primate ancestor that dwell on those days.

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