The Rampasasa Pygmy Somatology Expedition

The interest in the biology of human pygmies did not begin with the Liang Bua find; it's been going on for awhile. The symptoms include Cavalli-Sforza's edited volume on the African Pygmies, genetic sampling of pygmy peoples of Africa in order to examine their relationships with other populations, and the question of whether the Negritos of southeast Asia may be related to some early dispersal of modern humans out of Africa. But the Homo floresiensis story has increased the interest level. It is in this context that I link to Carl Zimmer's post on the state of current Indonesian pygmy anthropology on Flores.

The fact that there are now pygmies in the region is not irrelevant to the interpretation of LB 1. They reemphasize the problem that human pygmy populations do not have australopithecine-sized brains, and focus attention on selective factors that would reduce body size in humans. I have only a couple of comments.

The team got back from Flores on April 25. While there, they went to a village called Rampasasa, made up of 77 families. About 80% of the people were pygmies. They measured 10 people who were a bit taller, with a height of 155 cm and 2 measuring 160 cm. Homo floresiensis was 130 cm. The researchers claim that these tall villagers got some extra height from having married non-pygmies from surrounding villages.

We hear often of African pygmy populations that the stature of individuals has been increasing due to intermarriage with neighboring non-pygmy groups (often Bantus in Central Africa). This is certainly credible. It is also credible that the selective factors favoring pygmy size have been relaxed in recent, historic pygmies. If so, then alleles introduced by intermarriage would face less disadvantage and therefore spread more easily. There may even be advantages to taller stature today that are no longer outweighed by selection for smaller stature.

The source of this selection in human pygmies is plainly unknown. Energetics, themoregulation, and ecology have all been suggested, but there has been no real test of any hypothesis. Some of the mechanisms for pygmism are better known, in particular in relation to the growth hormone receptor (GHR).

So it is possible that the Flores pygmies or other Indonesian pygmy populations may formerly have been smaller in size.

It is also possible that LB 1 was taller than 130 cm. The talk at the meetings was that the stature estimates in the Nature paper had been misapplied, meaning that LB 1 should be considered to be considerably taller than 130 cm. Both possibilities reduce the weight of evidence suggesting that LB 1 was significantly small for a modern human. I don't think this thread is necessarily that significant because of the likelihood of pathology, but it does signal that the range of normal human variability should be considered more widely than has been the case.