Cavalli-Sforza edited a book on African Pygmies. He claimed that pygmy stature was related to a hot humid climate in the rainforest. There are various weaknesses in this theory. Modelling does not support the suggestion that the Pygmy body form, with short limbs, especially legs, will be advantageous in such a climate. Nor do actual experiments on heat relations of Bantu and Pygmy people in humid conditions and during exercise in hot conditions. If anything, Pygmies are worse off in such hot conditions.

Another weakness with the heat relations theory of Pygmy/Negrito stature is that many such people live in cool, mountainous rainforests in places like New Guinea and the Philippines.

I have published a theory that the small skeleton (and hence body size) of such people is related to low ultraviolet light levels under the rainforest canopy (they ARE low - I've measured them in North Queensland rainforest). Low UV means low vitamin D production in the skin, especially dark skin, and therefore reduced calcium uptake for skeletal growth and maintenance. I have also suggested that the "Hobbits" of Flores were simply extreme versions of the pygmoid body type, developing over a long time in rainforest. They were probably derived from Homo sapiens, possibly archaic Homo sapiens.

Julian