title: Was plio-pleistocene hominid brain expansion a pleiotropic effect of adaptation to heat stress?
abstract: This paper examines the hypothesis (Fiałkowski 1978, 1986) that hominid brain expansion was largely a side effect of an evolutionary response to increased heat stress under conditions of primitive hunting, with reduction in reliability of brain components due to a rise in temperature having been offset by increases in the number of cerebral sub-units and interconnections among them. Fiałkowski's hypothesis is shown here to be based on measurements that are seriously inaccurate, and the explanatory mechanism to be contradicted by existing data on response to heat stress by smaller-brained nonhuman primates.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001833:Body Temperature Regulation; D001921:Brain / Q000033:anatomy & histology*; D000882:Haplorhini / Q000033:anatomy & histology*; D006801:Humans