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Allometry of primate hair density and the evolution of human hairlessness
Author(s) -
Schwartz Gary G.,
Rosenblum Leonard A.
Publication year - 1981
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330550103
Subject(s) - allometry , primate , adaptation (eye) , biology , grassland , hominidae , denudation , zoology , ecology , biological evolution , paleontology , genetics , tectonics , neuroscience
Allometric analyses of hair densities in 23 anthropoid primate taxa reveal that increasingly massive primates have systematically fewer hairs per equal unit of body surface. Considering the absence of effective sweating in monkeys and apes, the negative allometry of relative hair density may represent an architectural adaptation to thermal constraints imposed by the decreasing ratios of surface area to volume in progressively massive primates. Judging by estimates of body volume, denudation of the earliest hominids should have progressed to a considerable extent prior to their shift from a forest to a grassland habitat during the Pliocene. We propose that, lacking a reflective coat of hair, the exploitation of eccrine sweating emerged as the primary mechanism for adaptation to the increased heat loads of man's new environment and permitted further reduction of the remnant coat to its present vestigial condition.