Bipedality and hair loss in human evolution revisited: The impact of altitude and activity scheduling

Tamas David-Barrett*, Robin I. M. Dunbar

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
222 Downloads (Pure)

Abstract

Bipedality evolved early in hominin evolution, and at some point was associated with hair loss over most of the body. One classic explanation (Wheeler 1984: J. Hum. Evol. 13, 91-98) was that these traits evolved to reduce heat overload when australopiths were foraging in more open tropical habitats where they were exposed to the direct effects of sunlight at midday. A recent critique of this model (Ruxton & Wilkinson 2011a: Proc. Natl. Acad. Sci. USA 108, 20965-20969) argued that it ignored the endogenous costs of heat generated by locomotion, and concluded that only hair loss provided a significant reduction in heat load. We add two crucial corrections to this model (the altitude. at which australopiths actually lived and activity scheduling) and show that when these are included there are substantial reductions in heat load for bipedal locomotion even for furred animals. In addition, we add one further consideration to the model: we extend the analysis across the full 24 h day, and show that fur loss could not have evolved until much later because of the thermoregulatory costs this would have incurred at the altitudes where australopiths actually lived. Fur loss is most likely associated with the exploitation of open habitats at much lower altitudes at a much later date by the genus Homo. (C) 2016 The Authors. Published by Elsevier Ltd.

Original languageEnglish
Pages (from-to)72-82
Number of pages11
JournalJOURNAL OF HUMAN EVOLUTION
Volume94
DOIs
Publication statusPublished - May 2016
MoE publication typeA1 Journal article-refereed

Keywords

  • Australopiths
  • Thermoregulation
  • Incident radiation
  • Ambient temperature
  • Activity patterns
  • EARLY HOMININS
  • HOMO-ERECTUS
  • THERMOREGULATORY ADVANTAGES
  • ARDIPITHECUS-RAMIDUS
  • BEHAVIORAL ECOLOGY
  • MODELING APPROACH
  • ENERGETICS
  • PLIOCENE
  • ORIGIN
  • FIRE

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