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'Caldwell D, 2013: Hair distribution, immuno-resistance and adaptations to the first baby slings. Anthropologie (Brno) 51, 3: 349-374'. |
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| Abstract | | This essay contains two hypotheses: the first postulates that infectious and parasitic conditions in the first baby-carrying devices or "slings" selected for changes in juvenile hair distribution and immuno-resistance, and that a convergence of datable mutations and osteological changes indicate that infants in our lineage adapted to the microenvironment between 1.2 and 2.8 million years ago - with evidence converging towards the older end of that range. Such slings, which might have been first used to carry gleanings, would have surrounded offspring in dangerous pathogens and parasites. Babies whose foetal body baldness had not disappeared would have had an advantage over infants with previously normal body fur, because adults could clean them better - probably resulting in the neotenic extension of the foetal trait. The microenvironment might have selected for the elimination of infectious pathways as well. The inactivation of the CMAH gene, which could have provided a pathway for pathogens associated with ungulate and proboscidean hides to infect infants with diarrhea, is explored as a candidate, and multiple ways of testing the hypothesis are described. The related hypothesis, which is based partly on avian comparisons and milk chemistry, postulates that slings gradually forced adults to focus on the kind of nutrition needed by more slowly maturing infant brains by making their babies more altricial. This might have triggered more scavenging, hunting, and feedback mechanisms that slowly extended the new juvenile hair distribution to adults as part of a whole-body cooling system based on sweat and body baldness while contributing to speciation. | | | | Keywords | | Human evolution - Hominins - Neoteny - Parasites - Hair distribution - Baby slings - Mirror neurons - Motherese | | |
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