A case for reduced skin sensation in high latitude prehistoric Polynesians

The cranial sensory nerve supply in three skeletal populations, two distinct prehistoric Polynesian groups from New Zealand, the Moriori and Maori, and one contemporary Indian group, are investigated. This paper assesses an aspect of the hypothesis that Polynesian groups have anatomical adaptations that enabled them to survive in a cool and wet environment. To this end the relationship between sensory nerve dimensions were examined, based on the area of cranial nerve foramina, and external environmental temperature. Statistical comparisons between the Polynesians and Indians showed significantly reduced cranial cutaneous sensory nerve foramina size, and therefore diminished facial cutaneous sensory nerve supply in the Polynesians. On this basis it is inferred that sensory supply to the skin of the infracranial body was also lessened. This paper proposes that reduced skin sensory nerve supply was selected as an adaptation to a cool and wet environment, where it acted as a body energy conserving mechanism by delaying the onset of body warming mechanisms.