The thermoregulatory function of the human hand: How do palm and digit proportions affect heat loss?

OBJECTIVES: The current study assessed whether ecogeographical patterns seen in hand proportions correlate with heat loss directly. Using a brief severe cold immersion experiment on the hand, the influence of hand and digit dimensions on heat loss was evaluated.

MATERIALS AND METHODS: A sample of 113 living individuals were tested. Two-dimensional and three-dimensional scanning techniques were used to assess hand and digit dimensions. Thermal imaging analysis was used to quantify heat loss during a 3-min ice-water immersion of the hands.

RESULTS: When body size was accounted for, hand width and digit length relative to total hand length were significant predictors of heat loss from the hand.

DISCUSSION: The current study provides empirical evidence to support the link between thermodynamic principles relating to surface area-to-volume ratio, and ecogeographical patterns associated with temperature.