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.