Facial morphology predicts male fitness and rank but not survival in Second World War Finnish soldiers

Abstract

We investigated fitness, military rank and survival of facial phenotypes in large-scale warfare using 795 Finnish soldiers who fought in the Winter War (1939-1940). We measured facial width-to-height ratio-a trait known to predict aggressive behaviour in males-and assessed whether facial morphology could predict survival, lifetime reproductive success (LRS) and social status. We found no difference in survival along the phenotypic gradient, however, wider-faced individuals had greater LRS, but achieved a lower military rank.

Keywords: facial morphology; lifetime reproductive success; social dominance; survival; war.

Figure 1.

Example of measurements of fWHR as upper bizygomatic width (line a–b) versus facial height (c–d) in a fallen Finnish soldier. (available at source)

Figure 2.

Finnish troops who participated in the Winter War 1939–1940 and the distribution of (a) scaled fWHR, (b) predicted probability of surviving the Winter War (adjusted so the posterior mode at mean face width is 0.85). Figure contains all 795 individuals, see the electronic supplementary material, S3 for figure with three main regiments only. (c) Total number of children for fallen soldiers and (d) probability of attaining a rank depending on fWHR. Facial width increases with values (for an enlarged version of figure 2c see electronic supplementary material, S4). Dark shaded area represents 50% highest posterior density region and light shaded area represents 95% highest posterior density region.