Figure 2.

Comparison of the predictive power of the average vocalization models, by vocalization type (short, greeting and roar). (a) Cameroonian women, (b) Hadza women, (c) Cameroonian men and (d) Hadza men. Regression lines represent the association between actual hand grip strength (measured HGS, averaged between right and left hand) and the predicted HGS from the final average model from each type of vocalization. ****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05. (Online version in colour.)