Fig. 4.

Increases in complementarities allow the evolution of dads. The plot shows the frequency of dads in two simulated populations of 2,000 males over 100,000 generations with nonpaternity held fixed at $\varphi =1/2$. Complementarities ($\kappa$ and $\mu$) begin at 0 and increase at two points in time: from 0 to $1/4$ around 2 Mya and from $1/4$ to $1/2$ around 400 kya. (Top) $Y_C=Y_D=2.5$. (Bottom) $Y_C=5$, $Y_D=2.5$. In both Top and Bottom, $x=5$, $A=20$, mutation probability = $10^{-4}$.