Figure 3.

Interbirth intervals for Kanyawara chimpanzee females from 1983–2020. Sample includes only birth intervals following an infant that survived to age 4 or at least to the mother’s next conception and excludes intervals estimated by more than 3 months. The same intervals are plotted twice, once by their start year (orange, dashed line) and once by their end year (blue, solid line), each with third-order polynomial fits.