Fig. 1
The total female population size as a function of time over a 2000-year period (a). Mean age at menarche (b) and mean duration of post-partum amenorrhea (c) over this period. In (b) and (c), the mean values are plotted for the year of birth of the women. Figure (d) shows an index of the environment resources. The first 300–400 years should be regarded as a running-in period, and the simulation results are not plotted. The environment resources term in the model changes abruptly from 1 to 8 at 500 years, from 8 to 3 at 1000 years, and from 3 to 6 at 1500 years.
