Fig. 2
Female population size from year 500 to year 1000 (a) and from year 1000 to year 1500 (b), in a model where density-dependent mechanisms operate only on the duration of post-partum amenorrhea, while age at menarche is kept constant at 17 years (broken line), in a model where density-dependent mechanisms operate only on the age at menarche, while the mean age of post-partum amenorrhea is kept constant at 19 months (dotted line), and in a model in which both mechanisms are operating (unbroken line). (c) Time development of the mean age at menarche in a model where the environment resources term increases abruptly from 1 to 8 at 500 years (broken line), or linearly from 1 to 8 from year 500 to year 600 (unbroken line).
