Factors influencing infant sex ratio in howler monkeys (Alouatta spp.): A literature review and analysis.

Objective: Frequency-dependent selection is expected to maintain infant sex ratios around parity over evolutionary time. However, over ecological time periods, infant sex ratios vary, and it has been proposed that this variation may reflect adaptive processes. In primates, there are consistent patterns of variation in infant sex ratios, although their adaptive significance remains contentious.