Data from: Sex ratio effects on reproductive strategies in humans

Characterizations of coy females and ardent males are rooted in models of sexual selection that are increasingly outdated. Evolutionary feedbacks can strongly influence the sex roles and subsequent patterns of sex differentiated investment in mating effort, with a key component being the adult sex ratio (ASR). Using data from eight Makushi communities of southern Guyana, characterized by varying ASRs contingent on migration, we show that even within a single ethnic group, male mating effort varies in predictable ways with the ASR. At male-biased sex ratios, men's and women's investment in mating effort are indistinguishable; only when men are in the minority are they more inclined towards short-term, low investment relationships than women. Our results support the behavioural ecological tenet that reproductive strategies are predictable and contingent on varying situational factors.学界关于“腼腆雌性与热忱雄性”的行为特质界定，植根于日渐过时的性选择理论模型。进化反馈可显著塑造性别角色，以及后续交配投入的性别分化模式，其中关键影响因素便是成年性别比（Adult Sex Ratio, ASR）。本研究使用圭亚那南部8个马库希（Makushi）族群社区的数据——这些社区的成年性别比随移民情况而存在差异——证实：即便在同一族群内部，雄性的交配投入会随着成年性别比呈现出可预测的变化规律。当性别比偏向雄性时，两性在交配投入上并无显著差异；仅当雄性占种群少数时，雄性才会比雌性更倾向于建立短期、低投入的伴侣关系。本研究结果佐证了行为生态学的核心信条：繁殖策略具备可预测性，且会随具体情境因素的变化而发生改变。