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Characterizations of coy females and ardent males are rooted in models of sexual selection that are increasingly outdated.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.

“腼腆雌性与狂热雄性”的特质描述，根植于日渐过时的性选择（sexual selection）模型体系之中。进化反馈可显著影响性角色格局，以及后续的性别差异化交配投入模式，其中核心调控要素为成年性别比（adult sex ratio, ASR）。本研究依托圭亚那南部8个马库西（Makushi）族群社区的调查数据展开分析，这些社区的成年性别比随移民情况存在显著差异。结果表明，即便在同一族群内部，雄性的交配投入也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，两性的交配投入并无显著差异；仅当雄性在该族群中占少数时，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。