Data from: Three hundred years of low non-paternity in a human population

When cuckoldry is frequent we can expect fathers to withhold investment in offspring that may not be theirs. Human paternal investment can be substantial and is in line with observations from tens of thousands of conceptions that suggest that cuckoldry is rare in humans. The generality of this claim seems to be in question as the rate of cuckoldry varies across populations and studies have mostly been on Western populations. Two additional factors complicate our conclusions, (1) current estimates of the rate of cuckoldry in humans may not reflect our past behaviour as adultery can be concealed by the use of contraceptives; and (2) it is difficult to obtain samples that are random with respect to their paternity certainty. Studies that combine genealogies with Y-chromosome haplotyping are able to circumvent some of these problems by probing into humans’ historical behaviour. Here we use this approach to investigate 1273 conceptions over a period of 330 years in 23 families of the Afrikaner population in South Africa. We use haplotype frequency and diversity and coalescent simulations to show that the male population did not undergo a severe bottleneck and that paternity exclusion rates are high for this population. The rate of cuckoldry in this Western population was 0.9% (95% confidence interval 0.4–1.5%), and we argue that given the current data on historical populations we have to conclude that, at least for Western human populations, cuckoldry rate is probably in the range of 1%.当婚外父权（cuckoldry）发生频率较高时，父亲往往会减少对可能并非亲生的后代的抚育投入。人类的父系抚育投入往往十分可观，而数万例受孕案例的观测结果也显示，人类群体中的婚外父权现象较为罕见。但这一结论的普适性尚存争议：一方面，不同人群的婚外父权发生率存在显著差异；另一方面，现有相关研究大多仅针对西方人群展开。另有两项因素进一步使研究结论的可靠性复杂化：其一，由于避孕手段可掩盖通奸行为，当前对人类婚外父权发生率的估算或许无法反映人类过往的实际行为模式；其二，难以获取与父权确定性无关的随机抽样样本。将谱系记录与Y染色体单倍型分型（Y-chromosome haplotyping）相结合的研究，可通过追溯人类历史行为规避上述部分局限。本研究即采用该方法，对南非阿非利卡人（Afrikaner）群体23个家族中跨越330年的1273例受孕案例展开分析。我们借助单倍型频率、单倍型多样性数据以及溯祖模拟（coalescent simulations）证实，该男性人群未经历剧烈的种群瓶颈效应，且本群体的父权排除率较高。该西方人群的婚外父权发生率为0.9%（95%置信区间：0.4%~1.5%）。基于现有历史人群研究数据，我们认为至少针对西方人类群体而言，婚外父权发生率大概率处于1%左右的区间内。