In humans, most germline mutations are inherited from the father. This observation has been widely interpreted as reflecting the replication errors that accrue during spermatogenesis. If so, the male bias in mutation should be substantially lower in a closely related species with similar rates of spermatogonial stem cell divisions but a shorter mean age of reproduction. To test this hypothesis, we resequenced two 3–4 generation nuclear families (totaling 29 individuals) of olive baboons (Papio anubis), who reproduce at approximately 10 years of age on average, and analyzed the data in parallel with three 3-generation human pedigrees (26 individuals). We estimated a mutation rate per generation in baboons of 0.57×10⁻⁸ per base pair, approximately half that of humans. Strikingly, however, the degree of male bias in germline mutations is approximately 4:1, similar to that of humans—indeed, a similar male bias is seen across mammals that reproduce months, years, or decades after birth. These results mirror the finding in humans that the male mutation bias is stable with parental ages and cast further doubt on the assumption that germline mutations track cell divisions. Our mutation rate estimates for baboons raise a further puzzle, suggesting a divergence time between apes and Old World monkeys of 65 million years, too old to be consistent with the fossil record; reconciling them now requires not only a slowdown of the mutation rate per generation in humans but also in baboons.

在人类中，大多数种系突变是从父亲遗传的。这一观察结果被广泛解释为反映了精子发生过程中产生的复制错误。如果是这样，在精原干细胞分裂率相似但平均繁殖年龄较短的密切相关物种中，突变的雄性偏向性应该大大降低。为了检验这一假设，我们对橄榄狒狒 ( Papio anubis ) 的两个 3-4 代核心家族（总共 29 只个体）进行了重新测序，它们的平均繁殖年龄约为 10 岁，并与三个 3 代人类平行分析了数据。血统（26个人）。我们估计狒狒每代的突变率为每个碱基对 0.57×10 ^-8 ，大约是人类的一半。然而，引人注目的是，种系突变的雄性偏好程度约为 4:1，与人类相似——事实上，在出生后数月、数年或数十年繁殖的哺乳动物中也发现了类似的雄性偏好。这些结果反映了人类的发现，即男性突变偏差随着父母年龄的变化而稳定，并进一步质疑生殖系突变跟踪细胞分裂的假设。我们对狒狒突变率的估计提出了一个进一步的谜团，表明猿类和东半球猴之间的分化时间为 6500 万年，这个年龄太老了，与化石记录不一致；现在要协调它们，不仅需要减缓人类每一代的突变率，还需要减缓狒狒的每代突变率。