Age at lower first molar (M₁) emergence is a commonly used proxy for inferring life-history scheduling in fossil primates, but its utility is dependent on knowing to what extent extant populations vary in this datum and how this variation correlates with the scheduling of life-history variables. Here, we address the first of these issues among extant chimpanzees. While age at M₁ emergence has been documented in several live individuals from the Kanyawara population of Pan troglodytes schweinfurthii in Uganda, it has been estimated for only one individual of Pan troglodytes verus, based on a deceased animal from the Taï Forest in Côte d’Ivoire. To further explore interpopulation variation in this variable in chimpanzees, and using dental histology, we calculated ages at death for two wild-shot individuals of P. t. verus with erupting M₁, both collected in Liberia during the mid-1950s, and estimated ages at M₁ emergence from the ages at death. The overall range for these two individuals is ∼4.2–4.6 yr, compared with an age of ∼3.7 yr for the individual from the Taï Forest, and <2.5–3.3 yr for the several individuals of P. t. schweinfurthii. While the absolute range of ∼2 yr in these samples combined is little greater than in captive chimpanzees, the disparity between the samples of P. t. schweinfurthii and P. t. verus is striking, although it cannot be determined if this disparity represents a subspecies difference or simply population differences expressed in two different subspecies. While life-history data are unavailable for the population to which the Liberian chimpanzees belonged, the difference in M₁ emergence ages between these individuals and those from Kanyawara still suggests caution when attempting even broad life-history inference in fossil apes and hominins based on age at M₁ emergence.

较低的第一磨牙（M ₁）出现的年龄是推断化石灵长类动物的生活史调度的常用代理，但其效用取决于知道该数据中现存种群变化的程度以及该变异与种群的调度有何关系。生活史变量。在这里，我们解决现存黑猩猩中的第一个问题。虽然在乌干达的Kanyawara的Pan troglodytes schweinfurthii的Kanyawara种群中有几名活着的人记录了M ₁出现的年龄，但据估计只有一个人的Pan troglodytes verus基于科特迪瓦Taï森林中的一只死动物。为了进一步探索黑猩猩中该变量的种群间变异，并使用牙齿组织学，我们计算了两个野生的P. t。个体的死亡年龄。M ₁爆发的真相，都是在1950年代中期在利比里亚收集的，估计的M ₁年龄从死亡年龄开始出现。这两个个体的总范围为〜4.2-4.6岁，而来自Taï森林的个体的年龄为〜3.7岁，而P. t的几个个体的年龄为<2.5-3.3岁。施韦因富特伊。虽然这些样本合在一起的〜2年绝对绝对范围比圈养黑猩猩要大一些，但点 schweinfurthii和P. t。VERUS是惊人的，但是如果该视差表示亚种差或在两个不同的亚种简单地表示人口差异它不能被确定。尽管无法获得利比里亚黑猩猩所属人群的生活史数据，但这些人与来自Kanyawara的人之间的M ₁出现年龄之间的差异仍建议在尝试根据年龄对化石猿猴和人类激素进行更广泛的生活史推断时要谨慎在M ₁出现时。