Doctoral Dissertation Research: Obstetric constraints on neurocranial shape in nonhuman primates

“产科困境”指的是人类婴儿的头部和母亲的产道之间的紧密配合，这是一种导致分娩困难和产妇死亡的不相称。然而，人类并不是唯一经历产科困难的灵长类动物。在一些体型较小的猴子物种中，有记录显示，分娩并发症严重到产妇或婴儿死亡，这些猴子的婴儿在出生时身体相对较大。本博士论文的研究测试的假设，婴儿颅骨狭窄是一种进化适应，以减轻产科约束，在这些小身体的猴子。通过加深我们对非人类灵长类的产科约束的理解，以及这些物种如何应对它，我们也可以更好地理解人类产科困境的进化根源。该项目支持研究和培训一名职业初期的女科学家，并开发关于产科限制因素的演变以及产科和生殖保健必要性的教育模块。许多新世界的小型猴都有着狭长的头骨形状，与人类和猿类的球状形成对比。先前的研究表明，颅骨狭窄使这些物种能够生下大脑婴儿，同时最大限度地减少难产的风险，这与人类产科困境相似。相反，体型较小的旧大陆猴在成年后不会表现出颅骨狭窄，这种差异可以通过产科限制的变化或出生后颅骨形状变化的物种间差异来解释。该项目分析了非人类灵长类动物中产科约束和颅骨狭窄之间的相关性，并使用几何形态测量学来跟踪具有代表性的小型新世界猴和旧世界猴从婴儿到成年生命阶段的颅骨形状变化。研究人员综合了产科和发育形态学领域先前研究的方法，创建了灵长类动物产道的3D重建，并生成了对未来人类学研究有价值的灵长类动物婴儿CT扫描数据。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The “obstetric dilemma” refers to the tight fit between a human infant’s head and its mother’s birth canal, a disproportion that contributes to difficult labor and maternal mortality. However, humans are not the only primates to experience obstetric difficulties. Birth complications as severe as maternal or infant death have been recorded in some small-bodied monkey species, whose babies have relatively large bodies during birth. This doctoral dissertation research tests the hypothesis that infant cranial narrowness is an evolutionary adaptation to mitigate obstetric constraint in these small-bodied monkeys. By deepening our understanding of obstetric constraint in nonhuman primates, and how these species cope with it, we may also better understand the evolutionary roots of the human obstetric dilemma. This project supports the research and training of an early-career female scientist and development of educational modules on the evolution of obstetric constraint and the necessity of obstetric and reproductive healthcare. Many small-bodied new-world monkeys exhibit a long and narrow skull shape, in contrast to the globular shape observed in humans and apes. Previous research suggests that cranial narrowness allows these species to give birth to large-brained infants while minimizing the risk of obstructed labor, drawing parallels to the human obstetric dilemma. Conversely, small-bodied old-world monkeys do not exhibit cranial narrowness as adults, a disparity that could be explained by variation in obstetric constraints or by interspecies differences in how cranial shape changes after birth. This project analyzes the correlation between obstetric constraint and cranial narrowness in nonhuman primates and uses geometric morphometrics to track cranial shape change from infant to adult life stages in representative species of small-bodied new-world and old-world monkeys. The investigators synthesize methods from prior research in the fields of obstetrics and developmental morphology to create 3D reconstructions of the primate birth canal and generate infant primate CT scan data valuable to future anthropological research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.