Doctoral Dissertation Research: The role of thermoregulation in the obstetrical dilemma

在人类分娩过程中，婴儿与产道非常吻合，人类学家对了解是什么进化压力导致了女性骨盆的大小和形状，从而导致分娩困难感兴趣。该项目将测试体温调节假说，该假说认为，人类骨盆的宽度受到保持身体较窄以保持凉爽的需要的限制。人类祖先在温暖的气候中进化，从事艰苦的活动，而狭窄的身体有助于调节温度。将收集活人骨盆尺寸的骨骼数据和温度调节数据，以解决温度调节假说。这些数据也可用于预测女性难产风险和防止娱乐和专业运动员过热。此外，该项目将为两名来自科学领域代表性不足群体的女本科生提供STEM培训。项目成果将在当地高中和美国自然历史博物馆与公众分享。对于“产科困境”的传统解释，即为什么现代人类女性的产道没有扩大以使分娩更容易，是狭窄的骨盆在两足运动时更有效。然而，热调节假说认为，窄骨盆有助于身体活动时的热调节，这一假说已经作为一种竞争性假说进行了讨论。本研究将探讨体温调节在限制产道进化中的潜在作用。研究人员推测，现代人在进行体力活动时，狭窄的骨盆有助于体温调节，臀部宽度与产道面积有关，直立人是一种体型狭窄、适应热的分类单元。研究人员将收集跑步者的体温调节数据，以确定窄骨盆是否在运动中具有体温调节优势；测量女性骨盆尺寸使用三维扫描创建的生态地理不同的人口；并重建了KNM-WT 15000直立人骨盆，这是有争议的，因为原始重建提供了在智人进化之前具有狭窄骨盆的人族的唯一证据。这些数据将有助于更广泛地理解难产背后的进化原因。

In human childbirth, the baby fits very tightly in the birth canal, and anthropologists are interested in understanding what evolutionary pressures may have led to a female pelvic size and shape that can contribute to difficult childbirth. This project will test the thermoregulation hypothesis, which suggests that the width of the human pelvis is limited by the need to maintain a narrow body that is good at staying cool. Human ancestors evolved in warm climates and engaged in strenuous activities, and a narrow body aids in temperature regulation. Skeletal data on pelvic dimensions and temperature regulation data from living people will be collected to address the thermoregulation hypothesis. These data may also be informative for predicting women at risk of obstructed labor and for preventing overheating in recreational and professional athletes. Additionally, this project will support STEM training for two female undergraduate students from groups underrepresented in science. Project results will be shared in local high schools and with the general public at the American Museum of Natural History.The traditional explanation for the "obstetrical dilemma," which asks why the modern human female birth canal has not expanded to make birth easier, is that a narrow pelvis is more efficient during bipedal locomotion. However, the thermoregulation hypothesis, which suggests that a narrow pelvis aids in thermoregulation during physical activity, has been discussed as a competing hypothesis. This research will investigate the potential role of thermoregulation in constraining the evolution of the birth canal. The investigators hypothesize that a narrow pelvis aids in thermoregulation in modern humans during physical activity, that hip breadth is correlated with the area of the birth canal, and that Homo erectus was a narrow-bodied, heat-adapted taxon. The investigators will collect thermoregulation data from runners to determine if a narrow pelvis bestows thermoregulatory advantages during exercise; measure female pelvic dimensions using three-dimensional scans created from eco-geographically varied populations; and reconstruct the KNM-WT 15000 H. erectus pelvis, which is controversial because the original reconstruction provides the only evidence of a hominin with a narrow pelvis prior to the evolution of Homo sapiens. These data will contribute to a broader understanding of the evolutionary reasons behind obstructed labor.