Ontogeny of Heel-Strike in Hominoids

这个项目将研究行走和足部解剖的一个特殊特征，这可能会为人类两足行走（直立行走）的进化提供新的见解。人类和我们的近亲非洲大猿使用独特的脚撞击模式，在行走时，它们首先用脚跟撞击地面，然后用脚的其他部分（脚跟撞击）。然而，影响特殊脚姿势进化的因素以及我们独特（人类）脚步模式的首次出现仍然知之甚少。目前尚不清楚人类和非洲猿类的脚跟着地在多大程度上相似，它在个体一生中如何发展，以及不同的脚跟着地模式如何反映在脚骨的解剖结构中。这项研究追踪了非洲猿脚姿势的发展，并提供了一个独特的机会来了解为什么非洲猿和人类的脚跟罢工，并探索化石人类的脚骨如何告诉我们人类进化过程中的行走模式。该项目将支持一名早期职业女性科学家，并为研究生和本科生提供大量研究机会，特别关注女性和少数民族学生。在项目结束时，所有视频和图像数据将提供给其他科学家和教育工作者，并用于促进公共动物学设施和保护区的研究和教育目标。脚跟罢工的信息不仅可以应用于化石记录，但也在human.The项目的目标是量化整个个体发育过程中的非洲古猿脚跟罢工功能形态的研究。该研究将通过实验，比较，个体发育的方法量化使用脚跟撞击的活体灵长类动物中踏板力学和解剖学的变化范围，并提出：（1）脚跟撞击的力学在所有发生的情况下都是一样的吗？(2)身体尺寸、行为、年龄和后肢动力学如何影响脚跟撞击力学？（3）足跟撞击能否在跟骨内外部解剖结构中检测到？要测试假设后肢力学脚跟罢工的影响，运动学数据进行了分析，从非侵入性的视频记录的婴儿和成年黑猩猩和大猩猩行走。为了研究足内翻和相关的地面反作用力如何在运动发育过程中加载跟骨的变化，用安装在力平台顶部的压力垫记录由足引起的压力中心和地面反作用力。这些数据与以前收集的野生黑猩猩的视频数据进行了比较。磁共振成像（MRI）和医学计算机断层扫描（CT）被用来模拟非洲猿脚跟垫如何在没有跟骨外侧足底突的情况下衰减冲击力。这些数据与圈养和野生现存猿类和人类跟骨小梁结构的microCT数据进行了比较，然后应用于早期化石人类跟骨（A。afarensis和A. sediba）。这个综合项目是变革性的，因为它调查了整个功能链：运动行为和步态力学（运动学，动力学和足底压力）在整个个体发育，内部和外部跟骨结构在现存的猿类，和化石脚骨功能形态的解释。全面了解现生猿类的足跟撞击变异及其在化石人类中的进化，是更广泛地了解人科动物足跟撞击进化的重要第一步。

This project will study a particular feature of walking and foot anatomy that may provide new insight about the evolution of bipedalism (walking upright) in humans. Humans and our closest living relatives, the African great apes, use a unique foot strike pattern in which they strike the ground with the heel first, before the rest of the foot (heel strike) when walking. Yet the factors influencing the evolution of a specialized foot posture and the first appearance of our unique (human) footfall patterns are still poorly understood. It is unknown to what degree heel strike is similar across humans and African apes, how it develops throughout an individual's lifetime, and how different patterns of heel strike are reflected in the anatomy of foot bones. This study tracks the development of foot posture in African apes and provides a unique opportunity to understand why African apes and humans heel strike, and to explore how fossil hominin foot bones might tell us about walking patterns during hominin evolution. This project will support an early career female scientist and provide numerous research opportunities for graduate and undergraduate students, with a specific focus on female and minority students. At the end of the project, all video and image data will be made available to other scientists and educators, and used to promote the research and education goals of public zoological facilities and sanctuaries. Information on heel strike can be applied not only to the fossil record but also to studies of foot development and injuries in humans.The objective of this project is to quantify patterns of heel strike functional morphology throughout ontogeny in African hominoids. The study will quantify the range of variation in pedal mechanics and anatomy among living primates who use a heel strike through an experimental, comparative, ontogenetic approach, and ask: (1) are the mechanics of heel strike the same in all contexts in which it occurs?, (2) how do body size, behavior, age, and hind limb dynamics influence heel strike mechanics?, and (3) can heel strike be detected in external and internal calcaneal anatomy? To test hypotheses regarding the effect of hind limb mechanics on heel strike, kinematic data are analyzed from non-invasive video recordings of infant and adult chimpanzees and gorillas walking. To investigate how foot inversion and associated ground reaction forces that load the calcaneus change during locomotor development, the center of pressure and ground reaction forces incurred by the foot are recorded with a pressure mat mounted on top of a force platform. These data are compared with previously collected video data of wild chimpanzees. Magnetic resonance imaging (MRI) and medical computed tomography (CT) are used to model how the African ape heel pad attenuates impact forces in the absence of a calcaneal lateral plantar process. These data are compared with microCT data of calcaneal trabecular architecture in captive and wild extant apes and humans and then applied to early fossil hominin calcanei (A. afarensis, and A. sediba). This integrative project is transformative because it investigates an entire functional chain: locomotor behavior and gait mechanics (kinematics, kinetics, and plantar pressure) throughout ontogeny, internal and external calcaneal structure in extant apes, and interpretation of fossil foot bone functional morphology. A comprehensive understanding of heel strike variation in living apes and its evolution in fossil hominins is an essential first step toward a broader understanding of the evolution of heel strike in hominoids.