Doctoral Dissertation Improvement: Vertical Climbing Adaptations in the Talocrural Joint of Hominoids and Hominins

垂直攀爬是现存人科动物和远人科动物经常进行的一种行为，在人科动物和古人类的运动进化理论中占有重要地位。例如，有人提出，直立攀爬预先适应了人类的两足行走。 然而，究竟上新世的人类还是中新世的类人，是否有垂直攀爬的习惯，仍是一个有争议的话题。对乌干达基巴莱国家公园野生黑猩猩的运动学研究表明，垂直攀爬需要极端的足背屈，再加上足内翻和外展。因此，我们假设，在垂直攀爬的旧大陆类人猿中，踝关节或距小腿关节的形态（1）适合于极端背屈、内翻和外展的位置，（2）适合于承受在这些足部位置加载时关节上产生的力。该项目将检查包括人类在内的13种灵长类动物踝关节的外部和内部形态，以测试垂直攀登者是否具有独特的距小腿关节形态。将使用胫骨和距骨的线性和角度特性评估距小腿关节的外部形态。此外，脚踝的复杂形状将使用从3D激光扫描获得的数据进行建模。踝关节韧带在限制关节运动和稳定踝关节中的作用将通过量化骨性附件的具体位置和形状来确定。最后，将使用现代距骨的CT扫描检查距骨的内部形态。为了解决灭绝的人科动物和人类是否在其运动技能中包括垂直攀爬，现代踝关节研究的结果将应用于化石胫骨和距骨，包括从南非化石地点获得的七个人类距骨的CT扫描数据。该项目检查了广泛的现代灵长类动物的踝关节，以帮助重建灭绝的猿和人类的运动，并测试早期人类祖先是否有能力爬树。该项目特别关注踝关节，以测试现代猿类非凡的爬树能力是否有很深的历史，以及垂直爬树是否可能是人类两足行走的前兆。由于踝关节在现代人类中经常受伤，这项研究还将使用化石胫骨和距骨追踪踝关节韧带的进化历史，以确定导致我们现代踝关节解剖的时间和环境。

Vertical climbing, a behavior frequently performed by extant hominoids and atelines, has figured prominently in theories of locomotor evolution in the hominoids and hominins. For example, it has been proposed that vertical climbing pre-adapted hominins for bipedality. However, whether Pliocene hominins or Miocene hominoids practiced vertical climbing is still a subject of debate. Kinematic work on wild chimpanzees in Kibale National Park, Uganda has shown that vertical climbing requires extreme foot dorsiflexion, coupled with foot inversion and abduction. It is thus hypothesized that the morphology of the ankle, or talocrural joint, in vertical climbing Old World anthropoids is (1) adapted for positions of extreme dorsiflexion, inversion, and abduction, and (2) adapted to withstand the forces incurred on the joint while being loaded in these foot positions. This project will examine the external and internal morphology of the ankle in thirteen species of living primates, including humans, to test whether vertical climbers have a distinct talocrural joint morphology. External morphology of the talocrural joint will be assessed using linear and angular properties of the tibia and talus. Furthermore, the complex shape of the ankle will be modeled using data obtained from 3D laser scans. The role of ankle ligaments in restricting joint motion and stabilizing the ankle will be determined by quantifying the specific location and shape of the bony attachments. Finally, the internal morphology of the talus will be examined using CT scans of modern anthropoid tali. To address whether extinct hominoids and hominins included vertical climbing in their locomotor repertoire, results obtained from the study of modern ankles will be applied to fossil tibia and tali, including CT scan data obtained from seven hominin tali from fossil localities in South Africa.This project examines the ankle joint across a wide range of modern primates to help reconstruct the locomotion of extinct apes and humans, and test whether early human ancestors were capable tree climbers. This project focuses specifically on the ankle joint to test whether the remarkable tree climbing ability of modern apes has a deep history, and whether vertical tree climbing may have been a precursor to human bipedality. Because the ankle joint is so often injured in modern humans, this study will also track the evolutionary history of ankle ligaments using fossil tibia and tali to determine the timing of and circumstances leading to our modern ankle anatomy.