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

垂直攀爬是现存古猿和猿类经常进行的一种行为，在古猿和人猿的运动进化理论中占有重要地位。例如，有人提出直立爬行的预适应人类是两足行走的。然而，究竟上新世古人类还是中新世古人类会进行垂直攀爬仍然是一个有争议的话题。在乌干达基巴莱国家公园对野生黑猩猩进行的运动学研究表明，垂直攀爬需要极端的足背屈，加上足内翻和外展。因此，我们假设，在垂直攀爬的东半球类人猿中，踝关节或距骨关节的形态是：(1)适应极端背屈、内翻和外展的位置，(2)适应承受在这些足位加载时关节所承受的力。该项目将检查包括人类在内的13种现存灵长类动物脚踝的外部和内部形态，以测试垂直攀登者是否具有独特的距骨关节形态。使用胫骨和距骨的线性和角度特性来评估距骨关节的外部形态。此外，踝关节的复杂形状将使用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附着物的具体位置和形状来确定。最后，将使用现代类人猿tali的CT扫描来检查距骨的内部形态。为了解决已灭绝的人猿和古人类是否在其运动技能中包括垂直攀爬，从现代脚踝研究中获得的结果将应用于胫骨和tali化石，包括从南非化石地点的7个人猿tali中获得的CT扫描数据。该项目研究了大量现代灵长类动物的踝关节，以帮助重建已灭绝的类人猿和人类的运动，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，以测试现代猿类卓越的爬树能力是否有深厚的历史，以及垂直爬树是否可能是人类两足行走的先驱。由于现代人的踝关节经常受伤，本研究还将利用胫骨和tali化石来追踪踝关节韧带的进化史，以确定导致我们现代踝关节解剖结构的时间和环境。

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.