Phalangeal curvature in chimpanzees and hominins

A study examines phalangeal curvature in the skeletal remains of a chimpanzee raised like a human. Extant arboreal primates and ancient fossil hominins exhibit pronounced curvature of the hand and foot phalanges. However, it is unclear whether the pronounced curvature develops throughout life in response to mechanical loads experienced by hands and feet. Ian Wallace and colleagues examined the skeletal remains of a female chimpanzee that was raised to live like a human during the 1930s in New York City. During its lifetime, the chimpanzee remained mostly indoors with restricted opportunities to engage in arboreal activities. The chimpanzee was trained to walk on two feet, sit in chairs, drink from cups, eat with cutlery, and sleep on a mattress bed with blankets. Despite the lack of arboreal locomotion during the chimpanzee’s lifetime, the degree of phalangeal curvature in its hands and feet was similar to that of wild chimpanzees but not to that of humans. The findings suggest that genetic factors rather than lifetime mechanical loading are the main drivers of phalangeal curvature in chimpanzees and likely other extant arboreal primates and fossil hominins, according to the authors.

ARTICLE #20-04371: “Phalangeal curvature in a chimpanzee raised like a human: Implications for inferring arboreality in fossil hominins,” by Ian J. Wallace, M. Loring Burgess, and Biren A. Patel.

MEDIA CONTACT: Ian J. Wallace, University of New Mexico, Albuquerque, NM; tel: 631-456-8265; email:

[email protected]

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[email protected]

; Biren A. Patel, University of Southern California, Los Angeles, CA; tel: 631-987-2526; email:

[email protected]

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