Bipedal A. Afarensis Lucy

On their own 2 feet: 3.2 million-year-old fossil foot bone supports humanlike bipedalism in Lucy’s species

February 10, 2011 This image shows the position of the fourth metatarsal Australopithecus afarensis (AL 333-160) recovered from Hadar, Ethiopia, in a foot skeleton. Credit: Carol Ward/University of Missouri A fossilized foot bone recovered from Hadar, Ethiopia, shows that by 3.2 million years ago human ancestors walked bipedally with a modern human-like foot, a report that appears Feb. 11 in the journal Science, concludes. The fossil, a fourth metatarsal, or midfoot bone, indicates that a permanently arched foot was present in the species Australopithecus afarensis, according to the report authors, Carol Ward of the University of Missouri, together with William Kimbel and Donald Johanson, of Arizona State University’s Institute of Human Origins.

The research helps resolve a long-standing debate between paleoanthropologists who think A. afarensis walked essentially as modern humans do and those who think this species practiced a form of locomotion intermediate between the quadrupedal tree-climbing of chimpanzees and human terrestrial . The question of whether A. afarensis had fully developed pedal, or foot, arches has been part of this debate. The fourth metatarsal described in the Science report provides strong evidence for the arches and, the authors argue, support a modern-human style of locomotion for this species. The specimen was recovered from the Hadar locality 333, popularly known as the “First Family Site,” the richest source of A. afarensis fossils in eastern Africa, with more than 250 specimens, representing at least 17 individuals, so far known.”This fourth metatarsal is the only one known of A. afarensis and is a key piece of evidence for the early evolution of the uniquely human way of walking,” says Kimbel. “The ongoing work at Hadar is producing rare parts of the skeleton that are absolutely critical for understanding how our species evolved.” Humans, uniquely among primates, have two arches in their feet, longitudinal and transverse, which are composed of the midfoot bones and supported by muscles in the sole of the foot. During bipedal locomotion, these arches perform two critical functions: leverage when the foot pushes off the ground and shock absorption when the sole of the foot meets the ground at the completion of the stride. Ape feet lack permanent arches, are more flexible than human feet and have a highly mobile large toe, important attributes for climbing and grasping in the trees. None of these apelike features are present in the foot of A. afarensis.

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About carlos

I'm a curious person, of reasonable intellect, "on the beach" (retired) and enjoying my interest in anthropology, language, civil rights, and a few other areas. I've been a hippie/student/aerospace tech writer in the '60s, a witness to the Portuguese revolution in the ‘70s, a defense test engineer and witness to the Guatemalan genocide in the '80s, and a network engineer for an ISP in the '90s. Now I’m a student and commentator until my time is up. I've spent time under the spell of the Mesoamerican pyramids and the sweet sound of the Portuguese language. I've lived in Europe, traveled in Brazil, Central America, Iceland, New Zealand, and other places. My preferred mode of travel is with a backpack and I eat (almost) anything local. Somehow, many of the countries I have been to have had civil unrest (for which I was not responsible). I'm open to correspond with anyone who might share my liberal, humanist interests. I live in San Buenaventura, California.
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