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Bipedality, the ability to walk upright on two legs, is a hallmark of human evolution. Many primates can stand up and walk around for short periods of time, but only humans use this posture for their primary mode of locomotion.
Fossils suggests that bipedality may have begun as early as
6 million years ago. But it was with
Australopithecus,
an early hominin who evolved in southern and eastern Africa between 4 and 2 million years ago, that our ancestors took their first steps as committed bipeds. Yet scientists still know little about the circumstances that led to this trait's emergence.Carol Ward, a paleoanthropologist and anatomist at the University of Missouri, studies this question. A specialist in human origins, Ward has spent a number of field seasons at various paleontological sites, including at Kanapoi and Lomekwi in West Turkana, Kenya, where she and her colleagues recovered
australopithecine fossils. Her latest work repurposes 3D medical-imaging technologies to compare modern primate anatomy, including soft tissues and organs, with the skeletal fossil record of ancient hominids. That technique allows her to make inferences about our ancient ancestors and how their bodies supported different forms of locomotion. As she discussed in a short lecture at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, D.C., in February, figuring out how and why humans became bipedal could be essential to understanding human evolution more broadly.
The following conversation with Ward has been edited for clarity and brevity.
Comment: While China may be suffering the worst of plummeting insect numbers, its a similar story throughout much of the 'civilized' world. It's also worth noting that not every decline in insect species has been directly correlated with loss of habitat or excessive use of pesticides and herbicides: Nearly 100 species of frogs, toads and salamanders wiped out by fungus
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