New discovery changes perceptions of human evolution

Fossil discovery proves hominids walked earlier than thought.

A study published last week in the journal Science revealed humans developed arched feet much earlier than scientists thought —- a discovery that is shaking up the way evolution is viewed in the science world.

The study, conducted by MU researcher Carol Ward along with William Kimbel and Donald Johanson of Arizona State University, provides evidence that humans’ ancestors were walking upright in the time of the famous 3.2 million year old Ethiopian skeleton named Lucy. The fourth metatarsal of Australopithecus afarensis shows this species was more similar to humans than previously thought.

“Now that we know Lucy and her relatives had arches in their feet, this affects much of what we know about them, from where they lived to what they ate and how they avoided predators,” Ward said. “The development of arched feet was a fundamental shift toward the human condition, because it meant giving up the ability to use the big toe for grasping branches, signaling that our ancestors had finally abandoned life in the trees in favor of life on the ground.”

This finding proves this species, which many think of as the evolutionary link between humans and apes, was walking on two legs like humans, rather than swinging from trees like monkeys. The Australopithecus had strong jaws that allowed it to eat several types of food, which combined with its skill of walking, allowed it to scavenge for food and roam areas outside of the forest.

Ward said from these evolutionary discoveries, researchers have the opportunity to learn more about the human species’ current condition.

“Arches in the feet are a key component of human-like walking because they absorb shock and also provide a stiff platform so that we can push off from our feet and move forward,” Ward said. “People today with ‘flat feet’ who lack arches have a host of joint problems throughout their skeletons. Understanding that the arch appeared very early in our evolution shows that the unique structure of our feet is fundamental to human locomotion.

Ward said if people can understand what humans were designed to do and the natural selection that shaped the human skeleton, people could gain insight into how human skeletons work today.

Having arched feet sets Australopithecus afarensis apart its predecessors like Ardipithecus ramidu, which moved on all four powerful feet, which equipped the hominid for grasping branches and climbing trees.

“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,” Kimbel, who is continuing his research in Ethiopia, said. “The ongoing work at Hadar is producing rare parts of the skeleton that are absolutely critical for understanding how our species evolved.”

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