3 Million Years Ago, Toddlers Could Walk Upright and Climb Trees


Scientists have reanalyzed fossils of a three-million-year-old toddler of an early hominid species called Australopithecus afarensis. They realized that the children could walk on two feet and climb trees. The discovery is critical in discovering hominid evolution.

The fossilized foot is as small as a human thumb. Its physical appearance shows the capacities of A. afarensis and their behavior wrote the authors of the research in Science Advances on 4 July.

It has been for a while since scientists were aware that the early ape-like hominid A. afarensis was part of our family tree, and walked on two feet. But the new paper wrote by lead author Jeremy DeSilva (Dartmouth College) suggests that children could stand, walk upright and even climb trees. This attribute could have allowed them to cling to their mothers, climb trees and outsmart predators.

The Dikika Child

In 2002, the co-author of this study, Zeresenay Alemseged, who is also a professor of organismal biology and anatomy at the University of Chicago, found the fossilized remains of an infant. It was a female child of almost two-and-a-half years old. She was found in the Dikika region of Ethiopia. The professor found a skull, almost a complete vertebral column with ribs, shoulder bones, part of her arms and legs and the foot.

This is the most complete foot of an ancient child uncovered until now, said DeSilva:

“Most of the fossil record consists of adults—it is unusual to find fossilized remains of children, and these give us wonderful insight into growth and development in our ancestors.”

The fossil was identified as belonging to the same species as the Lucy fossil and is 3.32 million years old. Since the 2006 analysis, the bones have been exposed and cleared of sediment, revealing more information.

The Dikika child’s foot shows that the toddler already had the bone structure needed to stand and walk. However, the foot also has characteristics found in apes – allowing the child to cling to her mother or to climb trees, explains DeSilva:

“This foot is very human-like and indicates that the Dikika child was walking on two legs. However, the bone at the base of our big toe—called the medial cuneiform—has a connection for the big toe that is more curved and slightly more angled than what is found in humans today. Such a curved surface would allow motion of that big toe—which modern apes use for grasping. We conclude from this, and from previous studies on the shoulders of the Dikika child that she would have been able to climb, and to also grasp onto her mother during travel.”

Better Climbers than Their Parents

Researchers conclude that the children of A. afarensis might have had better climbing abilities than their parents and that they spent more time in trees, said DeSilva:

“They were smaller, probably more playful, and also had to scurry up into the trees to get away from predators more frequently than the adults did. We think that this helps explain the differences we see between the bones of the Dikika toddler and the more human-like bones of the adults.”


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