Published: Sun, July 08, 2018
Science | By Joan Schultz

Foot Fossil of Juvenile Hominin Exhibits Ape-Like Features

Foot Fossil of Juvenile Hominin Exhibits Ape-Like Features

A rare juvenile foot fossil of our early hominin ancestor, Australopithecus afarensis, exhibits several ape-like foot characteristics that could have aided in foot grasping for climbing trees, a new study shows.

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Her almost complete skeleton was discovered in the Dikika region of Ethiopia in 2002 by Zeresenay Alemseged, paleontologist and professor of organismal biology and anatomy and the University of Chicago.

"For the first time, we have an fantastic window into what walking was like for a 2½-year-old, more than 3 million years ago", said Jeremy DeSilva, lead study author and an associate professor of anthropology at Dartmouth College, according to CNN. "The Dikika foot adds to the wealth of knowledge on the mosaic nature of hominin skeletal evolution" explains Alemseged.

The most complete foot of an ancient child discovered yet, this tiny clutch of bones no larger than a human thumb has shed light on the mysterious lives of our ancestors.

This is the 3.32 million-year-old Australopithecus afarensis foot from Dikika, Ethiopia, superimposed over a footprint from a human toddler. But Selam actually died more than 100,000 years before Lucy was even alive. But unlike the chimp's big toe, Selam's is in line with her other toes, similar to toes on a human foot.

Without so many amenities in those primitive times, many early humans especially weak toddlers had to climb trees and stay put so that predators remained away from them.

Selam's foot was later discovered in 2002 and is about 2 inches (5.5 centimeters) long - that's a little shorter than a sticky note.

"Every fossil gives us some bit of our past, [but] when you have a child skeleton, you can ask questions about growth and development-and what the life of a kid was like three million years ago", DeSilva told National Geographic.

DeSilva said his research also reveals the toddler would have been quite skilled at walking on two feet, based on the shape of the foot. They found the big toe was more capable of moving side-to-side than skeletons of similar adult feet, meaning it would be better at climbing through branches and latching onto its mother.

Though it has already been established that A. afarensis adults were able to walk on two legs back in the day, not many studies have analyzed the anatomy of their children.

"This foot is very human-like and indicates that the Dikika child was walking on two legs".

This evidence of increased mobility of the toe is an ape-like pattern that DeSilva et al. say is suggestive of a selective advantage of this trait and which offers new insights into the evolution of bipedality.

A 2012 study of Selam's complete shoulder blades also showed them to be apelike because they were adapted for climbing trees.

Scientists started to study one of Selam's foot to find out more about how our ancestors walked.

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