A new study has concluded that adults and their small children were walking upright on two feet over three million years ago after examining the Dikika foot from the skeleton of an Australopithecus afarensis child that lived 3.32 million years ago.
According to Phys.org, the foot that was recovered is the most intact foot from this era that scientists have ever been able to study, as Jeremy DeSilva from Dartmouth College explained.
“For the first time, we have an amazing window into what walking was like for a 2½-year-old, more than 3 million years ago. This is the most complete foot of an ancient juvenile ever discovered.”
The child’s foot is extremely tiny and has been measured as being roughly the same size as an adult’s thumb. The skeleton of the Australopithecus afarensis child was originally found in 2002 in Ethiopia.
Paleontologist Zeresenay (Zeray) Alemseged, from the University of Chicago, is responsible for this discovery and is also the lead author of the newest research. He notes that while this species of human was indeed walking upright, they hadn’t quite reached the level of Homo erectus yet when it came to their movement on two feet.
“Placed at a critical time and the cusp of being human, Australopithecus afarensis was more derived than Ardipithecus (a facultative biped) but not yet an obligate strider like Homo erectus. The Dikika foot adds to the wealth of knowledge on the mosaic nature of hominin skeletal evolution.”
If the name Australopithecus afarensis sounds familiar, it is because this skeleton belongs to the same family as the well-known Lucy fossil. This particular skeleton was also found very close to where Lucy was discovered, which may be part of the reason why the Dikika fossil was originally known as “Lucy’s baby” when it was first found in 2002. However, the newer skeleton is actually much older than Lucy, and this child would have been roaming Africa 200,000 years before Lucy was born.
When scientists examined the Dikika foot, they did it with the intention of trying to understand how this species of human would have lived and survived over 3 million years ago. They scrutinized the foot closely to see exactly how it would have been used and also how a foot like this would have developed over the course of human evolution.
DeSilva notes that early humans were excellent at walking on two legs, but even the use of two legs wouldn’t have helped much if they hadn’t managed to walked correctly as they would have quickly fallen prey to the many predators around them.
“Walking on two legs is a hallmark of being human. But, walking poorly in a landscape full of predators is a recipe for extinction.”
While this small child was indeed found to have been walking upright, scientists were able to determine that she still would have spent at least part of her time moving among trees with her mother, who would have been in search of food for the family.
Interestingly, scientists also found that the child would have actually spent less time walking upright than adults, and more time up in trees. According to DeSilva, this makes perfect sense when you consider that trees would have been much safer places for children 3 million years ago, especially when their parents weren’t present.
“If you were living in Africa 3 million years ago without fire, without structures, and without any means of defense, you’d better be able get up in a tree when the sun goes down.”
The new study on the examination of the Dikika foot which shows that early human Australopithecus afarensis children were walking upright has been published in Science Advances.