3.4 million-year-old mystery foot assigned to enigmatic human relative that lived alongside Lucy
A mysterious fossilized foot discovered years ago in Ethiopia belongs to a controversial and enigmatic human relative who lived around the same time as our ancestor. »Lucy“, reveals a new study.
This discovery lasted for years. In 2009, scientists discovered a 3.4 million-year-old fossil foot with toes designed for life in trees. Today, newly discovered fossilized teeth and jaw bones have been discovered near the so-called “Burtele’s foot” suggest that members of Lucy’s species, Australopithecus afarensislived side by side with another now-extinct human relative, Australopithecus deyiremedawhich lived approximately 3.5 million to 3.3 million years ago.
But like Lucy, At. deyiremeda walked on two legs when on the ground, showing that different hominids living at the same time moved very differently from each other.
“What we’re learning now is that, yes, bipedalism was a key part of our evolutionary history, but there were so many ways to walk on two legs on the ground,” says the study’s first author. Yohannès Hailé-Sélassiépaleoanthropologist and director of the Institute of Human Origins at Arizona State University, told Live Science.
He said there were “many experiments on bipedalism”, with different elements of the foot, pelvis and leg bones evolving at different rates and at different times.
Before the discovery of Burtele’s foot, hominids were thought to be completely bipedal during Lucy’s time, as she had one big toe in line with the other four digits. But Burtele’s foot, which belonged to an adult, has long, curved toes used to grip tree branches.
Researchers also discovered a jaw with teeth at the same site in Ethiopia. However, they were unsure if these remains were the same species as Burtele’s foot, as they were unsure if they were from the same time period.
In 2015, the species At. deyiremeda was appointed based on this jaw and others; However, this new species was controversial because the shape and size of the teeth are similar to those of Lucy and an older hominid, Australopithecus anamensis.
Meanwhile, the species of Burtele’s foot remained unknown for years because the head bones are necessary for species designation, Haile-Selassie said. So he and his team returned to Woranso-Millé site in the Afar region to search for more fossil remains.
Researchers found 13 new fossil tooth and jaw fragments of the same age near where Burtele’s foot was discovered. Compared to dental remains of other hominid species, these have been “confidently” attributed to At. deyiremedathe researchers wrote in the new study. Based on their similar age and location, the team believes the teeth and foot belonged to members of the same species.
A chemical analysis of tooth enamel revealed that although Lucy’s species and At. deyiremeda took up residence in Woranso-Mille, they did not need to fight for resources. At. deyiremeda lived in a wooded environment and fed mainly on trees and shrubs, while At. afarensis had a varied diet and lived in more open habitats.
“I think that dietary differences and differences in locomotor adaptation would be the best way to coexist,” Hailé-Sélassié said. “Is this a surprise? Maybe not, because we know that today modern primates – closely related primates – live together in the same area.”
A controversial coexistence
The reaction to Burtele’s foot belonging to At. deyiremeda was mixed.
Zeray Alemsegedpaleoanthropologist and professor of organismal biology and anatomy at the University of Chicago who was not involved in the new study, is not convinced that the foot and dental remains belong to the same species. He noted that the association is based on circumstantial evidence, namely their proximity in time and space.
Alemseged told Live Science that if At. deyiremeda is a separate species, it is not clear to him whether it belongs to the genus Australopithecus or if it is a late surviving species of the oldest genus Ardipithecuscurrently known to have lived until approximately 4.4 million years ago.
However, other experts agree that Lucy and her people shared the landscape with this other Australopithecus species. Jeremy DeSilvaa biological anthropologist from Dartmouth College who was not involved in the research, said that At. deyiremeda “is anatomically distinct, but to me what’s much more valuable is how behaviorally distinct it is,” such as being more selective in what it ate and spending more time in trees.
In fact, DeSilva is now converted and believes that A. deyiremeda is a distinct species and the foot belongs to it. “Australopithecus deyiremeda “There was always a question mark next to it for me” since it was first proposed as a species, he told Live Science. “That’s not the case now. That question mark is gone.”
“For me, this document is a ‘welcome to the family tree’ Australopithecus deyiremeda” added DeSilva. “Now we have our hands full trying to figure out, okay, where does this thing fit in?”
