Get ready for a fascinating journey into the world of ancient human relatives! The mystery of the Burtele foot has finally been unraveled, revealing a surprising story that challenges our understanding of human evolution.
Scientists have identified the owner of this enigmatic foot fossil, and it's not who you might expect. The bones, dating back 3.4 million years, belonged to a species called Australopithecus deyiremeda, a contemporary of the famous Lucy. But here's where it gets controversial: this discovery could shake up our entire family tree!
The Burtele Foot Mystery Solved
In 2009, a team led by paleoanthropologist Yohannes Haile-Selassie discovered eight foot bones in Ethiopia's Afar region. These bones, along with a jawbone and teeth, were initially a puzzle. The foot had an opposable toe, suggesting a skilled tree climber, but it wasn't enough to name a new species.
However, Haile-Selassie's team didn't stop there. They found more fossil fragments, dating from 3.33 to 3.59 million years ago, and in 2015, they announced a new species: Australopithecus deyiremeda. This announcement sparked debate among experts, given the limited fossil evidence.
The latest study, published in Nature, provides more evidence for this species and includes the Burtele foot bones. It's a game-changer, suggesting that Lucy wasn't the only hominin around 3.8 to 3 million years ago.
A Complex Family Tree
The study reveals that A. deyiremeda walked on two legs, but with a unique twist: it pushed off with its second digit, not its big toe, like modern humans. This diversity in walking styles among early human ancestors is a fascinating insight. "There were many ways of walking on two legs," Haile-Selassie explains, adding that "there was not just one way until later."
By analyzing the chemical signatures in the teeth, the team also discovered that A. deyiremeda had a diet mainly consisting of trees and shrubs, while Lucy had a more varied diet, including grass-based plants. This difference in diet suggests these species coexisted without competing for resources.
Challenging Lucy's Legacy
Fred Spoor, a research leader at the Centre for Human Evolution Research, believes this study will lead to broader acceptance of A. deyiremeda as a genuine species. He suggests that fitting this species into the evolutionary tree may even cause Lucy to lose her "iconic status" as the ancestor of all later hominins, including Homo sapiens.
Lucy, with her apelike face and small brain, was thought to be the sole common ancestor of all later hominins. But recent discoveries of older, upright-walking hominins challenge this view. The new research suggests that our genus, Homo, might not have descended directly from Lucy's species.
When comparing A. deyiremeda to other Australopithecus species, some features, especially its foot and jaw, resemble Australopithecus africanus, a species thought to have descended from Lucy. Other features, like its diet, are similar to Australopithecus anamensis, a more primitive species.
This leads to the intriguing possibility that A. deyiremeda descended from A. anamensis, which would mean Lucy's species, A. afarensis, might not be the ancestor of all later human species. It's a finding that "will cause quite a stir," according to Spoor.
Redrawing the Family Tree
The study suggests a new family tree: A. anamensis at the base, giving rise to at least three sister species (A. afarensis, A. deyiremeda, and A. africanus). This challenges the previous linear descent from A. anamensis to Lucy's species and onwards. With multiple species, it's unclear which gave rise to later hominins.
Ryan McRae, a paleoanthropologist, says this study is the first to suggest Lucy's species might be an evolutionary dead end, not directly ancestral to modern humans. He emphasizes that more evidence is needed to conclude which species, deyiremeda or afarensis, is the ancestor. Regardless, our family tree is becoming increasingly complex.
Haile-Selassie plans to continue his search for more Australopithecus fossils, which will help unravel the relationships between these species. "We need more fossils of A. deyiremeda and A. anamensis to answer the questions we still have about them," he says.
This discovery is a reminder that our understanding of human evolution is constantly evolving. It's a story filled with twists and turns, and we're only beginning to uncover the full picture.
