Scientists have reported the discovered of a 4-million-year-old fossil in Ethiopia that may force us to rethink previous evolutionary theories.
For the first time ever, researchers have revealed the face of the oldest human ancestors that spans back to the very beginning of the human evolutionary tree, after discovered a 3.8-million-year-old skull in Africa.
According to reports, the fossil belongs to an ancient ancestor of humans known as Australopithecus anamensis, believed to be the direct ancestor of the famous “Lucy” species, an ancient hominin dubbed Australopithecus afarensis.
The importance of the discovery resides in the fact that the fossil dates back to a distant time when our early ancestors were in the evolutionary phase leaving trees to walk on two legs.
Despite this crucial feature, the researchers say the species still had distinct ape-like faces, characterized by the pronounced size of their jaws, and smaller brains. The fossil is considered the oldest-known member of the Australopithecus group.
Although the specimen colloquially referred to as Lucy was considered o great importance in the study of human origin and evolution, her ancestors have remained shrouded in mystery, with very few to nearly nonexistent traces on the historical record. In fact, researchers have found only a few bones, and skull fragments, and a few teeth from the species that would give rise to Lucy. These discoveries were not enough to understand the very beginning of a species shrouded in mystery, but which greatly contributed to the evolution of modern humans.
But the latest discovery, an incredible well-preserved adult male skull changed the picture.
The researchers have dubbed the new specimen MRD.
“It is good to finally be able to put a face to the name,” revealed Stephanie Melillo, co-author of one of the analysis, and member of the Max Planck Institute for Evolutionary Anthropology.
The study of the skull-fragments of MRD revealed the hominin had a relatively small brain, at around a quarter of the size of that of a modern human. However, despite the smaller brain, the researchers revealed that MRD was already losing some of its characteristic ape-like features.
Reachsrsa are already celebrating MRD as an icon in the understanding of modern human evolution.
The scientists have revealed that MRDs canines are smaller than those identified in ever earlier fossils, and it shows evidence of the development of a more powerful jaw, and prominent cheekbones as seen in Lucy and other fossils such as the Mrs. Ples Fossil, another member of the Australopithecus group. This evolutionary feature, a more powerful jaw, is what helped the hominin chew through food during drier seasons when less vegetation was available to them.
“MRD lived near a large lake in a region that was dry,” Naomi Levin one of the co-authors of the study revealed in a statement.
“We’re eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change and how it affected human evolution, if at all,” Levin added.
A really ancient species
Scientists have revealed that dating of the skull had proven that Anamensis and its evolutionary descendants, Lucy, coexisted for at least 100,000 years.
This incredible feature is what challenges long-held notions of linear evolution, where one species immediately disappears as it is replaced by a newer one.
However, the recent discovery changes that notion.
The newly found skull proves that the species existed form 4.2 to 3.8 million years ago, and despite being Lucy’s direct ancestor, the hominin prevailed after Lucy had split off from their lineage.
This feature may have been aided by the landscape on Earth, which scientists say was predominant with steep hills, numerous volcanoes, lava flows as well as rifts which may have contributed in isolating populations, eventually helping them diverge.
Nonetheless, these groups are thought to have crossed paths later in time and most likely competed for both food supply and territory.
“This is a game-changer in our understanding of human evolution during the Pliocene,” lead author Yohannes Haile-Selassie announced in a statement.
Rise of Homo sapiens
Scientists have maintained for a long time that Afarensis, which remained present in the fossil record until around 3 million years ago, has often been presented as the likely candidate that eventually gave rise to the Homo lineage. But the new discovery changes everything we thought we know about the evolution of ancient humans, suggesting that a number of diverse lineages co-existed millions of years ago, casting doubt on previously established theories.
“Having multiple candidate ancestral species in the right time and place makes it more challenging to determine which gave rise to Homo,” said co-author of the study Melillo.
Undoubtedly the MRDs skull is set to become an extremely important piece in understanding the evolution and origin of modern humans.