Little Foot hominin fossil may be new species of human ancestor | Evolution
Little Foot, one of the most complete hominid fossils in the world, could be a new species of human ancestor, according to research that raises questions about our evolutionary past.
Publicly unveiled in 2017, Little Foot is the most complete Australopithecus skeleton never found. The foot bones that give the fossil its name were first discovered in South Africa in 1994, leading to painstaking excavation over 20 years in the Sterkfontein cave system.
Professor Ronald Clarke, a paleoanthropologist at the University of the Witwatersrand, who led the team that excavated the skeleton, attributed Little Foot to the species. Australopithecus Prometheus. Others believed it was African Australopithecusa species first described in 1925 and previously found in the same cave system.
Australopithecus – meaning “southern ape” – was a group of hominids that existed in Africa as early as 4.2 million years ago.
But a new study by Australian researchers, published in the American Journal of Biological Anthropology, found that Little Foot’s traits differ from those of both species, raising a third possibility.
“We think this is a formerly unknown and unsampled species of human ancestor,” said Dr Jesse Martin, an assistant professor at La Trobe University in Melbourne, who led the research.
“It doesn’t look like Australopithecus Prometheus …but it also doesn’t look like all African get out of Sterkfontein.
Martin, also a postdoctoral researcher at the University of Cambridge, added: “This thing will be part of a hominid lineage, so it’s possible that we have not just a point in our human family tree that we hadn’t discovered before, but an entire branch of that tree.”
Martin said Clarke was “one of the only people to claim that there were two species of hominids in Sterkfontein”, and that he had “proven he was right” in this regard.
“Or [Clarke] and I’m leaving, I would say that’s definitely not the case Prometheus“, he said.
Researchers have identified the main differences that distinguish Little Foot from African Australopithecusincluding a longer nuchal plane – a region at the back of the skull.
“The lower part of the skull is thought to be fairly conserved over the course of human evolution, meaning it doesn’t change that quickly,” Martin said. “If you find differences between things at the base of the skull…those differences are more likely to represent different species, because they just don’t change easily, during evolution. All the differences we found are in that region.
“Finding evidence hidden in plain sight at Sterkfontain of an entirely new species is somehow remarkable and counterintuitive,” Martin added, given “this is the most complete human ancestral fossil ever recorded.”
“We should be able to figure out where he fits in the human family tree.”
The study authors have not officially reclassified Little Foot, suggesting: “It is more appropriate that a new species be named by the research team who spent more than two decades excavating and analyzing the remarkable Little Foot specimen. We hope they will consider our suggestion in this regard as well-intentioned advice.”
There has also been disagreement among scientists over Little Foot’s age. The fossil skeleton has been dated to 3.67 million years old, but other scientists have suggested that Little Foot could not be more than 2.8 million years old.
Professor Ronald Clarke, who discovered the skeleton, has been contacted for comment.
