“Little Foot” Fossil May Represent Previously Unknown Human Ancestor
A groundbreaking new study suggests the remarkably complete “Little Foot” hominin fossil, discovered in South Africa, may not fit neatly into existing classifications of human ancestors, perhaps representing a previously unknown species.Unveiled to the public in 2017, Little Foot is the most complete Australopithecus skeleton ever found, offering an unprecedented glimpse into our evolutionary past.
The fossil, initially identified by foot bones discovered in 1994, underwent over two decades of meticulous excavation and analysis at the Sterkfontein Caves, a UNESCO World Heritage site known for its rich hominin fossil record. Traditionally, little Foot has been associated with either Australopithecus prometheus or Australopithecus africanus, two species of hominins that inhabited Africa as early as 4.2 million years ago.
[Image of students visiting Sterkfontein where Little Foot was discovered. Photograph: La Trobe University]
However, research published in the American Journal of Biological Anthropology by a team of Australian scientists challenges these existing classifications. The study indicates that Little Foot possesses unique traits that distinguish it from both A. prometheus and A. africanus, leading researchers to propose a third possibility.
“We think it is indeed a formerly unknown, unsampled species of human ancestor,” explained a lead researcher from La Trobe University in Melbourne. “It doesn’t look like Australopithecus prometheus… but it also doesn’t look like all of the africanus to come out of Sterkfontein.”
The implications of this finding are important.According to a postdoctoral research fellow at the University of Cambridge involved in the study, Little Foot could represent not just a new point on the human family tree, but “an entire limb of that tree.” This suggests a more complex and diverse evolutionary history than previously understood.
The research team’s findings corroborate the long-held belief of Professor Ronald Clarke of the University of the Witwatersrand, who led the original excavation. Clarke was “one of the only people to maintain there were two species of hominin at sterkfontein,” and the new study appears to validate his position. However, the researchers diverge from Clarke’s initial assessment regarding the specific species. “Where [Clarke] and I depart is I would argue one is definitely not prometheus,” the researcher stated.
Key to the new classification is the identification of distinct differences in Little Foot’s anatomy, particularly a longer nuchal plane – the region at the back of the skull.”The bottom back of the skull is supposed to be fairly conserved in human evolution, which is to say it doesn’t change that rapidly,” the researcher explained. “If you find differences between things in the base of the cranium… those differences are more likely to represent different species, as they just don’t change readily, evolutionarily speaking. All of the differences we’ve found are in that region.”
[Image of a map showing the site where Little Foot was discovered. Illustration: La Trobe University]
The finding of these subtle yet significant differences is particularly remarkable given the completeness of the little Foot fossil. “To find evidence hiding in plain sight at Sterkfontein of an entirely new species is kind of remarkable and counterintuitive,” the researcher added, noting that Little Foot is “the most complete human ancestral fossil in the record.”
Despite the compelling evidence, the study’s authors have not formally reclassified Little Foot. They suggest it is more appropriate for the team that has dedicated over two decades to excavating and analyzing the specimen to formally name the new species, expressing hope that their research will be considered “well-intentioned advice.”
Ongoing debate also surrounds the age of the fossil, with estimates ranging from 3.67 million years old to as little as 2.8 million years old. Professor Clarke, the original discoverer of the skeleton, has been contacted for comment on the new findings.
Ultimately, the ongoing investigation into Little Foot promises to reshape our understanding of the complex and branching story of human evolution.
