Pair of ancient skeletons thought to represent two different human ancestors are actually from the same species, scientists confirm
- Ancient bones of juvenile male and adult female were found at Malapa in 2008
- Were at first thought to be same species but later study suggested they were not
- New research on 135 fossils has now confirmed they’re from the same species
- Researchers say they represent different growth stages in species A. sediba
New research on a pair of two million-year-old skeletons is helping to solidify the timeline of human evolution.
After two partial skeletons were found at a South African site known as the Cradle of Humankind a decade ago, debate arose as to whether they were from the same species, or represented two distinct human ancestors.
Now, a series of studies meticulously analyzing the remains has finally put the issue to rest.
Despite apparent differences in certain bone structures, researchers say the two skeletons are, in fact, from the same species – they simply represent two different stages of growth.
New research on a pair of two million-year-old skeletons is helping to piece together the timeline of human evolution. An analysis of 135 fossils has revealed that the remains are from two individuals of the same species of human ancestor. A reconstruction of A. sediba is shown
Researchers from several universities published a total of nine papers in a special issue of the journal PaleoAnthropology this month investigating the two ancient skeletons.
The bones of the juvenile male (MH1) and adult female (MH2) were found at the fossil site of Malapa back in 2008.
At the time, discoverer Lee Berger and colleagues named a new hominin species based on the find: Australopithecus sediba.
Several years later, however, a research group suggested the two individuals may not be from the same species, due to differences in their lumbar vertebrae.
An exhaustive analysis of 135 fossils has now allowed researchers to outline the body proportions and walking mechanics of the two long-deceased human ancestors, along with their skull, vertebral column, and other parts.
After two partial skeletons were found at a South African site known as the Cradle of Humankind a decade ago, debate arose as to whether they were from the same species, or represented two distinct human ancestors
And, they say these two individuals were both of the species A. sediba.
‘Our interpretations in the paper suggest that A. sediba was adapted to terrestrial bipedalism, but also spent significant time climbing in trees, perhaps for foraging and protection from predators,’ says NYU anthropologist Scott Williams, who focused on the axial skeleton – or, the vertebrae, ribs, and sternum.
‘This larger picture sheds light on the lifeways of A. sediba and also on a major transition in hominin evolution, that of the largely ape-like species included broadly in the genus Australopithecus to the earliest members of our own genus, Homo.’
The bones of the juvenile male (MH1) and adult female (MH2) were found at the fossil site of Malapa back in 2008. At the time, discoverer Lee Berger and colleagues named a new hominin species based on the find: Australopithecus sediba
The bones of the juvenile male (MH1) and adult female (MH2) were found at the fossil site of Malapa back in 2008. The South African site is within a region known as the Cradle of Humankind
WHEN DID HUMAN ANCESTORS FIRST EMERGE?
The timeline of human evolution can be traced back millions of years. Experts estimate that the family tree goes as such:
55 million years ago – First primitive primates evolve
15 million years ago – Hominidae (great apes) evolve from the ancestors of the gibbon
7 million years ago – First gorillas evolve. Later, chimp and human lineages diverge
A recreation of a Neanderthal man is pictured
5.5 million years ago – Ardipithecus, early ‘proto-human’ shares traits with chimps and gorillas
4 million years ago – Ape like early humans, the Australopithecines appeared. They had brains no larger than a chimpanzee’s but other more human like features
3.9-2.9 million years ago – Australoipithecus afarensis lived in Africa.
2.7 million years ago – Paranthropus, lived in woods and had massive jaws for chewing
2.6 million years ago – Hand axes become the first major technological innovation
2.3 million years ago – Homo habilis first thought to have appeared in Africa
1.85 million years ago – First ‘modern’ hand emerges
1.8 million years ago – Homo ergaster begins to appear in fossil record
800,000 years ago – Early humans control fire and create hearths. Brain size increases rapidly
400,000 years ago – Neanderthals first begin to appear and spread across Europe and Asia
300,000 to 200,000 years ago – Homo sapiens – modern humans – appear in Africa
50,000 to 40,000 years ago – Modern humans reach Europe
According to the researchers, the discrepancies noted in the lumbar vertebrae of the two specimens occur because one was an individual and the other was a fully grown adult.
‘The differences in these vertebrae can simply be attributed to their developmental age differences: the juvenile individual’s vertebrae have not yet completed growth, whereas the adult’s vertebra growth is complete,’ Williams said.
‘As it happens, the two Homo erectus skeletons we have are juveniles, so MH1 looks more similar to them because it too is a juvenile.’