'First human' discovered in Ethiopia

'First human' discovered in Ethiopia

Scientists have unearthed the jawbone of what they claim is one of the very first humans.

The 2.8 million-year-old specimen is 400,000 years older than researchers thought that our kind first emerged.

The discovery in Ethiopia suggests climate change spurred the transition from tree dweller to upright walker.

The head of the research team told BBC News that the find gives the first insight into "the most important transitions in human evolution".
Prof Brian Villmoare of the University of Nevada in Las Vegas said the discovery makes a clear link between an iconic 3.2 million-year-old hominin (human-like primate) discovered in the same area in 1974, called "Lucy".

Could Lucy's kind - which belonged to the species Australopithecus afarensis -
have evolved into the very first primitive humans?
"That's what we are arguing," said Prof Villmoare.
But the fossil record between the time period when Lucy and her kin were alive
and the emergence of Homo erectus (with its relatively large brain and humanlike
body proportions) two million years ago is sparse.
The 2.8 million-year-old lower jawbone was found in the Ledi-Geraru research
area, Afar Regional State, by Ethiopian student Chalachew Seyoum. He told BBC
News that he was "stunned" when he saw the fossil.
"The moment I found it, I realised that it was important, as this is the time period
represented by few (human) fossils in Eastern Africa."
The fossil is of the left side of the lower jaw, along with five teeth. The back
molar teeth are smaller than those of other hominins living in the area and are
one of the features that distinguish humans from more primitive ancestors,
according to Professor William Kimbel, director of Arizona State University's
Institute of Human Origins.
"Previously, the oldest fossil attributed to the genus Homo was an upper jaw from
Hadar, Ethiopia, dated to 2.35m years ago," he told BBC News.
"So this new discovery pushes the human line back by 400,000 years or so, very
close to its likely (pre-human) ancestor. Its mix of primitive and advanced
features makes the Ledi jaw a good transitional form between (Lucy) and later
humans."
A computer reconstruction of a skull belonging to the species Homo habilis , which
has been published in Nature journal, indicates that it may well have been the
evolutionary descendant of the species announced today.
The researcher involved, Prof Fred Spoor of University College London told BBC
News that, taken together, the new findings had lifted a veil on a key period in the
evolution of our species.
"By discovering a new fossil and re-analysing an old one we have truly contributed
to our knowledge of our own evolutionary period, stretching over a million years
that had been shrouded in mystery," he said.
Climate change
The dating of the jawbone might help answer one of the key questions in human
evolution. What caused some apes to climb down from the trees and make their
homes on the ground.
A separate study in Science hints that a change in climate might have been a
factor. An analysis of the fossilised plant and animal life in the area suggests that
what had once been lush forest had become dry grassland.
As the trees made way for vast plains, apes found a way of exploiting the new
environmental niche, developing bigger brains and becoming less reliant on having
big jaws and teeth by using tools.
Prof Chris Stringer of the Natural History Museum in London described the
discovery as a "big story".
He says the new species clearly does show the earliest step toward human
characteristics, but suggests that half a jawbone is not enough to tell just how
human it was and does not provide enough evidence to suggest that it was this
line that led to us.
The jawbone was found close to the area where Lucy was discovered
He notes that the emergence of human-like characteristics was not unique to
Ethiopia.
"The human-like features shown by Australopithecus sediba in South Africa at
around 1.95 million years ago are likely to have developed independently of the
processes which produced (humans) in East Africa, showing that parallel origins
are a distinct possibility," Prof Stringer explained.
This would suggest several different species of humans co-existing in Africa
around two million years ago with only one of them surviving and eventually
evolving into our species, Homo sapiens. It is as if nature was experimenting with
different versions of the same evolutionary configuration until one succeeded.
Prof Stringer added: "These new studies leave us with an even more complex
picture of early humans than we thought, and they challenge us to consider the
very definition of what it is to be human. Are we defined by our small teeth and
jaws, our large brain, our long legs, tool-making, or some combination of these
traits?"