Traces of two unknown extinct human species discovered lurking in modern DNA
TWO extinct ancient human ancestors have been discovered in our DNA.
Early humans met members of the mysterious species in locations across Asia, scientists claim in a new study.
They came to their conclusion by studying "ghost" traces of ancient DNA found in modern humans.
"Each of us carry within ourselves the genetic traces of these past mixing events," said Dr João Teixeira, of the University of Adelaide.
"These archaic groups were widespread and genetically diverse, and they survive in each of us. Their story is an integral part of how we came to be."
As scientists understand it, humans began migrating into Europe from Africa around 60,000 years ago.
Humans then spread out east and west to colonise the world – meeting various human-like species on the way.
One of these was Neanderthals, who early humans mated with between 50,000 and 55,000 years ago in the Middle East.
As a result, our DNA is 2 per cent Neanderthal – but it's not the only species whose genes we've nicked.
As the ancestors of modern humans travelled further east they met and mixed with at least four other groups of archaic humans.
"Island Southeast Asia was already a crowded place when what we call modern humans first reached the region just before 50,000 years ago," Dr Teixeira said.
"At least three other archaic human groups appear to have occupied the area, and the ancestors of modern humans mixed with them before the archaic humans became extinct."
One of these groups was the ancient hominin the Denisovans, while the other two remain a mystery.
According to the new study – which also used information from reconstructed migration routes and fossil vegetation records – man met these species in spots across Asia.
One mixing event occurred around southern Asia between the modern humans and a group scientists have named "Extinct Hominin 1" (EH1).
A timeline of life on Earth
The history of the planet in years...
- 4.6billion years ago – the origin of Earth
- 3.8billion years ago – first life appears on Earth
- 2.1billion years ago – lifeforms made up of multiple cells evolve
- 1.5billion years ago – eukaryotes, which are cells that contain a nucleus inside of their membranes, emerge
- 550million years ago – first arthropods evolve
- 530million years ago – first fish appear
- 470million years ago – first land plants appear
- 380million years ago – forests emerge on Earth
- 370million years ago – first amphibians emerge from the water onto land
- 320million years ago – earliest reptiles evolve
- 230million years ago – dinosaurs evolve
- 200million years ago – mammals appear
- 150million years ago – earliest birds evolve
- 130million years ago – first flowering plants
- 100million years ago – earliest bees
- 55million years ago – hares and rabbits appear
- 30million years ago – first cats evolve
- 20million years ago – great apes evolve
- 7million years ago –first human ancestors appear
- 2million years ago – Homo erectus appears
- 300,000 years ago – Homo sapiens evolves
- 50,000 years ago – Eurasia and Oceania colonised
- 40,000 years ago – Neandethal extinction
Other interbreeding occurred with groups in East Asia, in the Philippines, the Sunda shelf, and possibly near Flores in Indonesia, with another group they have named "Extinct Hominin 2".
"We knew the story out of Africa wasn’t a simple one, but it seems to be far more complex than we have contemplated," Dr Teixeira said.
"The Island Southeast Asia region was clearly occupied by several archaic human groups, probably living in relative isolation from each other for hundreds of thousands of years before the ancestors of modern humans arrived.
"The timing also makes it look like the arrival of modern humans was followed quickly by the demise of the archaic human groups in each area."
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What do you think of this new ancestral discovery? Let us know in the comments...
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