They were the first human settlers to arrive in Australasia after our species left Africa around 60,000 years ago.

But it seems the ancestors of modern Aborigines and indigenous people from Papua New Guinea and parts of India had more illicit encounters with other species of early humans than first realised.

Analysis of DNA from modern indigenous populations in Australasia has uncovered evidence that they encountered a mysterious new human ancestor as they migrated.

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A mysterious new human ancestor has been uncovered in a DNA analysis of human migration from Africa to Australasia. Researchers from Universitat Pampeu Fabra made the discovery by sequencing the genomes of populations including the Andamanese (a family, pictured)

It appears this unknown hominin species bred with Homo sapiens as they spread from Africa and through Asia.

The study also raises questions over previous findings that modern humans populated Asia in two waves from their origin in Africa - instead backing a single out-of-Africa migration event.

A SINGLE OUT-OF-AFRICA EVENT Homo sapiens are thought to have first appeared in Africa around 150,000 years ago. Some 100,000 years later, small numbers left their homeland travelling first to Asia and then further east, crossing the Bering Strait, and colonising the Americas. It had been thought that modern humans populated Asia in two waves from their origin in Africa, around 60,000 years ago. Previous research looking at the genomes of people living today showed the Asia-Pacific arrivals mated with two hominin species they found, the Neanderthals and the Denisovans. Now, a third has been found, and this suggests the 'Out of Africa' migration was a single event. This finding indicates a common origin for all populations in the Asia-Pacific region, dating back to a single out-of-Africa migration event. Advertisement

'We show that populations from South and Southeast Asia harbor a small proportion of ancestry from an unknown extinct hominin, and this ancestry is absent from Europeans and East Asians,' the researchers wrote in Nature Genetics.

Our species - Homo sapiens - first evolved in Africa around 150,000 years ago but are believed to have ventured out of the continent around 60,000 years ago.

Scientists have been mapping the appearance of genetic markers in modern peoples to better understand how ancient humans moved around the planet.

The ancestors of Europeans are thought to have headed west after leaving Africa, mating up to several times with the Neanderthals they encountered along the way.

Modern people of European descent typically owe between one and six per cent of their DNA to these prehistoric encounters.

Homo sapiens are thought to have inherited several genetic traits that have helped to boost their immune systems and gifted tougher hair and skin to our species from Neanderthals as a result of this interbreeding.

Other research has also found that the ancestors of indigenous populations in Asia and the Pacific appear to have mated with not only the Neanderthals but another prehistoric species called the Denisovans.

Now, the new study has revealed that they may have mated with a third species.

Professor Jaume Bertranpetit at Pompeu Fabra University in Spain made the discovery after looking at the genomes of indigenous Australians, Papuans, people from the Andaman Islands and from mainland India.

They found parts of their DNA did not match any hominin species on record.

Some 60,000 years ago, modern humans left Africa, travelling first to Asia and then further east, crossing the Bering Strait, and colonising the Americas. The latest study questions previous findings that modern humans populated Asia in two waves from their origin in Africa - instead backing a single out-of-Africa migration theory

It's been many thousands of years since Homo erectus last walked the Earth, but our fossil ancestors likely had a few behaviours in common with humans today. A set of 1.5-million-year-old footprints discovered in Kenya recently are believed to below to Homo erectus

Europeans or east Asians do not have these particular DNA sequences, which suggests the third hominin met our early ancestors in south Asia or the Pacific region.

'People have speculated that there could be more ancestors to the human and these ancestors are offshoots of the Heidelberg man,' Partha Majumder, director National Institute of Biomedical Genomics (NIBMG), told IANS.

Neanderthals, Denisovans, and modern humans are all considered to have descended from Homo heidelbergensis (the Heidelberg man) that appeared around 600,000 years ago in Ethiopia.

'What we have been able to show is that there is strong possibility that there is at least one more ancestor and we have found the segments of this new ancestor, not found in either the Neanderthal or the Denisovan,' Majumder said.

THE COMPLEX EVOLUTION OF MAN 55 million years ago - First primates evolve 15 million years ago - Hominidae (great apes) evolve from the ancestors of the gibbon 8 million years ago - First gorillas evolve. Later, chimp and human lineages diverge 5.5 million years ago - Ardipithecus, early 'proto-human' shares traits with chimps and gorillas 4 million years ago - Australopithecines appeared. They had brains no larger than a chimpanzee's 2.8 million years ago - LD 350-1 appeared and may be the first of the Homo family 2.7 million years ago - Paranthropus, lived in woods and had massive jaws for chewing 2.3 million years ago - Homo habalis 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 1.6 million years ago - Hand axes become the first major technological innovation 800,000 years ago - Early humans control fire and create hearths. Brain size increases 760,000 years ago - New DNA analysis shows the first Neanderthals emerging 400,000 years ago - Neanderthals begin to spread across Europe and Asia 200,000 years ago - Homo sapiens - modern humans - appear in Africa 40,0000 years ago - Modern humans reach Europe Advertisement

'Remains of this extinct hominid have not yet been recovered, but our results provide definitive evidence that Homo heidelbergensis had given rise to multiple lineages, not just the Neanderthal and the Denisovan.'

'And we have dated the segments of the genome and it goes back to about 40,000 years ago.

'That's the third group of ancestors from whom we have descended.'

The mystery hominin may be Homo erectus or 'upright man', Professor Bertranpetit told New Scientist.

Homo erectus was believed to have been present in Asia 1.8 million and 33,000 years ago.

However, Professor Bertranpetit said there is no evidence at the moment to prove this theory.

The researchers say the footprints are indistinguishable from those of a modern barefoot human, with similar foot anatomies and mechanics.

It has been many thousands of years since Homo erectus last walked the Earth, but our fossil ancestors likely had a few behaviours in common with humans today.

In a separate study, researchers have examined a set of 1.5-million-year-old footprints discovered in Kenya, revealing new insight on how they moved and interacted.

Through new analytical techniques, the international team found that Homo erectus may have walked in the same style seen in modern humans, and likely had human-like social behaviours.

Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, along with an international team of scientists, investigated ancient hominin footprints discovered in 2009 near the town of Ileret, Kenya.

The continued efforts since the initial discovery revealed an unprecedented set of trace fossils, consisting of 97 tracks from at least 20 different individuals, all thought to be Homo erectus.

These were found over five distinct sites.

The researchers say the footprints are indistinguishable from those of a modern barefoot human, with similar foot anatomies and mechanics.

'Our analyses of these footprints provide some of the only direct evidence to support the common assumption that at least one of our fossil relatives at 1.5 million years ago walked in much the same way as we do today,' said Kevin Hatala, of the Max Planck Institute for Evolutionary Anthropology and The George Washington University.