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Hidden in genes are insights into how modern humans spread across the world
Photo: Andrew Brookes/Cultura RF/Getty Images
All people in this world are related to each other.
A new family tree of Homo sapiens developed by scientists at the University of Oxford shows exactly how.
They call it the "genealogy of man."
The work was presented in the journal »Science«.
"Human history is written in our genes," said the study's lead author, Anthony Wilder Wohns of Massachusetts Institute of Technology and Harvard University.
"And the reconstruction of our genealogy enables us to read this story."
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This family tree of modern man is said to be the most comprehensive ever created.
It is based on modern and partly ancient genome data from more than 3,600 people from all over the world.
And it should help to understand how modern humans spread across the planet.
Genetic Traces of Homo erectus
The roots of Homo sapiens therefore go back to north-east Africa - and to a time long before the first modern human could be spoken of.
"The earliest ancestors that we have been able to identify go back to a geographic location in present-day Sudan," Wohns said.
These ancestors would have lived at a time going back as far as a million years and beyond.
"This is much older than current estimates of the age of Homo sapiens."
The age of modern man is estimated at 250,000 to 300,000 years.
From this follows, according to Wohns: "Parts of our genome were inherited from individuals that we would not recognize as modern humans."
The scientist explained that the genetic contribution, which is millions of years old, probably came from the species Homo erectus.
Homo erectus, which lived from about 1.9 million years ago to about 110,000 years ago, was the first species in the human evolutionary line to have body proportions similar to our own.
"Large amounts of Denisova ancestors"
The study, led by Oxford University's Big Data Institute, also shows how extinct human species have left genetic descendants among modern-day humans around the world.
A genetic heritage of the Denisovans and the Neanderthals can be found in the genome data, but not in Africa.
"For example, people in Papua New Guinea and Oceania have fairly large numbers of Denisova ancestors," Wohns said.
But even people living in Europe would have some ancestors who looked like these ancient people.
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The researchers wanted to understand how genetic mutations that occurred in the ancestors of modern humans and were passed down through the generations to the present day.
The parts of the genome in which these mutations occur could also be traced back.
The findings could help clarify when and where important population developments occurred in the past - such as the great "Out of Africa" migration, which took Homo sapiens to distant areas outside the African continent: The most important migration probably took place about 72,000 years ago.
Other studies had previously shown that groups of Homo sapiens had left Africa at various times in the past.
When did humans reach America?
The study also suggests that certain human species may have settled in America and Oceania much earlier than the earliest archaeological evidence of human presence in these regions suggests: ancestors may have existed in America as early as 56,000 years ago.
A "significant number of human ancestors" probably lived in Oceania - especially in Papua New Guinea - as early as 140,000 years ago.
The scientist Wohns pointed out, however, that the method of the investigation did not provide clear evidence.
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