Tuesday, April 03, 2018

People in West Africa Still Carry 'Beneficial' Genes From a Mystery Ancient Human Ancestor That Protects Them Against Tumors
Experts at the University of California Los Angeles are behind the finding
They devised a statistical method able to highlight abnormal genetic code
This was applied to the DNA of 50 modern Yoruba people in West Africa
Roughly eight per cent of their DNA comes from a yet unknown 'ghost' species
Hominin species Homo heidelbergensis is believed to be the likely candidate

By Tim Collins For Mailonline
Daily Mail Online
10:16 EDT, 3 April 2018

Evidence of an unknown species of human ancestor has been found hiding in the DNA of West African people.

Experts made the finding by analysing the human genome, looking for strings of genetic information that were out of place.

This revealed an inheritance of markers from an unidentified human-like species, some of which may be of benefit to their descendants - including one which suppresses the development of tumours.

Researchers believe an ancient species of hominin, known as Homo heidelbergensis, may be the most likely candidate for the 'ghost' species.

The finding was made by Arun Durvasula and Sriram Sankararaman, researchers at the University of California, Los Angeles.

They devised a statistical method able to highlight abnormal genetic code without needing the genome of the species it was inherited from.

This bypasses the need for DNA extracted from extinct African hominins as a basis of comparison.

The hotter and wetter climate on the African continent tends to destroy any preserved DNA, unlike samples of human-like species the Neanderthals and Densiovans uncovered in Europe and Asia. 

The statistical technique was applied to the DNA of 50 modern Yoruba who had their genetic information sequenced as part of the 1,000 Genomes Project.

This established that roughly eight per cent of their DNA comes from a yet unknown 'ghost' species.

While Homo sapiens may be the only hominin species alive today, tens of thousands of years ago the planet was home to a variety of human and protohuman species.

As the result of interspecies breeding, some of these species' DNA has been passed down to modern humans.

Traces of Neanderthal DNA are still found in people of non-African descent and Denisovan DNA lives on in people of Asian heritage.

Researchers also learned in 2016 that the DNA of an unknown population of archaic hominins continues to exist in Pacific Island peoples.

The Neanderthals and Denisovans have been ruled out of the equation, as we already have their DNA and there is no evidence to suggest they lived in Africa.


Homo heidelbergensis lived in Africa, Europe and western Asia between 600,000 and 200,000 years ago.

It was an early human ancestor that went extinct long before modern humans migrated to Eurasia from Africa.

Hundreds of thousands of years ago, the ancestors of modern humans diverged from a lineage that gave rise to Neanderthals and Denisovans.

Research published by scientists from the University of Utah in August 2017 now suggests that Neanderthals and Denisovans diverged from each other around 744,000 years ago - around 300,000 earlier than previously believed.

This implies that Homo heidelbergensis may have been an early Neanderthal.

Homo heidelbergensis' evolutionary tree has largely baffled scientists due to scarce fossil records.

The similarity between Neanderthal, Homo heidelbergensis and Homo sapien fossils means researchers previously thought heidelbergensis fossils were simply variants of Homo sapiens.

Modern-day pygmies, who may have interbred with the Yoruba people have also been eliminated from the process, as their DNA has been sequenced and it is not a match.

A small-brained hominin that could be found roaming around the South African plains 250,000 years ago, Homo naledi, is a possible but unlikely contender.

'I would be amazed if there was anything of them in us,' said Mark Thomas of University College London, who was not involved in the study, speaking to New Scientist about the finding.

Homo heidelbergensis was a more advanced hominin living in Africa around 200,000 years ago and a more probable candidate.

It could also be that the mystery DNA came from an isolated group of Homo sapiens or population of hominins that are as yet unknown to researchers.

Whatever the answer turns out to be, the study is a reminder that our species did not emerge from a single founding population, Professor Thomas told New Scientist

The full findings of the study are available in a paper published in the online print repository bioRxiv.


55 million years ago - First primitive 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 - 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 

2.3 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 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

Read more: http://www.dailymail.co.uk/sciencetech/article-5573301/Modern-day-people-West-Africa-carry-genes-unknown-species-human-ancestor.html#ixzz5BfWFsNW0
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