Bronnen bij De toekomst: historisch uitsterven
Er zijn sterke aanwijzingen dat in de geologische historie de mensheid, met
enig toeval, al eerder uitgestorven had kunnen zijn:
Humans nearly wiped out 70,000 years ago, study says
Drought in Africa reduced population into small, isolated groups, study says |
Separate study says number of humans may have fallen to 2,000 | Analysis: Humans
banded together again in Stone Age, increased in numbers | Migrations out of
Africa appear to have begun about 60,000 years ago
Human beings may have had a brush with extinction 70,000 years ago, an extensive
genetic study suggests.
The human population at that time was reduced to small
isolated groups in Africa, apparently because of drought, according to an
analysis released Thursday.
The report notes that a separate study by researchers at
Stanford University estimated the number of early humans may have shrunk as low
as 2,000 before numbers began to expand again in the early Stone Age.
"This study illustrates the extraordinary power of genetics
to reveal insights into some of the key events in our species' history," Spencer
Wells, National Geographic Society explorer in residence, said in a statement.
"Tiny bands of early humans, forced apart by harsh
environmental conditions, coming back from the brink to reunite and populate the
world. Truly an epic drama, written in our DNA."
Wells is director of the Genographic Project, launched in
2005 to study anthropology using genetics. The report was published in the
American Journal of Human Genetics.
Previous studies using mitochondrial DNA -- which is passed
down through mothers -- have traced modern humans to a single "mitochondrial
Eve," who lived in Africa about 200,000 years ago.
The migrations of humans out of Africa to populate the rest
of the world appear to have begun about 60,000 years ago, but little has been
known about humans between Eve and that dispersal.
The new study looks at the mitochondrial DNA of the Khoi and
San people in South Africa, who appear to have diverged from other people
between 90,000 and 150,000 years ago. ...
Eastern Africa experienced a series of severe droughts
between 135,000 and 90,000 years ago, and researchers said this climatological
shift may have contributed to the population changes, dividing into small,
isolated groups that developed independently. ...
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Klimaat & Milieu lijst
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(bron 24 apr.2008); 13 aug.2010