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Unearthing The Roots of The Human Family Tree
by
findingDulcinea Staff
New research suggests that two early human populations lived in isolation of one another for up to 100,000 years, perhaps nearly evolving into two species.
30-Second Summary
The study, published in the American Journal of Human Genetics, shows that shortly after Homo sapiens emerged about 200,000 years ago a drought caused the species to separate into two distinct populations located in eastern and southern Africa.
The split occurred about 150,000 years ago and lasted between 50,000 and 100,000 years. If the study is correct, this “would be the longest period for which modern human populations have been isolated from one another,” reports the BBC.
Because humanity started in Africa, the continent’s genetic diversity “probably exceeds that of the rest of the world put together,” according to The Economist. But just how that diversity evolved is unclear. That’s why the report analyzed the mitochondrial DNA of 600 living Africans.
Mitochondrial DNA passes from mother to child, making mutations easy to trace. As a result, the study shows that the Khoi San hunter-gatherer populations of southern Africa share the mitochondrial lineage of one of the two communities, while the populations in east and west Africa, and the rest of the world, share the lineage of the other community.
The results, which come from the Genographic Project, also reinforce the findings of a Stanford University study showing that the same drought that split Homo sapiens may have also brought it close to extinction. At one point, the human population may have fallen to as low as 2,000 people.
But some scientists, such as Dr. Sarah Tishkoff of the University of Pennsylvania, say it is still to early to paint an accurate picture of humanity’s early history in Africa.
The split occurred about 150,000 years ago and lasted between 50,000 and 100,000 years. If the study is correct, this “would be the longest period for which modern human populations have been isolated from one another,” reports the BBC.
Because humanity started in Africa, the continent’s genetic diversity “probably exceeds that of the rest of the world put together,” according to The Economist. But just how that diversity evolved is unclear. That’s why the report analyzed the mitochondrial DNA of 600 living Africans.
Mitochondrial DNA passes from mother to child, making mutations easy to trace. As a result, the study shows that the Khoi San hunter-gatherer populations of southern Africa share the mitochondrial lineage of one of the two communities, while the populations in east and west Africa, and the rest of the world, share the lineage of the other community.
The results, which come from the Genographic Project, also reinforce the findings of a Stanford University study showing that the same drought that split Homo sapiens may have also brought it close to extinction. At one point, the human population may have fallen to as low as 2,000 people.
But some scientists, such as Dr. Sarah Tishkoff of the University of Pennsylvania, say it is still to early to paint an accurate picture of humanity’s early history in Africa.
Headline Links: Study uncovers genetic split in ancient humans
The split in the Homo sapiens population shows that humans “started down the path of evolving into two separate species before merging back into a single population,” reports the BBC. Dr. Spencer Wells, Director of the Genographic Project, explains: “We don't know how long it takes for hominids to fission off into separate species, but clearly they were separated for a very long time … They came back together again during the Late Stone Age - driven by population expansion.”
Source: The BBC
The Economist writes that, although our migratory history from Africa is well studied, the evolution of humankind before it spread to the other continents had been largely overlooked until now. This latest study looks at humanity’s evolution in Africa, shedding “on how modern man spread around his home continent long before he took the first, tentative steps into a bigger, wider world.”
Source: The Economist
Background: Humans nearly Extinct
A recent Stanford University report examines how the human race was nearly wiped out by a drought 70,000 years ago. "Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world," CNN writes.
Source: CNN
Related Topics: Oldest human fossils found and tracing human evolution in America
Remains found in Europe, estimated to be over 1 million years old, shed light on how early humans migrated from their evolutionary birthplace in Africa.
Source: findingDulcinea
New fossil evidence suggests that the first humans came to North America 14,000 years ago, more than 1,000 years before previously estimated.
Source: findingDulcinea
Reference: The Genographic Project and mitochondrial DNA
In April 2005, National Geographic and IBM began creating the Genographic Project, the world's largest database of human genotypes. In a short video clip, researcher Spencer Wells uses simple mouth swabs to demonstrate how four random people at New York's Grand Central Station are related.
Source: YouTube (National Geographic)
The Genographic Project page of the National Geographic Web site offers a detailed map depicting human kind’s migratory history.
Source: National Geographic
Mitochondrial DNA is a part of the cell transforms food into energy the cell can use, called ADP.
Source: Genetics Home Reference
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