Saturday, April 26, 2008

Human Origins in Africa - Weekly Science update

Palentologists and Population Geneticists have discovered and confirmed that our human ancestors originated on the dark continent. "A team of Genographic researchers and their collaborators have published the most extensive survey to date of African mitochondrial DNA (mtDNA). " The genetic material of the mitochondria, or powerhouse of the cell, is high conserved and has a very low mutation rate compared to nuclear or regular DNA. When sperm and egg unite, they each bring their fair share of nuclear DNA - 23 chromosomes. 22 Somatic or body chromosomes and 1 set of sex chromosomes to determine the gender of the baby. The chromosomes are the packages of ALL of your genes. Both the egg and sperm are single cells, but the egg, which is a bit larger than the sperm, also houses other cell organelles, including the mighty, mighty, mitochondria. So if you did a cheek swab, a la Maury Povich style, your mitochondrial DNA is exactly your mom's so on down the line.

"Mitochondrial DNA, inherited down the maternal line, was used to discover the age of the famous 'mitochondrial Eve' in 1987. This work has since been extended to show unequivocally that the most recent common female ancestor of everyone alive today was an African woman who lived in the past 200,000 years. Paleontology provides corroborating evidence that our species originated on this continent approximately 200,000 years ago."

So this backward game of chasing down the mtDNA has to deadline somewhere - that's to mitochondrial Eve. But the researchers found that there are 2 dead ends. Both deadline on the African continent, but separated geographically - eastern and southern Africa - and over many tens of thousands of years.

Check out the full article on ScienceBlog: Humanity nearly split in two, study finds

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