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The Woman Who is the Mother of Us All
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This woman is thought to be the “mother” of all humans alive today. Seems like a big claim for scientists to make. So how do they know this? The simple explanation is that when an egg is fertilized by a sperm, the DNA from the father and mother join together in a process known as recombination. Certain DNA is only passed down from the mother or father. All mitochondrial DNA (mtDNA) come exclusively from the mother, as an exact copy. Over time however, there will occur predictable mutations to mtDNA. Biologists can compare samples from individuals to determine how closely they are related- the fewer these predictable mutations, the closer the relationship. The predictability of these mutations also allows biologists to estimate the time at which a certain mutation (i.e. ancestor) lived. Beginning in 1987, several studies have been conducted that show all humans alive today have the same female ancestor and she lived approximately 200,000 years ago.
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