Dna mutations dating migrations lesson
Dna mutations dating migrations lesson - giessen dating
The "Eve" in question was actually the most recent common ancestor through matrilineal descent of all humans living today.
So the fertilized egg contains a mixture of the father and mother's nuclear DNA and an exact copy of the mother's mt DNA, but none of the father's mt DNA.Mitochondria are tiny structures that help cells in a number of ways, including producing the energy that cells need.Each mitochondrion—there are about 1,700 in every human cell—includes an identical loop of DNA about 16,000 base pairs long containing 37 genes.Go to "Tracing Ancestry with Mt DNA" (Requires Flash plugin) Go to non-Flash version of "Tracing Ancestry with Mt DNA" Let's get back to "Eve." The ancestor referred to in the 1987 Nature article can be more precisely stated as "the most recent common ancestor through matrilineal descent of all humans living today." In other words, she is the most recent person from whom everyone now living on Earth has inherited his or her mt DNA.This certainly does not mean that she is the ancestral mother of all who came after her; during her time and even before her time there were many women and men who contributed to the nuclear genes we now carry.Finding mitochondrial ancestors Even though everyone on Earth living today has inherited his or her mt DNA from one person who lived long ago, our mt DNA is not exactly alike.
Random mutations have altered the genetic code over the millennia. For example, let's say that 10,000 years after the most recent common ancestor, one of the mt DNA branches experienced a mutation.And since they now had an idea of how much the mt DNA had changed from the ancestor's, all they needed was the mutation rate to determine the age of the ancestor.For instance, if they took the mutation rate to be one in every 1,000 years and knew that there was a difference of 10 mutations between the mt DNA of people living today and the mt DNA of an ancestor who lived long ago, then they could infer that the ancestor lived 10,000 years ago.The result is that mt DNA is passed on only along the maternal line.This means that all of the mt DNA in the cells of a person's body are copies of his or her mother's mt DNA, and all of the mother's mt DNA is a copy of her mother's, and so on.These chromosomes hold the vast bulk of genetic information that you've inherited from your parents.