Xes, Sexes and Mitochondrial DNA

The X post  is always a difficult but exceeding fun post to research and write for the A to Z Blogging Challenge.  The X post that I wrote a while back, in April 2012, called The Exceptional World of The Letter X, on my personal blog is still a favorite of mine.  Today I expand upon the X is for X chromosome element that I alluded to in this earlier post as well as brief mention of mitochondrial DNA. From the earlier post:

the X-chromosome that I like to think of as the complete and whole version of the poor misshapen Y-chromosome. This New York Times article about the X-chromosome is a fun read and a great link for Mother’s Day posts.  The need for those is approaching with great speed.

There are actually two distinct ways that genetic female information is transmitted from generation to generation.  Science is finding out more and more about how these function all the time.  Most DNA is found within the nucleus of the cell, but there is DNA within another part of the cell, the mitrochondrion, too.   The mitochondria are membrane-bound organelles found in all cells of every multi-celled creature. Mitochondria convert energy derived from chemical nutrients into ATP or chemical energy that fuels cell functions.
As we talk about genetics and archeology we do need to understand the basic biology of which we speak.  We do not have to be experts but understanding whether we are talking about sex-linked genetic materials that are actively manipulated, rearranged, and turned on and off during reproduction, or about the mitochondrial DNA that flows to individuals directly from the mother.

At one point archeology and human genetic information were at odds and suggested very different timelines for human evolution and migration of human populations around the globe.  But relatively recent understanding of molecular mutation rates, how the genetic timeline of human evolution is measured, has slowed the rate of proposed of genetic mutation in human populations by half, putting genetic and archaeological timelines on the same page, per human history, if not the same paragraph.
The only points in time over which I could find some agreement about what humans were doing include the following:

• 150 – 125,000 years ago we were with our last common mother in Africa.
• 75,000 – 60,000 years ago the last mother of all non-Africans was somewhere beyond the African Continent.
• 30,000 years ago we were creating sacred images of women.
• 10,000 years ago we settled down and took up horticulture.
• 5,000 years ago  in the Early Bronze Age, patriarchal religions as evidenced by Abraham and monotheism, began to take take root and spread.

To talk about history, archaeology and biology requires basic understanding of agreement in the sciences.  A very good article that discusses haploid testing and “clans” can be found on DNA-explained.com.