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Sunday, November 18, 2012

Lopsided Geneology

I have often wondered at how patriarchal our society has been all through the centuries and – though changes are occurring slowly - how women have allowed themselves to remain so dominated by men even up to the present . In my post ‘On Being Female’ I talked about some of the reasons why this could have happened and I recently came across another.  
Aristotle, one of the most important thinkers in the Western world, not only in philosophy but also in the sciences, profoundly influenced scholarship well into the 17th century.  In 335 BC he proposed  that during conception, it was the man who ‘inoculated’ a woman with his child and that the woman's part was simply to sustain and succor the infant. When a child was born female or did not look like its father, it was explained away as ‘interferences’ that unfortunately occurred in the womb. It is no wonder that this idea was perpetuated since both Christianity and Muslim religions picked up on it and besides, men possessed the all the status and power in our society and in many cases still do. An indication of how pervasive this way of thinking is, just consider that when she marries, a woman commonly takes on her husband's surame as do all of  their children.
Having spent some time in the last couple of years creating genealogies for each of my parents  - tracing the origins of their families back to their coming to North America – I became acutely aware that when she married a woman lost her identity genealogically. Even her maiden came from her father.  It makes for tidy record keeping but since we know now that the mother contributes equally in passing on her DNA characteristics to her children, half a person’s biological history is routinely lost .
It turns out that the geneticist Bryan Sykes used a very neat and infallible way to trace one’s ancestry using woman’s identity only. He used the DNA in a type of bacteria called  mitochondria that have found their way into every cell in our body. They are vitally important in our metabolism because they are able to use the oxygen we breathe and, by combining it with food we eat, produce the energy needed by our cells  to keep us alive.  

In the conception of a child, the relatively large mother’s egg [pictured on the right] contains hundreds of the mitochondria while the male sperm contains only the father’s DNA.  Thus the mother passes on to each of her children, male or female, her own mitochondria. Each piece of mitochondria containing a relatively small piece of DNA whose code can be easily read by a geneticist. 

As in all living matter there can be the occasional mutation – they occur  on average about every 10 thousand years – so, depending on how many mutations  there have been and in what population they occurred,  it is possible to conclude that our species arose some 200.000 years ago, probably in south eastern Africa. Using our types and numbers of mutations over the eons, it is also possible to construct a type of genetic tree through the mitochondria of females. Our own mitochondrial fingerprint, identifies us as belonging to one branch of the Homo Sapiens tree shown on the left.. These branches are being given names and it has been suggested that in future a person will have three names - a first name, a name indicating our mitochondrial branch and a surname.  Rie

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