Tuesday, November 23, 2010

Genetics, a Hairy Topic

First, because R is a girl, she has inherited mitochondrial DNA that can be traced back to her great great great grandmother. Technically, you can go waaaaaaaaayyyy far back in time following matrilineage (every mother will not have a daughter, but every daughter has to have a mother), but great great great grandmother was adopted, so details about her biological mother are unknown.

Second, my friend had linked to this crazy article on facebook, and something it said got me thinking about redheads, and how my daughter and I are part of this group. I looked up red hair on Wikipedia and learned some interesting stuff:

- Approximately 1% to 2% of the human population has red hair. In the United States, it is estimated that 2-6% of the population has red hair. This would give the U.S. the largest population of redheads in the world, at 6 to 18 million, compared to approximately 650,000 in Scotland and 420,000 in Ireland. {I found this fact surprising, but it makes sense when you take the size of the US into account versus the sizes of Ireland and Scotland.}

- Red hair is associated with fair skin color due to low concentrations of eumelanin throughout the body of those with red hair. This lower melanin-concentration confers the advantage that a sufficient concentration of important Vitamin D can be produced under low light conditions. {Vitamin D-licious!!}

- Two studies have demonstrated that people with red hair have different sensitivity to pain compared to people with other hair colors. One study found that people with red hair are more sensitive to thermal pain (associated with naturally occurring low vitamin K levels),[38] while another study concluded that redheads are less sensitive to pain from multiple modalities, including noxious stimuli such as electrically induced pain. {I was quite fascinated by this fact. Pain is sensed by your biological nervous system, so it makes complete sense that pain tolerance can differ from person to person due to your specific genetic makeup. I hadn't ever considered that before.}

Something I wanted to mention here about my hair is that I was strawberry-blond as a kid, but it turned a darker auburn as I grew older. Once it turned so dark, I didn't think I could really consider myself a "redhead" anymore, since my hair wasn't the fiery orange of, say, a native Irish lass. Did my brownish hair with a hint of golden red really qualify me as a redhead? According to Wikipedia, yes: "Red hair (also referred to as titian or ginger hair) varies from a deep burgundy through burnt orange to bright copper." Of course there are different shades of red!! In one sentence, Wikipedia threw away years of insecurity about my hair. :-D Oddly enough, instead of starting with strawberry-blond hair that darkens like mine did, R is starting out with auburn hair exactly the same shade as my hair now. I wonder what color it will be when she grows up. At least I know with certainty that I can call her my little redhead. ^_^



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