As with most people my age, my hair is starting to turn gray.  Just at the temples right now, but I’m now on the way to gray.  Other mammals’ hair goes gray as well.  We know the biochemical and physiological basis of the process, and we know that this process has a genetic basis.  Thus, the process of graying hair can evolve!

To an evolutionary biologist like me, this immediately raises the question of whether gray hair in mammals is the result of adaptive evolution, and if so, what might the selection pressures be that favors gray hair in older individuals.

The obvious candiate is that gray hair is a social signal to other individuals of the status of the individual with gray hair.  Just like the red patches on the wings of a red-winged blackbird signals social status, gray hair might do the same in many mammals.  In fact, many of our cultural views of gray hair suggest such interpretations – the wise elder with flowing gray hair.  People are even commenting now on the graying of President Obama’s hair, now that he’s in office.

I can see a few sociology Ph.D. projects in this to test the human context of the hypothesis.

Or maybe it’s just wishful thinking by a guy who’s becoming more “distinguished”.

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