Re: Good mutations

George Murphy (
Sat, 29 Nov 1997 08:08:55 -0500

Glenn Morton wrote:
> Hi John,
> At 09:54 PM 11/27/97 -0600, John P. McKiness wrote:
> >Just a quick note on you statements above. I believe we white folk are the
> >ones who need to be thankful for the mutations that lead to our light skin
> >because dark skin, in all likely hood, is the original condition in our
> >species. Higher melanin content is the norm in the tropics and subtropics.
> >Light skin pigmentation is the result of beneficial mutations within mid to
> >high latitude populations. The need for vitamin D and lower light
> >intensity requires less pigment (unless we can get vitamin D somewhere
> >else). Less pigment on the other hand would be a harmful mutation in the
> >tropical savanna of Africa.
> I have seen some controversy about this. Apparently, even with only 3 hours
> of sunlight per day even at high latitudes, blacks can produce their maximum
> quota of vitamin D. (John H. Relethford, Fundamentals of Biological
> Anthropology, (Toronto: Mayfield Publishing Co., 1994), p. 112) The
> occurrence of rickets among blacks increased when they moved to the cities
> and were no longer spending those 3 hours outside in the sun. There is
> another possible selective need for light skin at high latitudes:
> "Recently, there has been some evidence that skin colors are linked to
> differences in the ability to avoid injury from the cold. Army researchers
> found that during the Korean War blacks were more susceptible to frostbite
> than were whites. Even among Norwegian soldiers in World War II, brunettes
> had a slightly higher incidence of frostbite than did blonds."~Boyce
> Rensberger, "Racial Odyssey," in Elvio Angeloni, Editor, Annual Editions
> Physical Anthropology 94/95,(Sluicedock,Guilford, Conn.: The Dushkin
> Publishing Group, Inc., 1994), p.40-45, p. 42
> Blue eyes are also more sensitive to red light and dimmer illuminations than
> brown eyes. Ibid. p. 42-43

Again, what's good & what isn't depends in large part on the
George Murphy