Just a side-comment:
Dark-skinned people are more fragile a far as lack of sun-light and a
subsequent vitamin D deficiency is concerned.
Fair-skinned people are better adapted (more sensitive to the sun-light
there is to soak up) to a sun starved existence. And they normally go brown
when exposed to sunlight during the summer.
[Besides blondness made the ancestors of Nothern Europeans that began to
look 'bland', or better, began to blend in (being less visible) against a
snowy background.
That is, as far as natural selection pressures in general has anything to do
with it. ]
For related reasons I would suspect that dark-skinned people are slightly
less 'neurochemically equipped' to live in polar regions.
P
"John H." <johnh at faraway.xxx> wrote in message
news:OXiha.256$1h6.12035 at nnrp1.ozemail.com.au...
> The story on vitamin D deficiency. Somewhat alarmist but important to
note.
> This is from the excellent science program in Aus: Catalyst. We seem to be
> good at that.
>>> John H.
>>>http://www.abc.net.au/catalyst/stories/s805444.htm> "John H." <johnh at faraway.xxx> wrote in message
> news:4niha.255$1h6.12990 at nnrp1.ozemail.com.au...> > Particularly significant given the Out of Africa Theory currently in
vogue
> > and well substantiated by paleanthropological, linguistic and genetic
> data.
> > Emerging from sunny Southern Africa approx 120,000 years ago, it is
> > estimated we were in Europe by circa 60,000 years ago. Thus our diurnal
> > variations may be more attuned to that previous sunny climate and subtle
> > variations ensue ... .
> >
> > John H.
> > "Wayne Alan Simon" <ariess at bellsouth.net> wrote in message
> > news:lSbha.71399$d15.34079 at fe06.atl2.webusenet.com...> > > Many biological systems are effected by daylight or lack thereof.
Some
> > are
> > > turned on and off via the light. Some are increased or decreased from
> > light
> > > ( various sources and wavelengths). Evolving on a planet that for the
> > most
> > > part has day and night cycles, has also allowed for various
adaptations
> or
> > > maladaptions based on the planets light darkness cycle. Of course if
you
> > > live in an area that is light half the year and dark half the year,
you
> > may
> > > find your biological systems adapted quite differently. Diurnal
> > variations
> > > in most neurohormonal and endocrine systems is the rule and not the
> > > exception. Vitamin D, as mentioned many times is just one factor of
> many.
> > > The situation is complex, and to shed a little "light" on the subject
is
> > > always enlightening!
> > >
> > >
> > >
> >
> >
>>
