--- In
cybalist@yahoogroups.com, "Patrick Ryan" <proto-language@...>
wrote:
> Color (of skin, hair, and eyes) _is_ a genetically inherited
feature.
Our skin has to perform a complex juggling act: on the one hand it
needs to admit a certain amount of ultraviolet B for the synthesis of
vitamin D, on the other hand it needs to keep out ultraviolet B to
prevent damage leading to cancer. Every climate has an optimal skin,
which is why you have these clines roughly correlated with latitude
and other climatological factors, such as cloud cover. Migrations to
different zones subvert the balance, setting up selective pressures
that will tend to resotre the balance given enough time.
These effects are of great practical importance in the modern world.
In Holland, for instance, health workers have to see to it that
children of Maroccan and Turkish parents get a lot of sun; in
Australia a huge propaganda effort is needed to keep the red-heads
covered on the beaches.
But selection takes time. If a group moves from the Eurasian steppe
(which is a fairly sunny place to begin with) to the tropics (which
are downright killing) you expect them to remain recognizable as such
for a fairly long time, of course as long as they practice
segregation, which is what the Indian caste system is all about.
At least this is the way I understand things. There is nothing
inherently racist in the story or inherently upperclass in a light
skin.
Willem