"Odysseus" wrote in message
...
Peter Webb wrote:

[snip]

So for Martians to have a genetic change which tends to make them
taller,
you have to identify a mechanism which confers an evolutionary advantage
on
taller Martians - some reason why they are more likely to survive to
child
bearing age and reproduce. (Similar to why Giraffe's have long necks). I
could not (and cannot) think of any such mechanism, which is why I said
it
would be unlikely. The only example I can think of where there may be an
evolutionary advantage from a genetic change is one I gave in my
original
post - tolerance to radiation. I don't think adaptation to lower oxygen
will
cause evolutionary pressure, unless there are people dying from
asphyxia -
which doesn't sound like my idea of a well run colony.

In general to the extent that we can control our environment and care
for those who can't fend for themselves, we cease to be subject to
natural selection as such. Other evolutionary mechanisms, like
sex-selection, may of course remain in play. But our culture
'evolves' much more rapidly than our bodies can, and its transmission
from generation to generation carries as important characteristics of
'human nature' as those determined by our genes.

--

Agreed. The OP asked if our bodies would change and we "would become red or
green". The only environmental variable that I thought we may not be able to
control would be radiation. Of course, without knowing the exact lifestyle
of a Martian colony, this is hard to verify! There may also be nutrient
problems, or problems caused by prolonged exposure to low gravity (which
affect you while you are still in the low gravity environment), or a host of
other things. I do not see these as causing large scale adaptations, as I
expect that Martians will primarily sit in air conditioned buildings
operating machinery - a rather less different environment to how I live
(from our bodies perspective) than running around the tundra wearing seal
skins vs wandering around the Australian outback.

The cultural argument is a far more compelling one, and in this sense
Martians may become "aliens" very quickly indeed. Most SF colonists are
portrayed as WASPS. However, on earth, the views and beliefs of (say) a
Muslim extremist are completely alien (and inexplicable) to a Westerner -
and I assume vice-versa. And, as you say, these changes occur extremely
quickly. Go back to America 50 years ago (1954) and interview a black
teenager. Do the same today. Notice any difference ?