Is the following plausible or actually known to exist?
Humans, presumably in common with other mammals, have a tendency to evolve
in their own lifetime so-to-speak. They adapt themselves to their
environment during their life eg. put muscles under strain and they grow
larger to meet the demands put on them (hypertrophy), put them under no
strain (eg. by becoming a paraplegic) and they waste away (atrophy).
Similarly if you starve yourself your stomach no longer sees the need to
produce the digestive enzymes and, in fact, continues not to for some time
even if food is administered.
Similarly, the concentration of blood corpuscles is greater in people who
live at high altitude. Thus some athletes spend some time training at
high altitude to help increase their body's oxygen carrying capability.
Could EVERY aspect of our being be controlled by a kind of feedback where
the body is endlessly finding this level to reduce the amount of energy
required to keep redundant aspects of our being going? If so it would
appear than humans could adapt to survive in conditions very different to
those that we face on Earth without changing our genome.
A corollary of this if that, if this adaptation is well known to occur
during the lifetime of humans, surely it could be much stronger during
foetal development. I could imagine that a foetus that has been conceived
and developed in zero gravity would be totally incapable of coping with
normal gravity- the foetus has simply become adapted to its new environment
and can only change so much after that period. Astronauts are known to
suffer badly when they return to Earth after several months as they lose
calcium from their bones and their muscles atrophy.
Alternatively, if say rats (or any other mammmal) were to live their whole
life from conception to death in an atmosphere of, say, 10% oxygen rather
than 21% they would become adapted to it and probably find that their
levels of superoxide dismutase were abnormally low. Obviously you would
require several generations of rat gradually reducing the lvel of oxygen to
prevent the mother being suffocated.
I gues in summary what I'm suggesting is yYou could imagine that it is
nigh on impossible to tell what conditions are like on Earth simply from a
perfect knowledge of the human genome and the expertise to interpret what
it does.
