Originally posted by daryen:
My question is not why you would want to (from a gaming perspective).
Again - unless there are overriding climatic or other reasons - the assumption is that height is an advantage. Perhaps this is the assumption you're questioning.
Height gives a longer visual reach and longer limbs allow for faster locomotion and a larger 'zone of control.' Human females seem to prefer taller males for mating - and ultimately that may be all of the 'advantage' required.
My question is, where is the scientific basis for this automatic assumption that otherwise pure strain humans will "adapt" to become taller if left to develop on a low-G world?
If height is, in fact, an advantage then removing one of the current limitations on height (excessive blood pressure increase) would lead to that advantage being expressed to a greater degree - at least until it again runs up on the blood pressure limitation or some other limit.
For example, let's go back in time to 1000 AD, miraculously give Mars an Earth-normal atmosphere (6), transplant several hundred thousand humans over there (with associated elements of biosphere to support them) and let them incubate for 1000 or so years. By most sci-fi rules (not just GURPS), the decendants of these otherwise normal humans will automatically be weaker, less hardy, and taller than the decendants left on Earth.
Firstly - 1000 years is just a drop in the bucket by evolutionary standards - so not a lot is going to happen in a thousand years unless there is some *strong* biological pressure involved - like only the best basketball players get to eat (strong pressure for height) or there is something that eats only individuals above 4'10" (strong pressure against height).
There would probably be some environmental influance on development - take twins seperated at birth. One is raised in a 1g environment and one is raised in a 0.6 G environment. The 'martian' twin will probably grow taller just because it's easier to grow. We know that the bones and muscle mass of people in a 0G environment change radically - so it's not to far off the path to conclude that individuals
raised in a 0.6G environment are going to develop differently as well.
Nevertheless - take that 'martian' population after 1000 years, bring them home to mother earth and in a couple of generations you won't be able to tell them apart from the general population. The gene pool won't have changed signifigantly - just the environment.
Up the time scale to 50,000 or 100,000 years and you'll see some actual
changes. Just as living in the cold northern latitudes has made my anscestors naturally paler - you're going to see some changes in your 'martians.'
In the abscence of other strong pressures to the contrary - the 'martians' are going to run weaker and taller. Not necessarily less robust - i.e. STR will be lower but it does not follow that END has to be as well. If the atmosphere is thinner (a natural consequence of a lower gravitational field) they'll probably be MORE robust vs. normal humans.
Maintaing muscle mass *COSTS* you. It's expensive in terms of calories and nutrients. The tasks an individual needs to accomplish drive muscle mass and humans tend not to maintain additional muscle mass if it is not neeeded (ask any body builder who skips 6mo at the gym). Your body does not want to feed it, plain and simple.
In a lower G environment one needs less muscle mass to accomplish any given task - be it walking around to doing pushups to just standing around and pumping oxygen to the brain.
So you are going to maintain less muscle mass because you don't need it. If you don't need it your body is not going to feed it.
Over an evolutionary time scale you would probably see a decrease in the overall ability of the 'martians' to maintain a 'typical' Earthman's muscle mass for the simple reason that individuals who would have died due to the defeciency in a 1G environment are going to survive and reproduce happily in 0.6G. In fact they might even do better due to requiring less calories in the long run.
Does that mean that all of the 'martians' won't be able to bulk up to your or my size? No, just that the muscle mass bell curve will have taken a shift towards the fashion model end of the scale.
Why? Will this necessarily happen? What is the basis for this incredibly pervasive assumption?
This is all prefaced by the statement "all other things being equal." If lifting elephants every day is a necessary survival trait for the 'martians' then those guys are going to be STRONG regardless. If it's insanely cold and people with a lower surface area to volume ratio are going to survive much better, then they WILL be rounder like the inuit.
So they're not guarenteed to be long and willowy - it's just a lot more likely - if you assume height is an advantage and all other things are equal.
HTH
--michael
