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vrabinec
04-21-2009, 07:24 PM
Let's say it's a world with around 80-90% of Earth's gravity. People would grow up with fewer muscles. I'm thinking they might be just slightly taller on average. The lungs would be slightly smaller, since the body doesn't need to burn as much fuel to function. Anything else?

geardrops
04-21-2009, 10:29 PM
There's a potential for higher body fat percentages -- depending on the availability of food -- being the day-to-day strain they receive on their body is lessened.

vrabinec
04-21-2009, 10:52 PM
Good point. And probably taller fences since people could jump higher if they happed to develop their muscles to their full Earthly potential.

Sarpedon
04-21-2009, 11:12 PM
And the air would probably be thinner, so everyone would have high altitude lungs. I don't think the lungs would be smaller.

And probably more hat wearing, and darker skin because of greater UV exposure.

Fewer back problems, lower blood pressure, maybe bigger diaphragm for breathing. Barrel chests.

vrabinec
04-21-2009, 11:52 PM
More UV exposure? That would have more to do with how much of an atmosphere it would have. I dunno. Is the amount of atmosphere a planet can carry directly proportional to the mass? I mean, obviously you have to start out with an atmosphere, but I don't know if it would start to lose it one the space within the panet's gravitational field was saturated. Gotta try to look that one up.

Lhun
04-22-2009, 12:00 AM
From an evolutionary perspective probably also weaker bones, and slower reaction speeds. Things don't fall as hard and fast. Though i don't think this would be changed by simple physiological adaption. (i.e. takes a few hundred millenia to show up)

Julie Worth
04-22-2009, 12:19 AM
They could carry more fat, so thus the obesity epidemic would spread to far-flung worlds.

geardrops
04-22-2009, 12:33 AM
Is the amount of atmosphere a planet can carry directly proportional to the mass?

More mass = more gravity = it can "hold on" to more atmosphere (air).

Sarpedon
04-22-2009, 05:19 PM
Whether or not there will be less air in the atmosphere (which is probable)

lower gravity will mean lower atmospheric pressure. Which will translate to the equivalent of Earth's high altitude lungs and other adaptation.

Lower pressure would probably also mean less standing water, and drier conditions, unless I miss my guess.

Maryn
04-22-2009, 06:39 PM
I could make, at best, an educated guess at the author, but I read something maybe 30 years ago in which heart patients were relocated to low-gravity planets (or satellites?) because reduced gravity meant the heart did not have to work as hard and could heal. At the time, it seemed to have been carefully researched and fully plausible.

Which gets me thinking about what other benefits there might be, medically, in reduced gravity. I'm no medical professional, but arthritis suffering could lessen as the apparent weight on joints in motion is lessened. A broken bone will heal no faster, but might bear weight sooner as it mends. Hips and knees might last an entire lifetime for nearly everyone, so the elderly, with their increased lung capacity and less stressed hearts, could be far more healthy and active than they are here on Earth.

Maryn, who used to read a lot of sci-fi

vrabinec
04-22-2009, 06:49 PM
Excellent, Maryn. I'd be willing to bet that the elderly would walk as hunched over either.

Judg
04-22-2009, 06:49 PM
Lower bone density and less muscle mass, for sure. And it would be an immediate physiological adjustment, not a long-term genetic one. You are basically looking at all the same physiological effects as weightlessness, just to a lesser degree. There are all kinds of hard data on that available.

For people born and raised in a lower gravity environment, it is assumed that they would grow taller. Obviously this has never been tested in real life.

Kim Stanley Robinson's Mars trilogy deals with this (and a gazillion other hard science topics) if you're interested in seeing what's already been done.

Lyra Jean
04-22-2009, 08:00 PM
Lower bone density and less muscle mass, for sure. And it would be an immediate physiological adjustment, not a long-term genetic one. You are basically looking at all the same physiological effects as weightlessness, just to a lesser degree. There are all kinds of hard data on that available.

For people born and raised in a lower gravity environment, it is assumed that they would grow taller. Obviously this has never been tested in real life.

Kim Stanley Robinson's Mars trilogy deals with this (and a gazillion other hard science topics) if you're interested in seeing what's already been done.

Kim Stanley Robinson's Mars trilogy is good.

benbradley
04-22-2009, 08:29 PM
I could make, at best, an educated guess at the author, but I read something maybe 30 years ago in which heart patients were relocated to low-gravity planets (or satellites?) because reduced gravity meant the heart did not have to work as hard and could heal. At the time, it seemed to have been carefully researched and fully plausible.

Which gets me thinking about what other benefits there might be, medically, in reduced gravity. I'm no medical professional, but arthritis suffering could lessen as the apparent weight on joints in motion is lessened. A broken bone will heal no faster, but might bear weight sooner as it mends. Hips and knees might last an entire lifetime for nearly everyone, so the elderly, with their increased lung capacity and less stressed hearts, could be far more healthy and active than they are here on Earth.

Maryn, who used to read a lot of sci-fi
Yes, those are apparently the positive effects.

Lower bone density and less muscle mass, for sure. And it would be an immediate physiological adjustment, not a long-term genetic one.
Well, "immediate" would be over weeks and months (and perhaps measurable in days), though that's certainly immediate compared to genetic change.

You are basically looking at all the same physiological effects as weightlessness, just to a lesser degree. There are all kinds of hard data on that available.
Yes, a change in gravity may have both positive and negative effects. Those in space for more than a few days have to do exercises to keep a reasonable amount of muscle and bone mass.

What's the current record for continuous time in space? I think there have been a few who have been in it for over a year, and the "standard" tour of duty at the International Space Station is something like six months.

I've heard there's only one person who has walked off the Shuttle (or the Russsian vehicle) unaided after having been in space for two weeks or longer and he/she is a triathlete.

For people born and raised in a lower gravity environment, it is assumed that they would grow taller. Obviously this has never been tested in real life.
This would be interesting to test for and see how to separate out for other factors such as diet, especially if the gravity difference is fairy small (10 percent or less). I've heard how Japanese were historically shorter than Westerners, but as their children starting eating more of a Western diet, they outgrew their parents and became closer to Western height (they surely also have greater incidence of cancer and heart disease than their parents due to the Western diet, but that's another topic).

Judg
04-22-2009, 09:01 PM
Things are always complicated, aren't they? So many things are trade-offs.

And yes, by immediate I meant in comparison to generational or genetic change.

Dommo
04-23-2009, 04:56 AM
The big ones as far as people are concerned would definitely be the loss of bone mass and muscle. That's already a common occurrence for astronauts.