It’s an SF cliche that if you grow up on a high-gravity planet you will be short, stocky and strong (see Jinx) and if you grow up on a low-gravity planet you will be tall, ectomorphic and weak. But is that just guesswork? Have scientists looked at the question?
Evolution would probably favor forms like that, but just growing up as a genetically normal human in those environments wouldn’t have as big an effect. Lifting more weight will make a human stronger, but it would take tons to make them shorter, and the result wouldn’t be pretty or walk right.
There is a different scaling for distance and mass when you make big and small versions of the same shape. It is way easier to make flimsy skinny structures if they are small. A “daddy long legs” can have a fantastically spindly shape, and it can run and fall and so forth without any harm. An elephant, on the other hand, has to be very stocky to even be able to walk quickly, and elephants are easily injured falling from small heights and very afraid of falling.
This same kind of scaling would apply for greater or lesser weight due to gravity, I would think. It’s holding the weight up that is the biggest challenge. On a low gravity planet where humans eventually evolved to be tall and thin, though, it would be more dangerous for them to run quickly. We don’t generally get hurt too badly when we run into something, but if we evolved to run much faster and to have much weaker bodies, you can see we could.
Well, no cite but I’d have to say that if humans grew up on a planet that was 1.5 g they would probably be stronger if they then went to a lower g world. Their muscle development would necessitate this I would think. Sort of the same thing if a child were constantly weightlifting. It would also stunt their growth a bit…again, it does this for children who weight lift heavily before they get their full growth. It would probably have some other effects too.
Same goes for low grav world, though don’t know about the tall part. However, think of what zero g does to the human body. If you grew up on the moon your bones and muscles wouldn’t atrophy, but they wouldn’t be as strong as they would be if you grew up on earth because they wouldn’t need to be.
That’s my guess anyway.
-XT
My sister did a project for the science fair where she (we) raised mice in a 2.5 G centrifuge. The 2nd & 3rd generations were shorter and stockier than their parents. They pretty much moved around like normal mice, climbing the walls of the cage and dropping–quite quickly!–from the ceiling.
We didn’t test their strength–couldn’t get them to do the weights thing–but one has to assume they were much stronger than normal mice, given their activity level under 2.5 G.
That is awesome. How big was the centrifuge?
Sorry, but my BS-O-Meter is dinging on this one. I’m not seeing how maintaining a 24-7 2.5 G living environment for mice would be remotely possible under the cost and technical limitations of a high school level science experiment.
It’d be tricky, but doable. What’s more dubious to me is keeping it going 24/7 long enough to get three generations - wiki says mice start breeding at around 50 days, so that’s a minimum of 100 days plus however old your last mice get. Say five months - that’s a very long-term science project.
Incidentally, my back-of-the-envelope says if you got a 5’ radius centrifuge (that’s about as big as a playground merry-go-round), you’d need the edge to be going around 14 mph. That’s not out of reach for high school, but having somewhere to build and keep the thing running for five months could be harder, not to mention power usage.
Not gravity related, but I think that it illustrates the point about what gravity would do if someone were raised in a different gravity environment than Earth. Eucalyptis trees in California are taller than those grown in Australia. The reason for this, it turns out, is that there was a fungus which attacked the trees in their native environment, and the tree had to expend a considerable amount of its energy repairing damage, rather than growing up. In California, the trees had nothing attacking them, so they were able to devote all their energy to growing taller. (A side effect of all this was that the California trees were more flammable than those Down Under. Oops.)
We know that bones under stress thicken as a result of this stress, anthropologists and forensic scientists can tell a lot about what kind of work a person did during their lives based on how the bones are built up. Someone living in a higher gravity world would, of necessity, have thicker bones, while someone in a lighter gravity world would have thinner bones. I don’t think that its too much of a stretch, based on these tidbits, to believe that a person would be taller or shorter, depending upon the gravity environment they were raised in.
I agree with astro. We need more details.
i found this which seems related