Would a human being be able to run faster, jump high, etc. if the gravity on Earth weakened? I'm assuming a weaker gravitational pull would cause the muscle to deteriorate because the body no longer needs that muscle?? Would humans have grown to larger heights if the Earth had weaker gravity? Would things fall slower? How would it affect things like water or trees and plants?

Could stronger winds possibly compensate?? Like if the gravity was weaker, muscle mass would decrease, but if a constant strong wind were to blow, could it force the body to build up muscle to withstand it? Would the stronger winds cause mountains and hills to deteriorate?

Thank you.

  • $\begingroup$ Weakened by how much? $\endgroup$
    – HDE 226868
    Commented Sep 20, 2015 at 22:49
  • $\begingroup$ For how long is "gravity weakened"? Is it that tomorrow's gravity is unusually-weak, or that we evolved on a planet with weaker gravity? $\endgroup$
    – nitsua60
    Commented Sep 24, 2015 at 3:01

3 Answers 3


Assume: Current humans, in their current form, on an Earth with somewhat less gravity. Say .75g

We would jump a third higher.
Be able to lift a third more.
Climb a lot easier.
Be a bit more clumsy, because inertia and weight will feel mismatched.
Fall more often, but not quite as badly, because of the same clumsiness and reduced traction, but slower running and falling speeds.
Walk further before exhaustion, as walking requires less effort.
Run slower, because inertia is the same but traction and ground contact time are reduced.

Pretty soon, our muscles will atrophy to the point were all but the last item are nulled out.

Assume: Humans, with normal genetic heritage, but born and raised on a lower-gravity Earth.
Will grow quite a bit taller on average.
Will have slightly worse reflexes, simply because they are never trained at the same pressure as under full gravity.
Will walk faster, because of less effort by fully acclimated and longer legs.
Will run slower, because with the taller bodies they will likely mass even more, but still have less traction.
Will jump.... about the same? Possibly a bit higher. They have longer legs, and need to fight less gravity, but will have more mass to hoist and weaker muscles to do so with.

You also ask about water.
Water is gravity in motion.
With less gravity, water will flow slower and fall slower, in direct proportion to the reduced gravity.
Waves will be higher but slower. Again, in direct proportion to the gravity for speed, and roughly inverse squared gravity for height. (1/2 gravity makes for 3-4x as high waves, moving half as fast)
Trees would be much taller, as they both require less trunk strength to lift the tops, and capillary effect would be able to lift water higher, easier.

P.S. If you actually edit the Earth's gravity, remember that effective air pressure is the direct result of the weight of the air in the atmosphere above you.
If you halve the gravity but leave the atmosphere untouched, you will also have half of the sealevel air pressure. Which will soon kill almost every insect and mammal in sight. (it's equivalent of 18000ft altitude)


It's very likely that muscles would deteriorate, but it is hard to say exactly how much.

A lower value of gravity would indeed let your characters jump higher, but their running speed would not change (it might actually get slower as they wouldn't have much good grip on the ground). Also notice that here we are assuming the muscle deterioration has not taken place yet. If muscles have accordingly deteriorated, your characters' jumping would be dependent on their muscle power. See, a kangaroo can jump far higher and longer than a human even under the current gravitational field. So it depends not only on gravitation, but your muscle power too.

Things would fall slower, yes. That's right.

Stronger winds would not facilitate muscle growth. A very strong man weighing 100 kg would be swept away by a strong wind exactly as a large lump of clay of the same mass (and density).

Yes, stronger winds would cause faster erosion of geographical features such as mountains and hills.

  • 2
    $\begingroup$ it's more than likely, it's been observed during long duration space missions on board space stations. $\endgroup$
    – jwenting
    Commented Sep 21, 2015 at 10:03
  • $\begingroup$ I was aware that the immune system underwent gradual deterioration, but I didn't know a weak gravitational medium also had measured effects on bone mass and muscles. $\endgroup$ Commented Sep 21, 2015 at 11:17
  • 1
    $\begingroup$ ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930003131.pdf $\endgroup$ Commented Sep 21, 2015 at 18:05

muscle deterioration speed might be different, but all life would have evolved a different way, but lets assume muscles, bones, etc. are the only thing that changed differently, then we get a different story,


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