RE: Earth-Like Planet around Proxima?
August 13, 2016 at 8:22 am
(This post was last modified: August 13, 2016 at 8:34 am by Anomalocaris.)
Regarding how complex terrestrial life would be under 2Gs:
2 Gravity itself probably doesn't put a tight limit on complexity of individual organism or ecosystem but probably put a appreciable limit on maximum size of any motile organism in the terrestrial ecosystem.
Reasonably well conditioned humans can lift their own body weight as additional load, and pilots can endure 2Gs indefinitely. So clearly twice earth gravity is no insurmountable structural stress barrier to terrestrial animals roughly human sized, and broadly built like earthly vertebrates using similar mineralized skeletons. They might be on average slower in ground movement under their own gravity conditions.
We know ants can carry loads 20 times their own weight and still get around fine. So it seems small but still very macroscopic terrestrial motile animals can exist at least up to 20 earth gravity from structural strength point of view.
I don't think any draft animals or animals of any other kind appreciably larger than humans can carry their own weight as additional load. So I will guess roughly human sized is near the upper limit of size of animal built along earth vertebrate lines that could get about under 2 Gs.
Of course structural and muscular strength is not the only limit. There is probably a tighter limit defined by the impact of higher gravity on the efficiency of locomotion. Sometime before gravity reaches a point where any motile animal would collapse under its own weight, motility may already cost so much energy it no longer pays for the animal to evolve or maintain motility in a terrestrial environment.
2 Gravity itself probably doesn't put a tight limit on complexity of individual organism or ecosystem but probably put a appreciable limit on maximum size of any motile organism in the terrestrial ecosystem.
Reasonably well conditioned humans can lift their own body weight as additional load, and pilots can endure 2Gs indefinitely. So clearly twice earth gravity is no insurmountable structural stress barrier to terrestrial animals roughly human sized, and broadly built like earthly vertebrates using similar mineralized skeletons. They might be on average slower in ground movement under their own gravity conditions.
We know ants can carry loads 20 times their own weight and still get around fine. So it seems small but still very macroscopic terrestrial motile animals can exist at least up to 20 earth gravity from structural strength point of view.
I don't think any draft animals or animals of any other kind appreciably larger than humans can carry their own weight as additional load. So I will guess roughly human sized is near the upper limit of size of animal built along earth vertebrate lines that could get about under 2 Gs.
Of course structural and muscular strength is not the only limit. There is probably a tighter limit defined by the impact of higher gravity on the efficiency of locomotion. Sometime before gravity reaches a point where any motile animal would collapse under its own weight, motility may already cost so much energy it no longer pays for the animal to evolve or maintain motility in a terrestrial environment.
