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So there are a lot of questions out there that talk about how species would evolve on terrestrial planets with higher or lower gravity than earth. All of those are very interesting and have some great answers. They even address how a dominant species might evolve similar to how humans evolved on Earth. A decent question was posted here, but my situation varies in a few ways. My question is how humans would evolve if moved to those planets.

If humans settle planets with higher gravity (let's use a planet with 2G and a planet with 4G) what changes to human physiology might happen on these planets after hundreds of thousands of years through evolution?

I understand that there are many forces in effect here, most importantly the local species and evolutionary patterns already established on those planets. Let's assume there are no significant changes here from earth, and no competing sentient species. I am trying to isolate the changes encouraged by gravity specifically. I am assuming no genetic enhancement or body modification on part of the humans, relative isolation of the gene pool (the humans are dropped off and separated from humans on other planets), and the resources for the humans to survive long enough to evolve.

On these planets let's assume that there is a similar orbit, similar relative time, and a similar atmosphere to earth wherever possible. Essentially it is earth with higher gravity.

With all of this stated I'll ask my question again:

What changes to human physiology should be expected if isolated humans were allowed to evolve on terrestrial planets with higher gravity? Namely 2G and 4G planets similar to earth in other aspects.

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  • $\begingroup$ In the question that is referenced as a duplicate it specifically states "I'm not interested in evolutionary changes as a result of selection over time in that environment". Since I am specifically interested in that subject I figured this was a different question. $\endgroup$
    – Logan Kitchen
    Commented Jun 22, 2017 at 20:55
  • $\begingroup$ There is also another related question, but it talks about modifying the human body with machinery, genetic modification, and enhancement surgery. Since I specifically excluded such modifications from my scenario I figured it was significantly different from that question as well. $\endgroup$
    – Logan Kitchen
    Commented Jun 22, 2017 at 20:58

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The main issue here is the fact that everything will be much, much heavier.

We're talking about increased demands on the muscular and skeletal systems. Everything now weighs anywhere from 2-4 times heavier; the heart must work harder to pump blood, the legs and arms weigh heavier themselves, anything carried (babies included) will weigh more, and so on.

If humans survive long enough to evolve, I would expect them to be more muscular, having an increased muscle size (including their heart and diaphragm). They may also become shorter, more stocky, and their bone structure may change to accommodate the larger loads their bodies regularly undergo.

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    $\begingroup$ Yep, space dwarves $\endgroup$
    – Andrey
    Commented Jun 21, 2017 at 18:44
  • $\begingroup$ Larry niven messes with this idea, jinxian are human that live on a heavy world and look a lot like fantasy dwarves and are freakishly strong when they travel, they also die young from heart failure and infarctions, since they have cronic extremely high blood pressure $\endgroup$
    – John
    Commented Jun 22, 2017 at 21:30

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