Some of our ancestors were more robust than modern humans. Could they adapt to a 2-g world better than we might? Maybe even 3-g?

Over time their bodies could evolve, i.e. only the most robust would survive and reproduce. Perhaps they would become shorter, have heavier bones, a stronger heart and more robust artery function to keep up the blood pressure to their heads.

How long might evolution take? I'm thnking of the time when the Ice Age reduced the human population to thousands living in southern Africa; genetic diversity seemed to be enough at that time.


From an evolutionary perspective, we are not as "robust" as they were because we figured out that we didn't need to expend so much energy on that - there were other things we could spend our energy on which yielded better results.

A "protohuman" who's more "robust" is wasting energy carrying around all of that extra robustness. His current food consumption is based upon carrying all that around on Earth.

If he were suddenly in a 2g or 3g environment, he would immediately need more energy (food) to continue to carry around that robustness (perhaps he'd need a 4000 or 6000 Calorie diet).

Humans at our level would, before we went there, divert a lot of resources to exoskeleton enhancement (https://www.youtube.com/watch?v=-UpxsrlLbpU) which would let us adapt at our own pace. (Benefit of that video: Agent Coulson is in it).


Post humans could be adapted to these conditions pretty much by definition, since the central idea of "post humanism" is to use technology and biology to transcend our limitations.

Assuming that our far distant descendants are keen to settle on "Super Earths" rather than asteroids and comets in free space, there is no reason to suppose they will not tweak their genomes to thrive in these conditions. This won't be a trivial tweak, since bones and muscles need to be denser and stronger, the metabolic system will need to be adapted to provide more energy to the system without causing overheating of the core or brain (in fact, the metabolism might really be tweaked to run at a higher efficiency so the post human won't spend all their time eating). The other major tweak will be the respiratory system, to deal with the higher atmospheric pressure and different partial pressures of the various atmospheric gasses.

When you get right down to it, post humans will be adapted to every environment they choose to inhabit, so you will see various metabolic and physical tweaks, with various forms of technological augmentation added to the mix (my own feeling is post humans will spend most of the technological effort on the mind, nervous system and communications, leaving the biological augmentation for the "background activity" tasks they don't want to spend all their time thinking about). YMMV

  • 3
    $\begingroup$ He said proto human, not post human. They are our ancestors not our decendents. $\endgroup$
    – ozone
    Nov 1 '15 at 18:26
  • $\begingroup$ Trouble with reading the question too fast. Of course proto humans would much rather have be gathering nuts and berries right here on Earth than settling distant planets.... $\endgroup$
    – Thucydides
    Nov 1 '15 at 18:30
  • $\begingroup$ I read post human too, when I first saw it, but realized it was proto after I read the full question. $\endgroup$
    – ozone
    Nov 1 '15 at 18:41
  • $\begingroup$ This doesn't appear to be an answer to the question, because of the post-/proto- confusion issue. $\endgroup$
    – HDE 226868
    Nov 12 '15 at 2:28

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