I'm looking for answers that focus on changes in internal anatomy that allow humans to survive in a high-g environment. If dramatic visible change can be avoided, that'd be great.

Circulatory: Blood is much harder to pull away from the ground. Energy needs to be delivered to muscles at a higher rate
Muscular: Muscles are under more stress due to lifting heavier loads
Skeletal: The skeleton need to support a load with 3x the weight

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    $\begingroup$ I think it's creepy that the first thing that comes to mind on this question is the need for multiple hearts... The Time Lords are real! $\endgroup$ Jul 8, 2017 at 23:15
  • $\begingroup$ @HenryTaylor If you're on a Doctor Who related approach, perhaps, upgrading them to Cybermen would solve all the problems. Cardiovascular pump chest units for circulation and biomechanical arms and legs to fix the muscle problems. This scaringly makes too much sense. $\endgroup$
    – a4android
    Jul 9, 2017 at 10:26
  • $\begingroup$ Not sure if pumping blood upwards would be that much more of a problem. After all, for every ounce of blood pumped upwards, (roughly) another ounce of blood will go down. Veins/arteries may have to become less flexible though, to make use of that effect... $\endgroup$
    – Till
    Aug 2, 2017 at 12:26
  • $\begingroup$ Would it be possible to spend all your time in a swimming pool? Living in an environment of equal density would help negate many of the issues of G $\endgroup$ Aug 3, 2017 at 12:08

1 Answer 1


The first thing to go would be posture. This whole standing upright would have to be reconsidered. After all, putting the most oxygen hungry organs in the body up at the top is asking a lot of our earth-born heart and veins. Completely prone would become everyone's preferred pose which might cause a sharp decline in personal productivity and mobility.

We would also have to give up salt. After all, who needs high blood pressure when your blood already ways three times as much as normal. Limiting dietary iron to induce anemia would become good medical advice for putting a little spring back in your day.

At least dieting would get easier. Loosing multiple pounds per week is easy when even the lightest broth feels like thick pea soup on the tongue. Pigging out on ten pounds of ice cream would still leave the gallon container half full.

Okay, so we aren't going to get very far on this planet in our current condition. Time for the genetic scientists to step in...

The name of the game is decentralization. Instead of relying on a single centralized pump, smaller fluid flow assistance organs should be spread out around the body. No major vein or artery should be run for more than a foot before reaching the next of these smaller hearts. In blood pathways which defy gravity, the hearts should be even closer together.

In later generations of the genetic manipulation, the entire idea of hearts and veins will be abandoned. Instead the blood passage ways would themselves be pumps. Every inch would be segmented with valves and lined with muscles such that no portion of the system simply holds blood. Every part contributes to the circulation of the body's blood supply.

Along with the enhanced plumbing, it would probably be wise to rearrange some of the systems. Eyes and ears don't weigh much so they can stay up at the top, but the brain could migrate downwards. Men have been accused for centuries that we keep our brains in our pants. Now in a very literal sense, that would be true of women as well.

We would want to keep the overall humanoid shape unchanged for aesthetics as well as to assist with dealing with other humans from other worlds. But we would not want to put anything heavy up in the head section with the ears and the eyes. So maybe just a cartilage shell containing helium. We are the airheads and proud of it!

Which leaves the bones and muscles... that is the tough part. It is sort of like building a muscle car. A bigger engine produces more power but it weighs more meaning it takes more power to move. The geneticists would have to work closely with material scientists. The age of all carbon and calcium would have to end. Light weight metals and silicon cording might replace the bones and tendons, allowing our current muscle mass or maybe even a little less to carry the load. If not, then we would have to plunder the animal kingdom for a muscle upgrade. Human muscle to strength ratios are abysmal compared to many animals...

"Scrap the Caddy, Clyde"

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    $\begingroup$ You make some great points about the bone and muscle structure and making the head lighter, but I don't agree with you about getting rid of the heart and lowering blood pressure. The problem for the circulatory system is moving the blood up, and the heart already doesn't have enough oomph to do that under 3g. Lowering blood pressure is lowering the pressure the blood pumps blood through blood vessels. I think the solution would be to raise the blood pressure by combining the heart with your pulsing veins and arteries. $\endgroup$
    – NeoBourne
    Jul 9, 2017 at 0:33
  • $\begingroup$ On the flipside, I don't think relocating the brain will be enough. The nervous system would likely need to be decentralized in the way you suggested for the circulatory system, with a denser, thicker, stiffer spinal column that helps with the posture problem and branches like the nervous system in a flatworm. $\endgroup$
    – NeoBourne
    Jul 9, 2017 at 0:47
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    $\begingroup$ Yeah, an increase in blood pressure is in order, in fact, not a decrease. That the salt thing? Muscles and nerves use those ions to fire. (The gated circulation to pump is a good idea which is already implemented in humans, so there's that.) $\endgroup$
    – The Nate
    Jul 9, 2017 at 6:06

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