# Would humans from high gravity planets necessarily be super strong?

A common science fiction theme/notion is that humans raised on higher gravity planets would be super strong, shorter and bulkier than humans raised on normal gravity planets. Is this necessarily true? Would a person raised in 1.5X or 2X gravity environment be super strong relative to normal gravity humans?

They ought to be, assuming they’re approximately as strong as humans on their home planet. Imagine this: if a weight labelled “10 lbs.” on Earth weighs twenty pounds on Planet X (i.e. its gravity is twice as strong at the surface), then our “20 lbs.” weights will seem to be half as heavy as theirs. And so it will go with everything. If a human-X could lift 300 pounds on his home planet, he’ll be able to lift 600 here with the same amoung of effort.

Not for certain. You’re assuming that things would have the same mass both here and on this higher gravity planet, and that’s unlikely. Assuming this is a colonised planet, I imagine they’d have much lighter gear than what we’re used to in order to compensate. As so, the only “heavier” item they’d encounter on a regular basis would be their own bodies; so they would likely be more physically fit due to the more vigorous nature of walking, moving, and even just standing.

Depends on a number of factors. Like how many generations they’ve been on the planet. For the next several (hundred?) generations they will pretty much be the same humans genetically as Earth humans. That means they will have similar physical limits as to how strong they could even get. I don’t know that humans could survive on a 2G planet. Think about how well a 400 lb person gets around on this planet. I might just be fatigued all the time, even if I lived there since birth.

Lesser gravity, it might not be a big deal. Kind of like an athlete training at altitude.

Not really. If you’ve seen a 400 lb (240 kg) person try to get around, they do so with difficulty because biomechanically, their frame is not able move and support that kind of mass. However, someone at 50% or less of that weight will get around better because biomechanically, they are able to support that mass. Now, if you were to take someone from earth who had a supportable weight to a 2X g planet, they would be biomechanically stressed, but not in the same way a morbidly obese person would be on earth. Over time, they would learn to compensate, just as weightlifters are able to compensate by adding muscle bulk and bone density.

Once the Rull invasion, or nearby supernova cuts off the high grav colony from galactic civilzation, and they regress to feudalism, broken bones from minor falls will begin to take their evolutionary toll. After a few tens of generations of winnowing, only the strong boned will survive; at least that fraction of the strong boned that have the necessary musculature to cart around all the extra endoskelaton and are still quick enough to evade the native predators.

Why? It’s not like morbidly obese people suddenly become very heavy–it’s exactly the gradual sort of process that you’re describing.

Something that often gets overlooked is that on high-gravity planets, it’s not just how heavy everything is but how fast everything falls. Trip on a 2g planet, and in the blink of an eye you’re lying on the ground with broken bones. High gravity humans would need superhumanly fast reflexes as well as strength.

A little blurb about super man but it contains something relevant to this thread at the end.

How much gravity are we talking about? Do the humans in question have time to evolve to cope with the additional gravity?

Gravity in excess of 1G has a very real possibility of mutating the cellular structure of human beings over the course of generations. Note that absence of gravity has noticeable effects on our astronaughts and cosmonaughts when they return from a 60 day stint on the space station.

Its possible that heavier gravities over the course of several generations could yield an entirely new species that would not be human any more.

I, for one, welcome our new superchicken overlords…

The research Ive read regarding higher gravity and ‘super animals’ involves chickens and rats and other small animals.

These kinds of things dont necessarily scale up well with larger creatures, for the same reasons a 12 foot person isnt particularly viable, because theres efficiency limits with things like muscle, cartilage, bone etc - you cant just double the size and get double the strength.

Old age would be pretty rough as well I imagine, bad backs might take on a whole new meaning.

Otara

I think creatures that evolved on a high gravity planet would be short and squat, with strong bones. I believe Hal Clement wrote a series of stories (Mission of Gravity?) about a large planet that spun so fast that it had a large equatorial bulge making the force of gravity widely different at the equator from that at the poles. The creatures on the planet, who lived at the poles, were wormlike and when they traveled to the equatorial regions were very antsy about getting any weight at all very far off the ground.

Unless you do some kind of genetic engineering, the people will be genetically no different from any other group of humans that went through whatever screening process they used for choosing colonists. If they were from the top 10% in physical and mental tests, then the original colony would have those genetic characteristics and their offspring would probably have higher averages than the norm for the population left behind on Earth. It would take quite a few generations for any significant genetic changes relating to selection factors to change, but just like adaptations to altitude, I would expect to see developmental adaptations in the first generation.

Bone density and muscular development would probably be comparable to an Earth-normal athlete/weightlifter in top form. The average American male’s weight is around 80 kg. At twice Earth’s gravity, just walking around naked would be like carrying an extra 80 kg. Even some people who we would consider to be in decent shape can’t do squat exercises that are equal to their weight; heavyworlders would do that every time they got off the couch. Now imagine someone who could walk or even run significant distances while carrying an extra 100 kg or more.

The downside would be that they’d probably die at much earlier ages. There would be a lot more fatal accidents from normal activities and the injuries would be more severe even if they weren’t fatal. There would probably be more disorders related to fatigue and stress, and there would be more orthopedic injuries, even with colonists who grew up in the high-g environment. They’d have problems with their internal organs, especially their digestive systems. Women would have a harder time during pregnancy, and fetal development might be compromised. I’d expect to see a lot more miscarriages and infant mortality. Over time, of course, those would be mechanisms for genetic change, but I wouldn’t expect the first couple of generations to like it much.

(On preview, Lumpy beat me to it, darn it) . Something that a lot of those stories always gloss over is that it’s not just the person’s strength that would increase, they’d have to have faster reactions too. BotE calculations give me about 0.1 second difference for an object to fall 1 meter in 2 g gravity. One tenth of a second may not sound like much, but that’s a big difference when you consider that response time to visual stimulus is about 180-200 msec. In 2 gs, the object is on the ground before you even have time to react, but in 1 g you’ve still got a chance to try and catch it before it hits.

From birth, heavyworlders would have gotten used to things falling at a higher acceleration than us, and would have different reactions. Their reflexes would be no faster, due to no difference in their genetic heritage relative to Earth-normal people, but their responses would probably be much quicker. In 1 g, they’d overcorrect though, so they’d probably seem clumsy at first until they got used to the slightly slower falling acceleration and wonky trajectories of thrown objects relative to their experience.

Sorry for the double post, but I just found a story called Surviving 7G on Wired. It’s about hypergravity experiments NASA did for a possible Mars mission. The writer, Josh McHugh, actually participated in the experiment.

This is a problem, because their equipment would have to be stronger to withstand the double gravity.

Well, we do have lightweight, strong materials now- they’re just too expensive to be commonly used.

[Fred]
I’ll get the super=sauce!
[/Fred]

BUK BUK BUK BUGAWK!
You knew this job was dangerous when you took it Fred!!
carry on

Morbidly obese people aren’t just heavier than fit people - they find it difficult to move for a host of different reasons, some of which have more to do with bulk than weight.