I'm working on a story where the MC gets his body modified like Kamen Rider's. As such he becomes stronger than a normal human. But instead of being cyborg enhancements, they are biological modifications.

While not to the same levels as a Kamen Rider, how would one go about making a superhuman? As in one built for fighting, and can take punches, kicks, stabs, and other blows better than a normal human and is stronger than a normal human, while still being able to blend in with normal people, so nothing like kangaroo feet.

For example, such changes may include:

  1. A gastralia, similar to crocodiles or ancient dinosaurs, this modified human could have a ribcage extending down to his stomach, protecting it from any possible attacks.

  2. A more barrel-chest, similar to Neanderthals, who were much sturdier than modern humans, even being thought to survive charges from woolly rhinos, this modified human could have a bigger chest and larger shoulder blades.

  3. Possible "armor", through either Osteoderms or Keratin. These plates could exist either subdermally, appearing visually similar to callouses, or existing just above the skin, but thin enough that they can be easily hidden underneath a shirt or jacket, protecting him from punches, kicks, possible stabbing, and slashing attacks.

  4. With the inclusion of a gastralia, bigger shoulder blades, and a bigger chest could also allow muscles to grow bigger, or the attachment of new muscles. The gastralia could also possibly help with respiration, allowing him to regulate his breathing better than a normal human and have more endurance comparatively.

What other modifications would be possible while staying visually human?

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    $\begingroup$ None of your examples seems to be associated with "strength." Are you using this term loosely, or do you care about, say, the ability to dead lift a large mass? $\endgroup$
    – Cort Ammon
    Feb 26 at 1:34
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    $\begingroup$ Both, I'm using the term loosely as in tougher, but also as to mean strength. I changed the title to super-soldier, so as to avoid any more confusion. $\endgroup$ Feb 26 at 1:40
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    $\begingroup$ It's been done already in a book called Battle Circle $\endgroup$
    – Kilisi
    Feb 26 at 3:04
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    $\begingroup$ We're lenient with new users, but please keep in mind. (a) Offering your own answers and expecting more is prohibited in the help center and a reason to close questions. (b) We have hosted a LOT of questions about superhumans on this stack. Thus, there's a very high likelihood that your question could be closed as a duplicate of those others. Research is mandatory on Stack Exchange and searching past questions is part of that research. $\endgroup$
    – JBH
    Feb 26 at 15:33
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    $\begingroup$ A 2024 professional athlete is definetely superhuman compared to a 800's warrior. The modern athlete also needs a way more specific diet, exercises, and medical support. Baseline humans can get really powerful with the proper support - you don't need to meddle with their genes. $\endgroup$
    – Mermaker
    Feb 27 at 11:45

6 Answers 6


Whenever people start talking about super-soldiers, they often fail to realise the trade-offs that must be made. Without considering the difficulty of making any effective biological changes to humans, many of the changes that people propose would give an advantage in one area, but would have attendant disadvantages.

For example, human skin is relatively fragile, but allows for a great deal of cooling through evaporation. Toughening skin could go a long way toward resisting damage, but at the cost of reduced cooling capacity and sensitivity.

Muscles may be able to be modified to have greater strength per volume and mass, but if they also generated more heat, then compromising cooling by modifying the skin would result in more rapid heat stress.

We could modify humans to have more rapid neural conduction, but at the risk that the altered timings would render the brain non-functional. This might not be the case if the super-soldier was grown from a zygote, but then we start running into the ethical problems of breeding a soldier caste or species. An adult human whose nerve conduction times were altered would almost certainly end up in a vegetative state... or dead.

Then, if we manage to build a better human soldier, how much better are they? Better enough that it's worth the cost of trying to enhance them? Better enough that you can also deal with the post-war complication of what to do with leftover super-soldiers who aren't so human any more... or at all? That seems unlikely.

Super-soldiers are realistically so impractical that they're really the domain of trashy science fiction... That's not to say that trashy science fiction can't be enjoyable, as long as you can get picky buggers like me to suspend disbelief.

Realistically, you'd be better off spending all that money dedicated to obtaining better soldiers to developing combat automata. They can be designed from the ground-up to have capabilities that you can't give a human without their not being human any more, and they won't complain about human rights violations, since they will only have the brains to do their job and no more. If damaged, they can be easily repaired or replaced with off-the-shelf parts, while humans take time to grow and heal.

Hell... if you want something that looks human to be able to fight well, build a terminator. They're a good idea for a lot of good reasons.

  • $\begingroup$ Considering how much improvement even some “simple” growth hormones or other drugs can give you, I’d expect quite some room for improvement. Especially if the enhanced human isn’t limited by food/nutrients. $\endgroup$
    – Michael
    Feb 26 at 12:55
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    $\begingroup$ @Michael Except the problem is all the time and money spent producing said soldier could be better spent buying a buttload of cheap kamikaze drone / slaughter bots. $\endgroup$
    – Thorne
    Feb 26 at 22:29
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    $\begingroup$ @Michael There are trade-offs there too. HGH will increase muscle mass, but causes other health problems that you really don't want your soldiers having... and these days, increased muscle mass isn't as important as other factors that aren't so cheap to improve. $\endgroup$
    – Monty Wild
    Feb 27 at 0:56
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    $\begingroup$ @Michael Don't confuse improvements with tradeoffs. $\endgroup$
    – Mermaker
    Feb 27 at 12:04
  • $\begingroup$ This is way to negative. There are plenty of tiny improvements without relevant tradeoffs. Just being able to alter human into peak athlete form genetically, taking all these tiny alleles for better food metabolism, respiration, muscle growth and function. You will get someone who can regulate their temperature even in ice-cold water thanks to more active brown fat tissue, getting more oxygen from the atmosphere, and running kilometres before being tired. Add training and you have someone who can make important individual decisions on the battlefield and act on them. $\endgroup$
    – Colombo
    Feb 28 at 2:01

What is a super soldier these days?

Soldiers these days have guns so biologically, you're not going to be able to make them bullet proof to any real extent.

What you could do is improve eyesight and hearing, maybe some night vision, improved stamina, some improved strength but not to the point of bulking them up.

But does this make a good soldier?

Really the best genetic changes for a super soldier would be strong pack hierarchy mentality so they obey orders and fast breeding /maturation process so the ranks can be replaced quickly.

Spending millions of dollars on a single soldier is pointless when one lucky bullet could kill them in the first two minutes of a fight.

More soldiers is better than stronger soldiers.

  • $\begingroup$ I definitely see your point; but "more soldiers rather than stronger soldiers" only works for certain tactics. depending on the circumstances, it may be better for soldiers to be able to think strategically and be aware of their surroundings to a much greater degree than a.baseline human so as to not be shot in the "first two minutes of a fight." $\endgroup$
    – alkahest
    Feb 26 at 2:37
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    $\begingroup$ @alkahest Bullets travel at hypersonic speeds. Being aware often means keeping your head down. $\endgroup$
    – Thorne
    Feb 26 at 3:01

Amateurs talk strategy; professionals talk logistics.

What kind of fighting is your "super" human doing? That will affect the type of modifications that make a difference.

The Greeks and Romans raised citizen militias, so they got a good mix of people. The "ideal" soldier wasn't the one who was the most ripped. In fact, they considered overly-muscled warriors to be detrimental - all that muscle demands extra ration to maintain, and food was a major limiter to what an army could achieve.

Even in the realm of science fiction, "super soldiers" don't always work too well. Taura from Bujold's Labyrinth is an excellent example: 8 feet tall, extremely fast and strong, with fangs added on for good measure. And completely useless as a soldier because of the cost, dramatically reduced life span, and most importantly the absurd supply chains required to supply her with her caloric needs.

The best use of an individually deadly soldier - special forces - are also the worst conditions for getting regular resupplies.

An army marches on its stomach, and super-soldiers are soldiers with super-stomachs. Resistance to diseases, accelerated healing, and so on are going to be far more important.


Denser Bones.

This will work for your blunt-force attacks (kicking/Punching) - it won't 'stop' injuries, but it will make for considerable advantages.

Look at the over-success of peoples of Dutch and Polynesian origins in the likes of Rugby Dutch because they are on average big and tall and the Polynesians (Maori, Samoa, All Blacks, Fiji, Tonga and of course - all the loan players to other countries) are formidable because of this.

If you can make the bones significantly denser, you can drastically increase their ability to take a hit.

Also - Denser Bones means any strikes or attacks are inherently more damaging as they have more mass behind them. It also allows for more intense training (although there is an upper-limit where I think the Tendons give-way - sheering off the Bone - not 100% sure though)

Stabbing though - Stabbing represents a different challenge as it's a penetrating wound. The obvious solution is Stab-proof skin. Now - whether that's using a biological method (some kind of under-skin chitin layer - like a Crocadile scale) or it's using some form of implant - I'm not sure - but yeah - Bone Density and Stab-proof skin.

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    $\begingroup$ Except every modification also has downsides. Denser bones affects your buoyancy, stab proof skin means it's harder to treat medically. Being big isn't advantage to a soldier. It just means you're a bigger target. $\endgroup$
    – Thorne
    Feb 26 at 2:02
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    $\begingroup$ Denser bones carry less marrow, reducing immune response and blood production, where these are things you might want to enhance too. Is stab-proof skin as good at getting rid of waste heat as normal human skin? Osteoderms would reduce flexibility and increase weight. $\endgroup$
    – Monty Wild
    Feb 26 at 5:48
  • $\begingroup$ @Thorne - I mean Buoyancy is context dependent - if you look at the US Army Water proficiency - it's like a 50 metre swim and 3 minutes of treading water. Stab proof skin and medical issues - I see a point, but I think it could be countered. And I didn't say Bigger - just denser bones. $\endgroup$ Feb 26 at 6:14
  • $\begingroup$ @Thorne Increased bone density = increased weight which means the soldier is slower. The increase in weight would require an increased muscle mass which would even further weigh them down. In a sci-fi setting with guns and advanced material melee weapons your increased bulk would be more of a detriment than a benefit. Who cares how strong you are when a burst of gunfire will kill you at range. Also all that mass requires much more calories to keep running which strains your logistics. All that extra muscle needed for the dense bones? That makes more heat, which your thick skin would keep in $\endgroup$
    – Neberu
    Feb 26 at 19:34

I think you’ll like my mouthful-titled questions on this subject, the links to the other 8 are in the question:

Creating a scientifically semi-valid super-soldier, part 9: Temperature control


  • bird-like lung system. Helps improve your oxygen, but you’ll need a more rigid chest.
  • Spidersilk woven into the skin and hairs. Helps increase the toughness of the skin without destroying your heat exchange capabilities
  • multiple ear-holes in the ear, improving localization and letting you specialize the frequencies each earhole can hear
  • Improved mitochondria. Current Mitochondria can go much faster but don’t as you would overheat too quickly, smaller animals do use this faster feature. If your Mitochondria can alter their speed, and perhaps be more efficient, you have better control. You could go into hibernation or into supreme battle mode, leading to:
  • temperature control. You need to cool down and cool down fast if you are going superhuman. If your body can pressurize gasses and liquids beforehand and store it, then shove heat into them as they evaporate inside your body and are expelled it means you can get rid of a lot of heat compared to just sweating (which technically does the same thing but only on the surface of your body).
  • Liver islands surrounding your muscles. Your muscles are producing a lot of stuff that it dumps into the bloodstream to be altered by the liver and fed back to the muscles. But this is an inefficient process as the stuff your muscled need altering have to travel your body and might not end up at the liver and back at the muscles immediately. Creating groups of liver cells around muscles that process this and then feed it back using a lymphatic canule into the bloodstream in front of the muscle would speed up this process tremendously and help keep the muscles supplied with energy.
  • incompressible fluid lining the skin (not at the joints) could provide a healthy extra shock resistance.

There’s a bit more you can find in the questions and answers I made in the link. Things like how to handle bones (indestructible bones is a great way to kill your dudes, bones break at a certain point to absorb energy and save your more important organs). Or you could use distributed organs to improve your chances of surviving, no more “oh noes my liver got hurt now I’m dead!”.


With the standard objections in mind (see the other answers for those), let's see if we can't find some ways to beef up your super-soldiers.

Humans are actually pretty well optimized in a lot of ways, so this one isn't as straight-forward as you might think. There are some basic upgrades we can get away with that won't fall foul of the standard logistical and operational issues, but they won't necessarily qualify you as "super."

(For the purposes of this I'm going to be leaning heavily fiction. Not going to even try to justify these things in scientific terms.)

  • Sensory Upgrades

While electronics and gadgets are almost always going to be better than whatever meat upgrades you may be sporting, there are a few things that can make you far more effective without necessarily breaking you biologically.

First up, let's tweak the retinas to add a fourth cone type that is sensitive to mid-range infrared. The cone density can't change much so your color discrimination may be a little reduced, but being able to detect differences in temperature is useful enough.

Still in they eyes, a more effective structure of the iris to respond to light levels more rapidly and a nictitating membrane to protect against dust and such - well, it works for reptiles.

Next up, a bit of tinkering with the ear to increase the frequency range and sensitivity. Maybe optimize the ear itself to be a little better at directing sound waves so that our soldier has near-canine audio accuity. Let's add an actuator muscle to the Tragus while we're at it, so that your soldier has some way of reducing sound sensitivity at will.

I'd avoid modifying smell, taste or touch too much, except maybe to add some olfactory receptors for important chemical markers. We don't need a bomb dog, but being able to discriminate dangerous environments by smell seems useful.

  • Strength

Human muscles are strong enough, when fully utilized, to seriously damage themselves and the things they're attached to. You've all heard the stories about hysterical strength, women lifting cars off children and so on. The aftermath isn't pretty though: broken bones, ripped tendons, torn muscles. Nasty stuff. Electric shocks can do damage by causing muscles to spasm at levels much higher than you can normally sustain, ripping and tearing and breaking bones. Not fun.

Tendons - those little bits of collagen and elastin that connect muscles to bones - are pretty strong, but we could make them stronger. Lacing the tendons with other biological materials (lignins for instance) could significantly increase the connection strength, allowing higher muscle strength to be developed or utilized.

Similarly, skeletal muscles can be reinforced with stronger fibres to allow them to withstand greater stresses before tearing.

Strength comes at a cost however. The energy for every action comes from somewhere. That leads us to:

  • Energy Economy

Your whole body runs on supply and demand. Every muscle twitch - from the beat of your heart to the thousands of tiny muscle movements that allow me to type this - takes energy. Mostly that's means carbs and oxygen, although fast-twitch muscles aren't always aerobic. Either way you'll need damned good lungs and a robust circulatory system.

For lungs you'll want to work out how to increase the gas exchange efficiency as best you can, and maybe give them a bit more internal surface area to maximize the available oxygen absorption.

Circulation is a bit more difficult. You can't screw with the blood much, other than increasing the red-cell count a little, nor can you just pump more of it around without breaking a whole bunch of things. You can change the layout of a few things without breaking the whole, make the heart a bit more robust and maybe add some additional filtration in the liver and kidneys. Be careful not to over-pressure the brain though.

As for the fuel itself... improved liver function and better lipolysis pathways would be good. Maybe figure out how to get more efficient catabolism to produce all that ATP your muscles need.

  • Damage Resistance

Stopping bleeding is a big thing in trauma response. The body does an OK job of it, but large injuries are prone to leaking a lot. Would be nice if we could increase redundancy in the circulatory system and add some involuntary sphincter muscles to restrict blood flow in damaged areas.

We can add some modified adipoctes that store sticky material that helps seal things closed, from broken blood vessels to torn skin. Scarring might be significantly worse, but it beats all hell out of bleeding out.

That's after you get damaged of course.

Since we're already weaving lignins into other parts of the body, let's repeat that through all your subcutaneous tissues. That makes you a little harder to cut, but at the cost of a loss in flexibility. Shouldn't interfere with heat dissipation too much, but may over-insulate the muscles themselves. Be careful with this one.

And while we're at it, wrap bones in the stuff too. Add some rigidity and impact dispersal to the periosteum, protecting from impact breaks and the like. This should also strengthen the bone somewhat without having to change the bone structure, so you're not adding a lot of weight or reducing the marrow volume.

I'm sure we can come up with more along this line. It's a little bit sciency without being in any way actually realistic, but that's part of the fun of SF.


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