# Could a creature evolve a biological "bulletproof vest"?

A variety of Earth species have hard, more or less rigid shells covering parts of or their entire bodies as a defense against predators. These work to a varying degree depending on the specific predator's hunting style, but they don't really present much difficulty to human firearms.

Ignore for a second the pesky issue of exactly which gradual steps would lead up to something like this; let's just say that whatever evolutionary pressure is needed is present in the creature's environment. Here, I am interested in the observable end result, not really how we got there. (Though if you can give a brief description of how we got there, I won't vote your answer down for that reason.)

• Could a creature reasonably evolve something resembling a bullet-proof vest, as a part of its own body (that is, one or more layers that, taken together, are resistant to penetration by bullets), without invoking magic?
• If it could, then what would that "vest" be like? (More specific questions to get you started: What would be the properties of the material that makes up it? How would it appear if you were to touch it? Given these properties, could it help the individual in some other way? What would be its weaknesses?)

I'm looking for something that hopefully significantly reduces the risk of death from a (not necessarily point blank or perfect aim, but hit) round fired from a real world circa 1850-1900 human firearm that would be managable and usable by a single human with appropriate training.

• I'm thinking spider silk. Not sure if I can spin an answer out of it, but I will try later. Jan 14 '16 at 21:11
• Amusing story: independent.co.uk/news/world/americas/… Jan 14 '16 at 21:13
• I disagree with the "opinion-based" close vote on the question. Either a bulletproof substance can be naturally created from organic compounds or it cannot. Jan 14 '16 at 21:51
• @HDE226868 - I could easily fantasize about a creature which "naturally" evolves armor plating to rival that of tanks, that doesn't make it less plausible than the guy suggesting a creature naturally weave complex polymers into its hide, or the other answer suggesting calcium plating. Many existing, terran animals are somewhat "resistant" to bullets, it just depends on what you're shooting at them. What information can you bring forward to suggest that one answer is more likely to occur in nature than any of the others? What is the limit on what that creature must be able to withstand? Jan 14 '16 at 21:57
• Many real-world firearms from c. 1900 would have trouble stopping any large animal with reasonably thick skin. Big game hunters of this period had to invent very large caliber "elephant guns" to take down elephants, rhino etc. so imagine something like an elephant with keratin plates in it's hide and extra-thick bone in strategic places - that alone would probably be a good defence against all but the highest calibre weapons of the time. Jan 14 '16 at 22:52

Well, we have several animals that are semi-bullet proof.

There are many stories where bullets ricochet of the skulls of bears, even little black bears. Grizzlies have lots of stories where a bullet just pisses them off. Some of the black powder muzzle-loaders could barely break the hide, especially when they were thick with fat to absorb the impact.

Elephants have a gun named after them because they had to make one with enough umph to kill it. Though certain well placed shots of lesser guns can make killing shots, though they may take days to a week to do the final kill. Other large animals have similar resistance.

Now here's a small animal that has more protection than expected. A 9mm ricocheted off and hit someone else. (actually it was his mother-in-law) so he might have been practicing that one!

EDT: For those who keep downvoting this answer, I'll be more specific. The Grizzly bear is bulletproof to quite a few firearms, between it's thick hide and layers of fat, it's body can stop many small arms rounds. Many can't even penetrate the hide, much less all the fat underneath. This is one of the major parts of body armor, prevent/reduce penetration by spreading out the impact over a larger surface area. Most of the personal firearms in the requested time frame would have a hard time with grizzlies. Even today's high powered rifles can ricochet of the skull. So if we already have animals that are effectively wearing bulletproof armor, then the answer is "YES" to an evolved bulletproof vest.

• However, it did kill the 'dillo, so I don't think you can properly call the shell bullet-proof. Jan 15 '16 at 0:24
• Bulletproof does not mean it saves your life. It means it prevents penitration. Many early vests let the wearer die from impact. Jan 15 '16 at 0:32
• +1 Grizzly Bears: godless killing machines, nature's equivalent of a tank. Jan 15 '16 at 22:31
• This doesn't answer the question at all... it just says "we have animals now that are bulky enough that they're difficult to kill." Jan 15 '16 at 23:11
• @Wingman4l7 I think that answers the question directly: yes, a creature can evolve a biological “bulletproof vest”? as animals already have.
– DA.
Jan 16 '16 at 0:45

## Sure -- if their biology allows them to generate long chains of polymers.

Modern bulletproof vests (without hard ceramic plate inserts) are made of multiple layers of tightly woven synthetic fibers called aramids -- aromatic polyamides. They derive their strength from having multiple chemical bonds along the polymer chain, which are oriented along the axis of the fiber when it is drawn out. Some vests have their layers of fabric additionally coated in a resin. It should be noted that while such materials will stop bullets from penetrating, the force of the impact will often leave a "dent" below them (they're tested on clay dummies) -- which, in a real-world scenario, can often result in internal injuries like a broken rib or heavy bruising.

Silk is a well-known example of a naturally occurring polyamide, renowned for its tensile strength. Experiments with multiple layers of silk serving as bullet-resistant garments were done in the late 19th century, and they had some success in stopping low-velocity rounds. The most plausible construction I can think of would be for your creature to use spinnerets to encase themselves repeatedly in a cocoon, precisely woven in a geometric pattern found in nature, and finally setting the layers together with an excreted resin (possibly spread manually over & into the layers). The damage done to this material is not "spot"-repairable -- the integrity of the fibers and the weave are compromised -- so your creature would have to discard the entirety of the damaged layer via shedding, and rebuild fresh ones.

All of these characteristics point to some sort of insect biology -- convenient, as it's estimated they're 80% of the world's species (900,000+ different kinds) so there's plenty of room for such unusual evolutionary exploration while maintaining a reasonable suspension of disbelief.

• You might address this in edits to your answer, but can aramids be created naturally? I did a short bit of research, and what information I could find seemed to indicate that they can't. Jan 14 '16 at 21:54
• @HDE226868: Technically, no -- we've only got polyamides (silk), not aromatic polyamides... hopefully a minor detail that can be overlooked. ;) Jan 14 '16 at 22:18
• @Wingman4l7: Or only excreting the resin on non-joint areas, so you have hard 'vest' over the parts that don't flex and soft (but strong) silk webbing over the parts that do: much like modern body armour. Jan 15 '16 at 9:23
• I like this answer - it suggests a world where the only bulletproof animals are spiders! Jan 15 '16 at 16:40
• @DA.: With a bit more brainstorming, I could probably come up with a sort of "exoskeleton" type development of the bulletproof vest via a pupal stage. Jan 16 '16 at 0:51

The long answer is define bulletproof.

Soldiers wanted protection from bullets, so we developed bullet proof vests, and kevlar helmets.

Then we wanted the ability to kill enemy soldiers wearing bullet proof vests, so we developed armor-piercing rounds.

When the army wanted to improve the survivability of their troops - armor wearing or not - they started moving them in light-armored transports instead of trucks.

So the people who wanted to kill soldiers in light-armored vehicles developed better weaponry to do so, etc.

What I'm getting at here is that a creature may very well survive being shot by one caliber weapon, only to be defeated by a hunter with a bigger gun. And we can build bigger, better guns much faster than some animal could evolve better armor.

That doesn't mean that a creature couldn't shrug off some damage, from some weapons. Try killing a rhino or an elephant with a .22 rifle. But humanity has significantly stronger weapons than that at our disposal.

Funny (sort of) Story: In WW2 the standard issue Russian pistol was a .22 caliber. An alarming number of times the bullet fired from this pistol would fail to penetrate the standard issue German winter coat. So the Russians upgraded to a .22 Magnum. The Germans didn't "upgrade" their coats.

• That's why I specified some criteria for the firearms involved.
– user
Jan 14 '16 at 21:16
• And this is before we even get to the fact that bullet proof vests don't exist. They're bullet resistant vests. Light ones are good for a shot or two, heavier ones are rated to withstand 8 or so. They might take 9 or 10 before letting a shot penetrate, but that's a question of circumstance and random physics perturbations. Jan 14 '16 at 21:17
• @MichaelKjörling♦ - yes you did, but even in 1850 there were small caliber weapons, and large caliber ones. If your beast can shrug off a 7.62 round, i'll shoot it with a naval cannon, and then it'll die. What I'm saying is that humanity can always up the ante. Jan 14 '16 at 21:18
• I don't think this answer is correct given the criteria - yes you can up the ante all the way to nuclear weapons, but I don't think it can be said categorically that it's not possible for a creature to evolve some kind of armour that would resist the kind of firearms specified in the question. Jan 14 '16 at 22:38
• @AndreiROM "a real world circa 1850-1900 human firearm that would be usable by a single human", which excludes firearms based on technological developments since 1900 and also larger weapons of the period such as Gatling guns. Jan 15 '16 at 1:32

Yes - well, maybe.

Abalone armor is pretty tough.1 While not bulletproof, they're certainly strong, and comparable to some body armor designs currently used by humans (see Lin & Meyers (2005)).

Their shells are made from interlocking tiles of calcium carbonate, reminiscent of certain tiled arrangements for bulletproof vests (the ones made of ceramic). However, the tiles are arranged irregularly, in a way that makes it harder to penetrate them. They're bound together with a coating of protein "glue". Abalone armor could be mimicked to create new types of bulletproof vests, or the creatures could develop a stronger version of it.

So, I think that some sort of bulletproof armor is possible, if it is based on a system like this.

I'm aware that there's an ongoing debate in the paleontological community as to whether the armor of ankylosaurs and related dinosaurs was bulletproof. As far as I know, the evidence does not support or destroy the hypothesis that it was.

1 An abalone is a member of a family of sea snails.

In theory it would be possible for a creature to develop bullet proof armor for a fixed caliber round.

However, in practice it's not very likely. Nature will typically use a variety of short term strategies when dealing with high mortality:

• Go extinct: see buffalo. If you kill them faster than they can evolve.
• Reproduce faster. They generate more offspring than you remove by shooting them. Typically only an option for smaller animals, or animals that start small (like fish).
• Increase aggressivion: offense is the best defense. They kill/disable you before you kill them.
• Increase fear: you can't kill them if they run away fast enough.
• Camouflage: you can't kill what you can't find.

Only once we get to long term survival, will evolution have time enough to work it's magic. Even then it may not take an obvious direction:

• blood clotting and scarring evolved as a strategy to deal with wounds
• some animals can auto-amputate limbs and often even regrow them
• some animals have distributed neural systems (probably not possible for animals with a larger brain)
• Nice answer Leon. Welcome to the site. Jan 15 '16 at 14:44

I'm going to answer based on the assumption that the question is essentially asking:

Could an animal evolve biologically at pace fast enough to outpace technological evolution?

As several have pointed out, many animals were bullet "proof" at one point in history, only to be trumped by technological advances in firearms that render what protection they had useless against the increasingly improving technology.

So, in the context of the real world, I believe the answer is no, as biological evolution is simply slower than human invention. Going back to even cavemen era, humans were able to hunt animals much larger than themselves quite successfully.

One could argue that if it were possible, animals such as Elephants or American Bison would have already figured it out. :)

However, there's one major exception to the above logic that I can think of: bacteria. Granted, we're not talking about bullets here, as fighting bacteria with bullets is rather impractical. But if we consider the invention of anti-biotics as a medical "magic bullet" the above argument changes, as bacteria has been able to evolve faster than our technology. We humans are in a constant battle trying to fight bacteria as they, quite literally, do evolve anti-biotic resistances faster than we can wipe them out.

• Compelling meta-analysis of the question. +1 Jan 16 '16 at 1:03

# A: Absolutely

However, the main complication is minimum size. As others have implied, larger animals have a natural advantage over smaller animals, because all of their tissues are bigger, and must naturally be tougher to hold the animal together (as well as survive the normal bumps and scrapes that animals generally encounter). This is why you can't really hunt bears or elephants or buffalo with your typical 9mm street gat that you would use against hood thugs (with moderate effectiveness, no less).

Contrary to AndreiROM's answer, humans cannot simply build guns that kill arbitrarily tough targets. Man-portable weapons have an effective upper bound on size and firepower. At some point, the weapon either becomes too heavy for a single person to carry, or the recoil becomes too great for a human to safely fire the weapon.

For instance, one of most powerful rifles in the world today is the modern .50 caliber sniper rifle, like the Barret M82. Although the M107 is intended to be a shoulder-fired alternative, the fact of the matter is that most pictures of either rifle being operated involve the use of a bipod. This tells you that the weapon is pretty close to the edge of what should be considered "man-portable". Already, the M82 creates so much recoil that a muzzle brake is essentially required for safe operation. And yet, the muzzle brake itself increases the sound exposed to the shooter to well above safe hearing levels, requiring the use of ear protection.

# Lethal Ballistics

Most guns today are designed to kill animals, humans, or vehicles. Humans are pretty soft targets, so we can ignore those for now. Vehicles are hard targets, but they do not have good protection of vital organs, because that would make them heavier, more expensive, and difficult to maintain. Most animals which are hunted are smaller than moose. So the guns we have today are designed to kill animals that size or smaller.

What many non-hunters probably do not know is that it is easy to wound an animal without killing it. Shooting an animal from a bad angle or just grazing it has a good chance of missing vital organs. In this case, the animal has decent odds of survival, assuming it isn't tracked down and killed.

Designing a lethal gun/round is trickier than it might seem. You actually don't want a bullet to just fly through your target at high speed, because if it doesn't create a large exit wound and it doesn't hit vital organs, the target has a good chance of surviving. See this excellent article on the considerations involved.

# Summary

If the animal can get big enough, its size alone will produce a thick hide which will allow it to shrug off smaller rounds. I would hazard a guess that a brontosaurus would be pretty safe from most rounds being fired in 1850, except for lucky shots to vulnerable areas. But, supposing that you had a gun which could penetrate the hide easily, there is no guarantee that the bullet could reach vital organs or inflict sufficient damage to kill the animal. Humans are not knife-proof in the sense of having a hide so thick it can stop a blade, but the majority of knife attacks are not fatal.

I agree with Nathan that if the animal has a shaped carapace which tended to deflect projectiles, then it could significantly reduce or eliminate the lethality of many rounds.

Although you did not request a plausible evolutionary pathway to such a creature, it is not inconceivable to have an environment with regular ballistic hazards, from rocks being spewed by geologically active events (volcanoes, geysers, etc.) to predators that use a kind of high-speed attack to kill targets (think perhaps a hawk-like bird that uses its beak like a spear). Also, armor against bullets would generally be effective as armor against teeth, which is why creatures like the Ankylosaurus would exist in the first place.

I think it may be a mistake to ignore the environment to a larger degree. Life has evolved to handle immense pressures and temperatures, but not bullets - because there are no bullets in nature. If however, the environment contained objects with bullet-like potential, a very long slow evolution could indeed yield such results.

The what could be anything from 'unobtainum' micro-meteors raining down on the planet every few days (from comet-trails composed of such a material), through to a common defence mechanism of other life-forms on the planet. (Plants that have evolved to "shoot" spines using chemical reactions). The latter plants is in my opinion a better option, as an evolutionary "arms race" would occur between armoured-animals, and the plant-guns.

Many answers have centred on rapid-evolution, and I will state that I am certainly not. Evolution is rarely rapid in anything short of geological time-scales. @cobaltduck mentioned in the comments Spider-Silk, and this is a very good option.

Spider-Silk Body armour is a possibility!, Spiders obviously do not weave fibres, though they may cocoon prey. However given millions (if not billions) of years in an environment that demanded it, it could be very possible for a species to evolve specialised cells that lay strands of Spider-silk like material beneath the hardened skin/scales.

Another option that springs to mind is the Dragon Skin Body-Armour, using ceramic plates this man-made armour can stop AK-47 rounds at close range. While "baking" ceramics with strong composites is a intensive process for technology, Nature could (and would) find short cuts, depositing layers of material with specialised cells.

Again, I place my favour on this second option - while it has already been stated there is no such thing as "bullet-proof", Ceramic plates are pretty-damn close in modern warfare, Modern combat armour often includes such plates, capable of stopping most rounds (short of armour piercing). Specificity the gamer's Favourite the .50 calibre. Good technical research for this topic would be the Cells involved in Bone Creation, Osteoblasts and osteocytes these cells constantly dissolve bone-calcites and place fresh layers.

Something with thick scales or bony plates could shrug off small to medium caliber rounds, especially if they are at range or glancing.

A thick hide can stop a lot of rounds. The problem is that's the period where elephant guns were being developed, so a normal thick hide isn't going to do the trick.

If the creature had really hard, thick scales, then you'd have a lot more chance of stopping the round. The scales could be made of keratin, which is a what fingernails and lot of animal horns are made of, and if it was thick enough it could do the trick.

There's no such thing as bullet proof, only variations on bullet resistance.

The answer to your question comes in the form of a poem.

THE HIPPOPOTAMUS

I shoot the Hippopotamus
Because if I use leaden ones
his hide is sure to flatten 'em.

Conveniently the author of this lived at the time in question.

On a more serious note, you'll also want to look at the elephant gun and the fairly obvious reasons for its existence.

Evolution works much more slowly than weapon design, so while early weapons might not be powerful enough to punch through the hide of a large animal, the animal is not going to be able to evolve fast enough to counter the speed at which weapons are designed. In other words, no. An animal may initially be bullet proof, but it's not going to remain that way for long.

It could be plausible if you had crocodilians that had evolved stronger & thicker scaly structures in key areas.

They could have really strong hides supporting very hard scales, which would be big enough & positioned in a sort of array resembling some of those modern angular stealth surfaces, so that their 3D structure would encourage rounds to glance off from one surface to the other transferring momentum thru several deflections (especially helpful w/ the high caliber rounds I think were popular in your time period). These scales could grow in a way that developed internal tension, making them extremely strong & hard like prince rupert's drops. And they could have thicker skulls, & extra skeletal support for all their armor

Plus, keep in mind that crocodilians present a very narrow profile w/ their more vulnerable underbelly protected against gunfire by water or mud most of the time, so they'd be extremely well protected if they developed any kind of bullet-resistant scale structures

IRL, there's not been enough time/advantage for this to have evolved, but your world could include some feature to push it along. A significant body of water in a warm climate w/ gravel beaches & frequent tornadoes might be enough

As far as i know, big Galapagos turtles' armors are bulletproof - as Darwin mentioned in Origin of Species.

Considering this is fictional perhaps there's leeway for a creature from say 67million years ago. Ankylosaurus

• This is really more comment-sized than a full answer -- and in any case, that dinosaur was covered in HDE's answer. Jan 16 '16 at 0:01