Read (and watched) 'After Earth', where humanity has fled a dying Earth to colonise a new world. Unfortunately, for whatever reason, some intelligent aliens decide to periodically send waves of bioengineered monsters 'bred specifically for killing humans' (https://afterearth.fandom.com/wiki/Ursa).

Bypassing the story plot-wise, these monsters seem horribly inefficient, and don't make a lot of sense biologically. So I was wondering how an organism (barring bioweapons) could be designed to specifically exploit human weaknesses?


closed as primarily opinion-based by Hoyle's ghost, Cyn, JBH, Arkenstein XII, kingledion Apr 15 at 0:32

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Welcome to the site Luca, please take the tour and read up in our help centre about how we work: How to Ask, then read the general gudelines: help center . At the moment your question is both too broad and opinion based to fit with the way we work. You would need to edit it to reflect an answerable question that can have a single best answer. $\endgroup$ – Hoyle's ghost Apr 14 at 13:09
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    $\begingroup$ Make a smarter human. Who do you think offed them neanderthals? $\endgroup$ – Renan Apr 14 at 13:39
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    $\begingroup$ @Renan Neanderthals lived alongside humans for generations (2-5K years). We could even argue they didn't die out, they just got outbred. People of European ancestry tend to be about 3% Neanderthal. Though, if Luca allows enough time for the conquest, that method would certainly work. And it does exploit what some might call human beings' greatest weakness (sex). $\endgroup$ – Cyn Apr 14 at 14:55
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    $\begingroup$ When reading the answers here, you might want to consider some of the points raised in answers to my almost five years old question How would societal development be impacted if humans were not an apex predator? $\endgroup$ – a CVn Apr 14 at 15:33
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    $\begingroup$ What human weaknesses, specifically? Unless said creature is more cognitively capable than humanity (simplistically, "smarter"), humanity will always overcome them. As we have all comers to date. It's our ability to analyze the problem and develop tools to solve it that makes us formidable. So, if you could clarify, are we talking about a bunch of average high school students? Survivalists? Military? Politicians (you can kill all those you want, btw)? I can't think of any weakness that a predator could consistently exploit long-term. $\endgroup$ – JBH Apr 14 at 17:54

Humans are extremely efficient predators themselves, so trying to bioengineer apex predators to hunt humans isn't going to work well for you. Even in totally alien environments, such as underwater, humans have the know how to swim in shark infested water and come out alive and eating shark fin soup. About the only way for apex predators to prevail over humans is to catch individuals off guard or unprepared. A person falling overboard from a ship is far more likely to become shark bait than a prepared diver, and there are countless stories of people being attacked by predators while jogging oblivious with earphones in.

Trying to engineer alien apex predators might not work too well either, since the aliens are not adapted to the ecosystem. You can't replace lions on the Savannah with great white sharks and expect that to be effective.

I would go for something that humans would have difficulty defending against, fast, manouevreable, working at a different scale than humans so difficult to see, track or fight. My "go to" would be to bio engineer wasps so they become even more aggressive, amplify the deadliness of their venom and perhaps even take a page from Parasitoid wasp family and have them lay eggs in the humans to breed the next generation...

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It only takes one

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Worst case scenario

Humans would have difficulty discovering where all the wasp nests were, would also have difficulty fending off enraged swarms of stinging wasps, be killed or injured by the venom and ultimately killed by the larvae consuming the host from within. And while there are countermeasures for wasps and other insects, insects are very small and adaptable, capable of infiltrating even small cracks or holes in shelters or clothing, and breeding explosively so even small numbers can restock areas quickly. Humans will need to spend an inordinate amount of time "bug proofing" themselves and their shelters, which will negatively impact many other aspects of survival. So any alien looking to field a bioweapon to attack humans should consider bioengineering wasps for the task.

[]: https://i.stack.imgur.com/PhsAa.jpg


Set a thief to catch a thief.

If you want to know ways animals can kill naked people in the woods, there are many. A lone naked human is barely a match for a jackal. But as for our species generally, animals were no match for even our distant ancestors. We have many ways to compensate for biological weaknesses. That is why the most efficient killer of humans is humans. The intelligence, creativity and ferocity of humans is largely a result of millennia of intrahuman competition - and cooperation.

The nature of the engineered human depends on the tech level available. If you have guns, then small, resource-efficient humans would be best because you can have more of them and have them not starve. If it is earlier tech then a variety of sizes makes sense - large ones for your shock troops but not so many they eat all the food.

For purposes of fighting, most human weaknesses have been circumvented to some degree with tech. You can shield soft parts, cover soft feet, make fire to compensate for lack of fur, domesticate dogs to watch for you while you sleep. You can preserve and store food to compensate for how you are always hungry.

Ideas about how humans could be more efficient killers of non-self group humans.

  1. Target group humans are not acceptable as mates or slaves. Neanderthals were not wiped out, because they are us. There was only one way that could happen.

  2. Killer group humans cooperate flawlessly. The problem with fierce humans is that they turn on each other. Not your bred killers.

  3. Killer group killers don't kill their own kids! Don't kill the kids! Infant mortality at the hands of unrelated males (in present society read boyfriend, stepfather) is a big problem even today.

  4. A weakness of humans is that we need resources: food, water, fuel. Modern warfare goes after these resources without compunction but that is a more recent development. Pretechnological warfare spared resources that the victors would need for themselves - e.g. Deuteronomy 20:20

Only the trees which thou knowest that they be not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.

The human killers have no such compunction. They make scorched earth warfare. How they get away with it is a matter for the story. Maybe they can eat dirt.

  1. Focus. The humans killers are always coming back to the thought of killing their target humans. Real humans over history get tired, get hungry, get horny, get cold. They want to take some scalps and then rest up. Industrial type total war is a very recent development. Your human killers might be primitives but they have the total war focused mindset - it is all about killing, all the time.

  2. The biggest weakness of humans - we are noncombatant tiny kids for many years and weaklings for many years after that. Your human killer humans grow up very fast. At age 3 they might not be full grown but they are coordinated and capable.

I will have to read After Earth. I am not sure why technological savvy humans fighting hungry large carnivores don't just poison and trap them all, like we do. It does not sound like these things are ghosts, or live via photosynthesis.


The easiest would be to take a good predator and make it more clever than humans and fast reproducing - any large cat or dog would do.

We could also make some birds, rats or such enjoy human meat a lot and attack in large groups when they see a human exposed, scout out or create holes in the living quarters of humans, and so on. Cat-like intelligence would probably be enough to make them impossible to defend against.

If you want some more creativity in how they look, check out microscopic life forms. Big mouths with saw-like moving teeth able to put big holes into you and suck you dry. Beaks which suddenly expand to several meters length to kill you at a distance (and then suck you dry). Glue which makes you immobile and then starts to pre-digest you into a puddle for lapping up. And many more...

As to specific human weaknesses: That's our necks, our dependence on air, and, for slow deaths, our dependence on water. A mandible would be a perfect tool for cutting through a neck, or, if the person fights back, arms and legs first.


There is an existing human predator. The Leopard.

Forget lions and tigers, we are accidental prey for them. For the leopard however humans and other large primates are right smack in the middle of their prey profile.

My daughter is a Zookeeper of many years experience specialising in large carnivores. While she respects the danger all the large carnivores present she has often commented that leopards are the single species where she has most experienced feeling like a potential dinner.

They have a complete geographic range, equator to arctic. They are effective climbers, and as an ambush predator, have an explosive turn of initial speed.

Why have we out competed them? They do not operate in packs, and humans can out think them.


  • Add pack behaviour akin to the wolf

  • Increase intelligence

Running away, one of homo sap's most effective survival strategies, is no help now.


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