So I'm creating a world in which humans have a close sister species very similar to the Japanese Nekomimi seen in anime and manga. Eventually, the humans turn on Nekomimis, perceiving themselves as superior. I'm not concerned with how Nekomimis actually came to be (handwavium can apply here), but I would like them to behave fairly similarly to humans, but different enough that humans would eventually want to cast them out as outsiders - despite our love of cats as proven by the Internet.


I was wondering how their realistic biology could work, my current framework is that:

  • They have a tail extending out from roughly the equivalent area as on a cat.

  • Their ears are similar in style to a cat's, in that they turn to face sources of noise, rather than human ears that don't move and they only have one set of ears, unlike some depictions.

  • Any areas that would be fur (such as a tail) or hair (like our head hair) are the same colour.

  • They can eat the same food as humans and are omnivores.

I'm also looking for any ways that Nekomimis would be better suited to some jobs than humans due to their biological differences.

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    $\begingroup$ History of slavery shows us that extremely little is needed for one human to claim total dominance over another. And in many cases there is no such thing as slave being "better suited" for specific case. One reason why slaves might be used is that they are seen as expendable. $\endgroup$ – Euphoric Oct 18 '16 at 8:32
  • $\begingroup$ @Euphoric Maybe I wasn't clear enough that I wanted them to start out as equals before bringing in a discriminatory government, sorry about that $\endgroup$ – Gladiator Kittens Oct 18 '16 at 8:33
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    $\begingroup$ @HarryDavid Well, Horgan is talking about people seeing themselves as superior and IRL cats are owned by people. So slavery comes as natural outcome. And even if outright slavery is not the case, people seeing themselves as superior to other usually means those other having less rights than those who are superior. $\endgroup$ – Euphoric Oct 18 '16 at 8:38
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    $\begingroup$ Minor point but "neko" is the ordinary Japanese word for cat, as in housecat. It might be better to say "nekomusume", "catgirls", or "nekomimi" / "nekojin", "catpeople". (Most catpeople depicted in anime are attractive young females but I don't know whether the OP's scenario follows that convention.) $\endgroup$ – Lostinfrance Oct 18 '16 at 8:49
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    $\begingroup$ I hereby sincerely apologize for weebing (en.wikipedia.org/wiki/Japanophile) out on you, but i am quite sure you mean Nekomimi, not neko (which is japanese for... cat.). Edit: @Lostinfrance beat me to it :( $\endgroup$ – Andreas Heese Oct 18 '16 at 8:51

The term "Neko" in Japanese literally means simply "cat" without further elaboration and also has a slang sense to refer to the submissive partner in a homosexual relationship. So, you may want to think twice about using that term with the belief that it would be understood unambiguously to refer to a "furry" humanoid with cat-like aspects.

Unlike dogs which are omnivores like humans, cats are obligate carnivores and that fact has a lot to do with the reason that cats are less full domesticated than dogs and are instead more symbiotic with human historically than they are truly domesticated (at least until quite recently, cats cohabited with humans from about 9,000 years ago and just started to be kept as true pets in the Middle Ages). Unlike dogs, cats could be trusted to guard grain stores because they would eat the pests such as mice and rats, but would not eat the grain itself.

Also, dietary differences are such a classic cultural distinction even between humans (kosher, vegan, paleo, no beef in India, etc.) that it would be a shame to waste the obvious opportunity. Dietary differences are used to great atmospheric and plot effect, for example, in the webcomic Orange Marmalade (which is currently being made into a live-action TV production).

Cats and dogs often have mixed color schemes, but if mono-color does it for you or has aesthetic appeal, cool.

One animated series, RWBY, has a scene where a discriminated against furry recounts a historical battle in which humans tried to ambush them at night, but their superior night vision caused them to prevail. A tendency to be nocturnal has wide application. So does a natural hunting instinct and a good sense of smell. A sense of balance and a tail might be an edge in construction trades and work in tree removal and fruit harvesting.

Your Nekos might do well as sommeliers with an evening oriented lifestyle, a fine sense of smell and a tendency to want a pleasure-filled life fitting well with a career as a wine steward. And the "cat house" has also always been a term associated with a particular profession that tends towards the nocturnal.

In Keri Arthur's City of Light series, genetically engineered humans with werecat DNA and werecats are both stealthy warriors.

Another webcomic to look at for inspiration as it is inhabited entirely by furries is Replay.

A nocturnal lifestyle, a feline fetish for cleanliness and a subordinated position in society might also make a good fit for janitors/maids in the society.

A reputation for being lazy and anti-social and not team players could fit into the subordinated role in society piece. It could also lead to lower levels of educational success because of trouble staying on task in conventional educational settings as opposed to independent study.

Conventional wisdom has it that cats are more attuned to weather changes, earthquakes, and ghosts than humans.

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    $\begingroup$ @The Lone Devil. Thanks for correcting my typo in the name of RWBY. $\endgroup$ – ohwilleke Oct 18 '16 at 21:52

The tail thing is pretty easy. Humans already have a vestigial tail structure called the coccyx. No ape has a tail, but plenty of monkeys do so there are clearly latent genetics we can exploit in order for humans to grow a tail later in life. I'd suggest basing the tail on New World monkeys so it is prehensile, which is a much more useful adaptation (but not really cat-like). At any rate, extending the tip of the vertebral column and attaching some musculature to drive a tail is fairly trivial.

Rotating cat ears won't help you much with human skull shapes. The ears are on opposing sides of the head, rather than on the top, so you can't rotate them to get a stereoscopic auditory input. You CAN enlarge the pinna (outside of the ear) so your catpeople can hear better but only what is in front of them, they will have to rotate their head to pinpoint sounds. Trying to extend the human auditory canal up to the top of the head would be an extreme feat, and would distort the skull significantly. But you can boost human hearing into cat frequencies and increase the balancing functions of the inner ear, though on a bipedal organism I'm not sure it will help as much as with a quadruped.

Boosting hair growth to cat-like levels is simple enough (although we really can't increase the number of hair follicles [hair club for men's claims to the contrary :)]) but you will run into overheating issues and nasty funk from sweat. Furred animals don't sweat like humans. So catpeople will either have to operate in colder areas, douse themselves in water to provide evaporative cooling (this is one of the reasons cats lick themselves), or develop a long tongue for panting. Cats like a higher body temp than humans, but trying to do that would require a significant alteration is a lot of biological functions in a human. Another possibility is less fur over key areas, like the armpits and groin, to allow for some areas for sweating. Humans still have hair in those areas to RETAIN heat, but if you have a permanent fur coat the opposite situation could arise.

Hard to imagine situations where cat adaptations would help in ways that technology wouldn't. But if these cat people have superb balance (helped a bit by the tail) they could be high elevation construction workers, cleaners, etc. Anything where walking along narrow surfaces is required. Improved frequency hearing could be helpful in detecting victims buried under rubble/avalanches, maybe hearing signs of mechanical stress in machinery (?), and possibly operating in low light environments since they may have a very weak form of echolocation.

There are other cat attributes like the reflective cornea for improved low light vision, increased visual response to motion, and predatory instincts that could certainly cause some level of discomfort from humans around these cat-people (especially if they are aggressive). They could also be territorial and a bit anti-social, especially a dominant male towards other males. No need for whiskers since the human shoulders are far too broad to ever allow the body to slip in behind the head (I've heard whiskers are to let animals know if they can fit their body through a hole) and at any rate, bipeds don't lead with their head anymore, they use their hands.


You have a few realistic options:

Human with cat ears, but human shaped skull

This would cause the ears to be placed on the side of the head, an odd placement for "cat-like" ears, even if the ears are shaped the same as a cats. As most humans are still capable of moving their ears a little bit, you would simply need slightly more developed and perhaps better placed muscles in order to achieve the similar range of motion. (I wasn't able to move my ears when in elementary school until I met someone who could, and I actually spent a few months training myself until I could move my ears too. I still can to this day.)

Human with cat ears, minimally modified skull

Moving the ears to the top of the head, while otherwise retaining human characteristics, would require some alterations in brain shape, skull shape, and moving the connections between the ear and brain to the appropriate location. This may cause interesting side-effects.

Anthropomorphic Cat

This would start with the cat physiology, and modify it just enough to be a true humanoid, ala TMNT bio-energy points. One consideration would be the spine and pelvis. The spine in a cat has muscles running along the vertebrae, which allows for the incredible twisting motions cats usually display in mid-air, or when contortion-snuggling. If the pelvis was altered to be 'locking' like a humans, then they would have an easier time standing upright, however lose some flexibility. If it was not altered, then they retain the full flexibility, but would get tired of standing up for long periods of time. However, you would have the head and ears without any further alterations.


Tails shouldn't be too much of a stretch, either way. Humans are occasionally born with actual tails, a well documented phenomenon. The catch would be that a human tail wouldn't be very mobile, as it would lack the extra muscles alone the spine (and tail) that a cat has. Perhaps a hybrid musculature, or the anthro-cat style would work best.


Cats are "sprint-sleepers", a term which here means that they take short sleeps, interspersed by periods of wakefullness. During the day, the sleeping periods are longer, and the active periods are shorter. During the night, being nocturnal in general, they are mostly awake, with only short periods of rest or sleep. This would lend towards nocturnal jobs more than day jobs, unless said jobs are intermittent or sporadic in nature.

The reflective retina grants better low-light vision, though it can be used to spot them in the dark as well, again lending towards jobs during the night or low-light conditions.

Cat's claws allow them to climb up things easily, but not down, due to the shape and attachment points; hence the cat-stuck-in-the-tree stereotype. Jobs requiring climbing might be applicable, so long as there is an alternate method of getting down.

Acrobatics in general seem a good fit, and anything requiring flexibility, balance, and a lack of fear of heights.

It is true that the whiskers allow for a more precise sense of if an opening is large enough for the head or not, so underground work is also not out of the question.

Heightened sense of smell (at least compared to a standard human, due to the vestial vomeronasal organ in humans which is still fully developed in cats) is a possibility. This is also why cats will make that odd, almost hissing-looking face when they smell some things, so as to allow air to pass over said organ. Wine-tester, food-tester (poison-tester?), artificial-scent tester, air-tester, and so forth might all be possible positions.


A species like that would not evolve naturally alongside humans, because evolution does not produce homologies (similarities in form unrelated to function) in lineages that don’t share a common ancestry. The common ancestor of the hominins didn’t look like a cat, and therefore no hominid would coincidentally end up looking superficially like some completely different branch of the tree of life. Horizontal gene transfer (such as having cat genes spliced in by a retrovirus) doesn’t work from a hard-SF perspective either, because genes don’t work like Lego blocks.

If you want a hard-SF explanation for them, then the Nekomimi must have been genetically engineered, and that gives them a history that probably explains their social status. If, for example, they were originally created to be domestic servants and companions, that might explain why they are considered inferior, or if they were originally assassins, spies and infiltrators, why they are still feared, even if that was generations ago and most just want to lead normal lives now.

I don’t get the impression that scientific accuracy is a major concern for this story, so I wouldn’t suggest you take the more evolutionarily-plausible path of giving a human-like species atavistic monkey-like traits. A small number of humans really are born with atavistic tails! You said you were willing to handwave their looking like cat-people, though, so this doesn’t seem to be what you’re after.

If you want the Nekomimi to exist naturally on another planet with a hard-SF rationale, then I think you need to reveal that the true natural history of human beings is different than people thought back in the early 21st century. Think Larry Niven’s Protector, where homo erectus was really an alien species that depended on a Fruit of Knowledge to gain sapience, lost it on Earth, and all the apes are really their descendants. If both apes and felines are really descended from aliens and their pets, then maybe they do share a common ancestor, and the Nekomimi simply retained more of those ancestral traits. Any apparent similarities to humans are the result of a parallel process of neoteny, and therefore convergent evolution, not homologies. But it’s still more plausible they’d look like Kzinti than like people with cat ears: they would be just as related to chimps and gorillas as to humans.

If they have to have lived on the same planet for as long as anyone can remember, then maybe they all forgot they’re the descendants of a colony ship or an apocalypse. Or you could just say they evolved in different places on the same planet and handwave it. You should be able to get away with one handwave.


I'm not sure how you want your story/world to be, but skyrim seems to do a great job at creating a species based on cats.


The Khajiit are in the game traveling salesmen. They are also used as assassins:

In addition to standard elven strike teams, the Thalmor also employ Khajiit assassins when stealth is required.

If you enter the game you get a boost on your sneak skill. You could use this information to give your cat species a roguish lifestyle or personality etc. In the game they are a minority, facing racial slurs by inhabitants of cities in Skyrim.

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    $\begingroup$ The Khajiit were around long before Skyrim. They're a feature of the Elder Scrolls series as a whole, along with Argonians (lizard people) and the rest. $\endgroup$ – JAB Oct 18 '16 at 18:15
  • $\begingroup$ yeah, sorry. i meant the whole series of course. i just played skyrim so i only had this name in mind. $\endgroup$ – Fenrir Oct 18 '16 at 21:45

Since you like Japanese anime, all these questions were answered with some detail into the science factor in the anime Utawarerumono and its sequel. They did an amazing job. It could feasibly give you ideas to watch the series.

I can't count the number of anime I've seen that offer various explanations, such as the anime K where something happened in WWII that made it possible for a human to become a cat and switch back and forth between human and a neko, though a bit more supernatural than the scientific approach.

Similarly in other anime they use gods, or Kami, as a reliable explanation, since their cast of celestial deities are quite vast, both based on Shinto as well as Buddhism.

Also youkai - monsters or demons depending on the source you refer to - can explain the nekomimi and others like it.

If you just want the one species, you can stick to that, although I've seen multiple anime that have a plethora of anthropomorphic animals in human form. Shapeshifters could potentially also explain how these human-like beings came about. You'll find it in a lot of anime where these non-humans change their appearance or hide their appearance just enough to appear human, though when hungry or excited their ears and tails tend to show their emotion.

Although some may consider it more the realm of fan fiction than actual science fiction I wrote a story where a group of beings evolved on Earth alongside humans. I based them mostly off of stories of Youkai. I tend to love the Kitsune, more, but all of them are equally intriguing.

As to a plausible scientific reason... I'm not sure but you might be pushing the boundaries of "believable" a little unless you choose something along the lines of Utawareremono and make animal DNA a necessary evolutionary step in the continual existence of the human race, created by scientist of course.... in that case it would be the ones with animal like attributes who would be the next step in evolution, not humans. The humans, fearing being wiped out by this newly evolved lifeform, could still be afraid or cruel to those they deem different.

  • $\begingroup$ Welcome to Worldbuilding, Vani Joy! If you have a moment, please take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox useful. Here is a meta post on the culture and style of Worldbuilding.SE, just to help you understand our scope and methods, and how we do things here. Have fun! $\endgroup$ – Gryphon Aug 23 '18 at 1:45
  • $\begingroup$ I'm not sure I exactly understand what you mean here. The only part of this that seems to actually answer the question is "I'm not sure but you might be pushing the bounds of believable a little unless you choose something along the lines of Utawareremono and make animal DNA a necessary evolutionary step in the continual existence of the human race, created by scientist of course." I'm not entirely sure what this means. I'm going to flag this as Not An Answer, but if this is clarified, I'll retract the flag. $\endgroup$ – Gryphon Aug 23 '18 at 1:47
  • $\begingroup$ I was offering what I thought was helpful advice. A fellow anime enthusiast would understand. I'm not a scientist by any stretch of the imagination, but I thought they could glean the answers they sought by watching the anime I suggested. I don't understand what you don't understand. I thought someone who had watched the anime I listed would clearly understand my meaning. $\endgroup$ – Vani Joy Aug 23 '18 at 1:55
  • $\begingroup$ I understand that you are new here, and I apologize if my comment seemed hostile. However, on Worldbuilding SE, any and all information relevant to an answer should be included or summarized within the answer. If information from anime is mentioned in the answer, it should be at least summarized. $\endgroup$ – Gryphon Aug 23 '18 at 1:58
  • $\begingroup$ great, I suck at summaries! I'm dyslexic and can only give the information the best I can. I think my ability to summarize is broken. I'll try not to offer such long explanations in the future. $\endgroup$ – Vani Joy Aug 23 '18 at 2:01

Well, the differences you describe are largely cosmetic, so I can't see any immediate difference that could lead to occupational opportunities. The tail may help with balance, say acrobats or such. The ears might make them more alert to small sounds, which is potentially good for something like security, patrolling, hunting certain animals. Though, these aren't gamechangers for their species

If you have stuff like cat's eyes, these are great at adjusting quickly to light conditions, but they don't have great longevity compared to human eyes.

If you want to have stuff like transformation and magic associated with bakeneko, then that tends to exit the realm of biology. What you described so far seems fine.


If you don't want to do magical stuff, but want it to remain slightly more 'scientific', you could lean on a later hormone flux that would fire off a sleeping gene (or genetic defect possibly caused by historic genetic tampering for a variety of reasons) and cause the coccyx to lengthen, ears to migrate and grow pointy, hair to sprout, etc. It would be a long, painful process, I imagine, especially growing the tail, which the kid from India who had his removed noted.

With a hormonal or 'age period' introduce a variance of those who have experienced incomplete transformations of catlike appearance, (And, even those who went too far or cases of those no longer mentally entirely human) perhaps even making a 'Cat trait beauty standard' thus, if you fall within X lines you are considered 'superior' (If you tie it into a late teens, early twenties range, the sterotype of the unchanged, are viewed more as 'children', and treated with similar lack of trust or knowledge of children -so more pitiable than slave-like. In this case, though, those who have gone too far are treated like mental patients, institutionalized and hidden from public view, even if their exterior is too far, their minds could be in one piece.) If you don't want to make it a long, drawn out process and want BAM -KITTEH!- and want to justify a complete reworking of musculature, etc consider using a cocoon.


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