So, I’ve been creating a world, or more alternate universe, where chimpanzees are the dominant species, and humans are just a wild animal. My four main characters end up in this reality, and most unfortunately, they crash land in a human hunting reserve. They are captured along with a large human colony, and taken to a research facility. The apes comment that the four look pretty weak and fat looking, and shouldn’t have survived in the wild. They then notice something very, very unusual. One of the humans, called Logan, is a ginger. He is very fair skinned, and has red colored hair. They immediately call the press, and try to get him to breed, in order to reintroduce his kind. Being ginger is supposed to be extremely rare in this universe, but I haven’t come up with a reason why. Their are about 140 million of them today, so I am asking: Why might being ginger be rarer in this universe?
I'm going to assume your chimpanzees are every bit as capable of nastiness as real humans are
Some species of animals are driven into endangered status or outright extinction by a combination of over-hunting and loss of habitat. These animals are usually targeted for quack medicine and other cultural practices, or as trophies that wealthy tourists from distant regions take home. Your chimps could do the same to humans in this world. Aperaham Huntington could be real proud of that stuffed redhead(the literal head of a redhead, cut off and preserved) on his mantelpiece. The tribesmen of rural Monkeyna Faso could believe that wearing a cloak made of ginger skin and hair blessed by their shamans makes them invincible. Ape-people in Orangutanistan might like to season their soup with gingers. And so on.
If you go with this route, IMO it's pretty important to add in a lucrative black market trade that often drives poor chimps and sometimes even park rangers to go after redheads. That would be a major driver of why gingers remain so rare in this world
Gingers could be valuable to modern chimp medicine. This can tie in with quack medicine as well. Maybe in the past raw ginger body parts was prescribed as a cure for a major disease, but what the chimp apothecaries and plague doctors didn't realise is that they could get the same results from non-redheaded humans as well. Fast forward in time, and GPs would routinely carry bottles of human extract. Big Chimp Pharma and/or State could see some scientific value in redheads as well. Their corporations could have snatched up redheads en masse for experimentation without concern for sustainability, due to lack of government regulation or with state complicity. Throw in corrupt officials for a nice tie in with the black market.
Gingers could be the new fad diet of your chimp world, like our power grains. Ginger production lines being unable to cope with a huge surge in demand would contribute to a mad scramble for free range or wild caught ginger parts across the first world nations. This could bring redheads to extinction or near enough. Sustainable practices by real humans are already tenuous enough as it is, maybe your chimps care even less than we do.
There are a combination of reasons that redheads might be nearly extinct in your universe. You shouldn't limit yourself to one either.
- It is a recessive gene (MC1R on chromosome 16 and possibly HCL2 on chromosome 4) which is just not expressed that much in the phenotype. You could delete those genes from your universe and just replace the gene with some made up variant such as GC1L as an example. If you run with this, you could even tweak whatever genetics you want to associate with the gene (like not dieing in the sun immediately or having the phenotype more rarely expressed)
- In your universe they could be sexually selected against. For whatever reason, they could be perceived as "bad luck" or bad breeding stock (in terms of genetic lottery of course but I don't think your humans would understand the concept). According to this, it's science...
- Consider a predator like a bear or some sort of bug/spider/creepy crawly parasite that goes for redheads. The Smithsonian wrote that certain mosquitoes are attracted to some people over others if you look at points 7(Clothing Color-> which we can substitute with hair color) and 8(Genetics). If you had a hungry predator or a disease ridden parasite with a taste for redheads, the population will drop quickly.
- Cultural What if your humans routinely sacrificed or took parts from redheads, therefor killing off a lot of them. I am reminded of this scene from GOT where the bandits try to kill Tyrion and chop off his "magic"...stick...
During the Middle Ages, a child with red hair was thought to be conceived through “unclean sex”- whether with the devil, or a little less precarious option, the milk man.
Hitler, apparently, banned the marriage of redheads to avoid the birth of defiant offspring, which of course (no comma needed) would inevitably lead to the overthrowing of his dictatorship
Ancient Egypt. It has been chronicled by scribes and then recounted by anthropologist James Frazer that if you were lucky enough to be born a redhead, and a man, you would be burnt alive, to honor and worship the god Osiris, and, of course, to help the corn crop ripen.
Sunburn and skin cancer
Because of their pale skin, gingers are very susceptible to sunburn. Sunburn leads to skin cancer. Thus gingers who are not protected by clothing from the sun die young and their children don't survive to adulthood.
Realize that in general without clothing and fire, humans would live in warmer climates than we do now. The Mediterranean, yes. Alaska, no. So feral humans would all be in more tropical or at least temperate zones. People who live in those areas have darker skin. It's probably not an accident that most gingers are from places like Ireland, which are much cooler and darker.
I realize that there are gingers living in tropical areas today. My point is that we have things like clothes, heat, and sunscreen that would not be available to feral humans. Humans were wearing clothes and making fires well before people migrated to cooler places like Ireland. Pale-skinned feral humans are likely to be rare, much as pale-furred chimpanzees are rare.
The other pale skinned humans may live as pets of the apes, who keep them indoors with the necessary heating. But it is much easier to get a new wild pet than to go to all the work of breeding. So more and more of even the pet humans become dark skinned.
The apes may even prefer tamed humans as being more interesting and stronger. Humans born in captivity may be too tame and boring. Observing the wilder behavior of humans born feral may be more interesting.
In this universe, red haired people have a problem surviving in the wild, and their population slowly going extinct.
On Earth, red hair is though to be due to a mutation which occurred 20-100 thousand years ago. Red hair and fair complexion is beneficial in high latitudes where Sun is weak and people can boost their vitamin metabolism due to lighter skin. However, close to equator, where prehistoric humans originated, red hair and fair complexion would be evolutionary disadvantageous, because skin needs to provide protection from UV rays.
So, in this universe people might have migrated to high latitudes at some point, where red hair mutation had started, but later, as apes took over, human population was restricted to tropical areas. Red head gene did not disappear right away, but its frequency has become much lower, which would make redhead people very unique.
Head hunting (literally)
I’m just gonna throw this into the mix, even though it’s my own question. I don’t like this answer as much, but maybe the apes hunt the humans foin their pelts, like we do it other animals. A nice red coat made of human hair could be a great accessory for the fancier woman(ape?) to wear. Hats, coats, jackets, mounted heads. A pale skinned, red haired human might make an interesting hunting story to tell. Since the ginger hair would be expensive, the gingers would likely be targeted for their trophy worthy dues. Again, I don’t loel this answer, as it wouldn’t be all that practical, as humans only grow a little bit of hair on their noggians, and it would take alt to hunt all the humans for one coat.