In a satirical white drama/lighthearted tragedy (the opposite of black comedy/dark humour) science-fiction live-action film I am writing that takes place in 8991 of the Gregorian calendar, it has been some millenaries that Homo sapiens (or if you want to be pedant, hybrids between Homo sapiens, Homo rhodesiensis, Homo neanderthalensis, and Homo denisova) was replaced by Homo autisticus. The basis of my science-fiction movie is that humans have become less social and their metabolism has slowed down because of the worldwide resources that have become rarer (I am referring to the Holocene extinction also known as the sixth mass extinction). Some basic characteristics of my Homo autisticus include:

  1. They have an improved intrapersonal intelligence, an improved visual intelligence, an improved musical intelligence, and an improved naturalist intelligence, but a relatively poor interpersonal intelligence, and a relatively poor kinesthetic intelligence;
  2. They have a lower sexual dimorphism than their ancestors (females and males are the same size, males generally do not have facial hair, and they have higher voices than male Homo sapiens);
  3. Adults who do not suffer from gigantism or dwarfism and who are not overweight or underweight have a height between 1.32 metres to 2.08 metres (or 4 feet 4 inches to 6 feet 10 inches, if you want) (the worldwide average is 1.70 metres or 5 feet 7 inches), and a mass between 45 kilograms to 125 kilograms (or 99 pounds to 275 pounds if you want) (the worldwide average is 85 kilograms or 187 pounds);
  4. They are mesothermic (lukewarm blooded) (like great white sharks, tunas, and naked mole-rats), have a slow metabolism, and live on average 12 decades (120 years);
  5. They have a higher risk for osteoporosis, type 2 diabetes, and noninfectious cancer, but a lower risk for senile dementia, and noninfectious cardiovascular disease;
  6. They are less fertile than their ancestors (they have a lower twin birth rate, both females and males become infertile when old, but it happens on average only at 85 years old for females, and at 95 years old for males);
  7. They have an improved sense of hearing and smell (they can smell underwater like star-nosed moles), but a relatively poor sense of eyesight (technically, they are able to see ultraviolet, thanks to a mutation of the short-wave-sensitive opsin-1 gene, but most are myopic);
  8. They are as solitary as orangutans;
  9. They are excellent swimmers, but relatively poor climbers;
  10. They have green pigments, blue pigments, and red pigments.

Given these characteristics, what evolutionary pressures would lead to Homo autisticus?

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    $\begingroup$ You're making this a lot more complex than it needs to be. Autism runs in my family, and IMOHO it's a survival trait in an internet reality where immediate personal interaction is increasingly irrelevant. But given the dates, all you need is for them to be smarter, and they outcompete everyone else. Global systems mean they need other humans less on a personal basis. But massive genetic engineering will monkey-wrench this being natural evolution in a major GATTACA way. $\endgroup$
    – DWKraus
    Oct 3, 2021 at 21:08
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    $\begingroup$ Can autistic people breath underwater? I tried yesterday and got hot coffee all up my nose. $\endgroup$
    – Daron
    Oct 3, 2021 at 22:01
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    $\begingroup$ Why are you alluding to a real-life human diagnosis when designing a non-human species whose traits are not the same as autistic humans'? I think many autistic people would be unhappy to have their diagnosis reduced to 'less social' and confused to be associated with smelling underwater. I'm sure your story is lovely but I'd pick a different species name. $\endgroup$
    – dbmag9
    Oct 4, 2021 at 11:34
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    $\begingroup$ If you call this species "homo autisticus" then your writing is not going to age well; "poor interpersonal skills" and "solitary" are kind of a contemporary stereotype of autistic people that many non-autistic people today believe, but isn't really true. A better way of putting it is that non-autistic society has a lot of social rules that don't make sense, e.g. you're supposed to drop hints instead of just say things directly, you're supposed to touch people in some circumstances without asking, and so on; and autistic people don't follow these rules because they don't make sense. $\endgroup$
    – kaya3
    Oct 4, 2021 at 12:44
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    $\begingroup$ While I can't comment on the intent behind this idea, treating a medical or psychological condition as nothing more than the set of the clinical symptoms of such (much less the most offensively stereotypical ones) in a work of fiction seems to promote the idea of treating actual people with that condition similarly: as a set of traits, rather than actual people who live with that condition, who don't all have the same symptoms and who deal with those symptoms in various ways. The former treatment is deeply problematic. Although perhaps your actual story gives a fair representation. $\endgroup$
    – NotThatGuy
    Oct 4, 2021 at 13:31

2 Answers 2


Evolutionary bottleneck



Humans have been through an evolutionary bottleneck. The populace that lived through this bottleneck to found the new human population had the genes you describe. Those genes may or may not have had anything to do with the fact that the individuals carrying them made it through the bottleneck. Four lizards that found a new population on an island floated there on a log by luck, not because of some genetic ability to float on a log.

Thus you do not need to figure out circumstances that would select for your genes. You need to figure out circumstances that kill almost everyone else or prevent them from reproducing.

Perhaps the ancestors of homo autisticus, themselves interested in reproduction in a rather academic way, froze away their gametes. These gametes were stored in an unorthodox, triple failsafed way such that they were the only ones available to reconstitute the human race after a cosmic mishap rendered everyone infertile and so those gamete bankers founded the new human race.

One individual in particular froze away a lot of sperm. Really a lot. Way more than enough.

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    $\begingroup$ I remember the scene in Zombieland where the geeks are all inside playing World of Warcraft at home as the rest of the world dies in the zombie apocalypse. The MC is a mega-nerd, and is almost killed when he lets the pretty infected girl into his apartment. Yay for the survival advantages of social isolation! $\endgroup$
    – DWKraus
    Oct 3, 2021 at 22:58

A global famine spanning centuries might explain the slow metabolism. That might come from general ecological catastrophe due to... Well, due to how much we pollute today.

As for being anti-social, imagine COVID-19 does not go away for a few centuries too. All extroverts are driven mad and die. Autism becomes prevalent exactly for not requiring aglomeration to maintain some level of mental health.

All other traits help navigate the post apocalypse, i.e.: red, gren or blue skins are camouflage against mutants and killer robots.

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    $\begingroup$ My Autistic son thinks COVIDland is paradise - mandatory non-interaction! And even my introverted "normal" son is driven bonkers by isolation. $\endgroup$
    – DWKraus
    Oct 3, 2021 at 21:11

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