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:
- 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;
- 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);
- 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);
- 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);
- They have a higher risk for osteoporosis, type 2 diabetes, and noninfectious cancer, but a lower risk for senile dementia, and noninfectious cardiovascular disease;
- 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);
- 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);
- They are as solitary as orangutans;
- They are excellent swimmers, but relatively poor climbers;
- They have green pigments, blue pigments, and red pigments.
Given these characteristics, what evolutionary pressures would lead to Homo autisticus?