“The development of our intellectual abilities and the optimization of thousands of intelligence genes probably occurred in relatively non-verbal, dispersed groups of peoples before our ancestors emerged from Africa,” says the papers’ author, Dr. Gerald Crabtree, of Stanford University. In this environment, intelligence was critical for survival, and there was likely to be immense selective pressure acting on the genes required for intellectual development, leading to a peak in human intelligence.
From that point, it’s likely that we began to slowly lose ground. With the development of agriculture, came urbanization, which may have weakened the power of selection to weed out mutations leading to intellectual disabilities.
Now its a good point about mental disabilities. Just like people with physical disabilities, people with mental disabilities wouldn’t survive long in our hunter-gatherer times. Still another bigger question is “What is Intelligence”? People seem to immediately define intelligence to things our species hold dear. Visual and conceptual problem solving, or tool building. And in those things we’re pretty good. Still let’s look at this funny video for a wider insight:
A chimp is a essentially a human that needs to be institutionalized, if they were to be released in our society unfettered it would be downright dangerous. Still its interesting to think of what other animals can do. Some are simple mental processing from organs we don’t have, like sharks seeing the electrical signals of prey animals, or vipers seeing the heat signatures of their prey. Then there are things that we more-or-less have the same hardware, but not the software to handle it, like bats or whales and dolphins hunting and navigating by sound, or the countless animals that mostly perceive the world by smell over all other sensory inputs.
Sure we have TOOLS that can do all of those things, but its not like I could suddenly work the sonar array of a Los Angeles Class Submarine without extensive training, yet bats and Dolphins do it as soon as they’re old enough to go out on their own.
Overall if the Human population is continuing to grow, its all a result of “Intelligence”, given that humans aren’t surviving for our strength, speed, or our fangs or claws.
h/t Mrs. Weer’d