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Old 12-18-2016, 01:26 PM
Wesley Clark Wesley Clark is offline
Join Date: Aug 2003
Posts: 18,798
Humans share 99.9% of our DNA with each other, and that remaining 0.1% makes up about 50-80% of our IQ differences. IQ is mostly genetic, a genius chimp is dumber than an average human. Various factors can lower it like environmental toxins, isolation, abuse, stress, etc. but I don't think you can raise it much via environment alone (except for the Flynn effect, but I'm not sure if that is due to nutrition, environment or something else).

China has engaged in and I think now completed a program to find the genetic traits that lead to high IQ (which I think they got from taking DNA from thousands of people with an IQ of 160+ and looking for what genes kept coming up). I believe they found it wasn't one gene, it was thousands of minor variants each of which has a minor role in IQ. So they are hoping using this they can create smarter babies.

As to the physiology of the brain as it relates to IQ, I've heard it can be the fact that certain brain areas are wired together better in smarter people. Another is the neural efficiency hypothesis.

Also are you talking about IQ differences between Homo sapiens, or are you talking about IQ differences between homo sapiens and other species? Human brains have tripled in size in the last 2 million years, going from about 500cc to about 1400cc now. So brain size plays a role, however elephants and dolphins have larger brains with bigger neocortex areas.

Last edited by Wesley Clark; 12-18-2016 at 01:30 PM.