500 million years ago

Origin of intelligence and mental illness linked to ancient genetic accident

How humans --- and other mammals --- have evolved to have intelligence

December 4, 2012

Like mice, humans with mutations in the DLG2 gene made significantly more errors than healthy control subjects in tests of visual discrimination acquisition and cognitive flexibility (credit: J. Nithianantharajah et al/Nature Neuroscience)

Researchers have identified the moment in history when the genes that enabled us to think and reason evolved.

This point 500 million years ago provided our ability to learn complex skills, analyze situations and have flexibility in the way in which we think.

According to Professor Seth Grant of the University of Edinburgh, who led the research, intelligence in humans developed as the result of an increase in the number of brain genes in our evolutionary ancestors: a simple invertebrate animal living in the sea 500 million years ago experienced a “genetic accident,” which resulted in extra copies of these genes being made.

Mice and humans share limitations of higher mental functions’