Scientists have long wondered why autism disorders have not been eliminated through natural selection during evolution. A new study has shed light on this as expert found links autism genes might have been retained to make humans smarter.
Experts from Yale University looked into the data of 5,000 people with exceptional brains as well as autism spectrum disorders (ASD). The findings of the study were published in the journal PLOS Genetics.
In Charles Darwin's Theory of Evolution, gene variants that largely bring negative effects to humans' reproductive success are eliminated through natural selection. If the gene variants' advantages far outweigh its adverse effects, however, it can survive evolution. Scientists said this potentially explains why autism continue to exist from generation to generation.
Experts found out certain gene variants working to boost brain power and performance, such as the molecules needed to create new neurons to make humans smarter, are highly present among those with ASD. Its negative impact in the general human population, however, is small. Hence, this gene variant continues to survive natural selection.
"We found a strong positive signal that, along with autism spectrum disorder, these variants are also associated with intellectual achievement," research scientist Renato Polimanti said, per the Yale press release. "The idea is that during evolution these variants that have positive effects on cognitive function were selected, but at a cost - in this case, an increased risk of autism spectrum disorders," co-study author Joel Gelernter said.
Around the world, only one percent of the population have been diagnosed with ASD. In the U.S., its development risks occur in one in 68 births, according to Autism Speaks.
It's widely known that those with autism have superior abilities in mathematics, science, music or arts. People with ASD, however, have language disabilities or lack the social skills and the ability to process emotions.
