Sydney, August 2: Australian researchers at the Queensland Institute of Medical Research (QMIR) who conducted a DNA study, have reported that genes that are thought to have helped humans evolve big brains don't appear to play any role in how intelligent we are.
The Australian researchers tested 4395 teenagers for head size and intelligence and found that people who scored highly in intelligence tests didn't necessarily possess versions of the genes that were expected to code for big heads and intelligence.
And people who did possess the suspected 'smart' versions of the genes were not essentially the most intelligent or the ones with the biggest brains.
The team also studied genes ASPM, MCPH1 and CDK5RAP2, which regulate brain size and activity.
When mutated, these genes result in an abnormally small brain, a condition known as congenital microcephaly.
"Normal variation in these genes has not yet been investigated in relation to head size and intelligence," ABC quoted Dr Michelle Luciano, a researcher at QMIR as saying.
She says the only comparable previous study used MRI imaging to measure brain volume in relation to two microcephaly genes.
"Their findings [about a relation to brain size] were negative and they didn't find a relationship with two of the genes we were looking at. We decided to take it a step further and look at intelligence and lo and behold we find a similar negative result," she said.
Scientists have long believed that people with evolved versions of the gene would be smarter and have bigger heads, but were surprised to find this wasn't the case, Luciano said.
"We would predict that if you've got the more recent version you should have a higher IQ. We actually found that not to be the case. It is unlikely then that selective pressure for these genes is related to the evolution of intelligence in humans," she added.
Rather, she says the genes might be important for a neurological function outside the brain.
Professor Colin Groves, an expert in human evolution from the Australian National University, says that, while brain size appears to be related to intelligence between species, this doesn't seem to be the case within a species
And despite the development of technological advances, he says there's no evidence that Homo sapiens has become more intelligent in the last 50,000 years. (ANI)