Autism is linked to intelligence: People with 'smart genes' are more likely to have the disorder

• Yesterday, scientists announced that they had discovered 40 new 'smart genes'
• Their study found than many people with these genes were also autistic
• One gene called SHANK3, is a very good candidate for investigating a link

Researchers have found a surprising connection between intelligence and autism.

Yesterday, scientists announced the discovery of 40 new genes linked to human intelligence, and found that many people with the genes were also on the autistic spectrum. 

The findings could one day help shed light on the condition's origins. 

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The 40 new genes were discovered by researchers from the Centre for Neurogenomics and Cognitive Research in Amsterdam, based on a study of 78,000 people of European descent. 

'It is an outstanding article that provides the best evidence to date on identifying the genes that underlie human intelligence,' Bernard Crespi, a professor of evolutionary biology at Simon Fraser University who was not involved in the study, told MailOnline. 

'The findings should lead to exciting new insights into the neurological and developmental bases of human intelligence,' he said.

Most of the newly discovered gene variants linked to elevated IQ play a role in regulating cell development in the brain.

Computers have made it possible to scan and compare hundreds of thousands of genomes, matching tiny variations in DNA with diseases, body types or, in this case, native smarts.

The human genome has some 25,000 genes composed of more than three billion pairing of building-block molecules.

Many of the genetic variations linked with high IQ also correlated with other attributes: More years spent in school, bigger head size in infancy, tallness, and even success in kicking the tobacco habit.

One of the strongest - and most surprising - links was with autism.

Dr Danielle Posthuma, lead author of the study, told MailOnline: 'We found a positive genetic correlation between intelligence and autism, which suggests that genetic variants associated with higher intelligence are also associated with increase risk for autism.

'Of the specific genes we identified, SHANK3 is of note in this context, as it has been associated with autism several times and now also with intelligence.'  

This study only looked at European people, and the researchers believe that the findings could vary among different populations. 

Different gene variations are often important in different populations, and this could well be the case with intelligence. 

Speaking to MailOnline, Dr Posthuma said: 'Our findings apply to European populations, yet we do not know whether the same genetic variants are important in other populations as well.'

This isn't the first time that autism has been linked to intelligence. 

In 2015, researchers from the University of Edinburgh found a similar association. 

Almost 10,000 people living in Scotland had their DNA analysed, before being put through a series of intelligence tests. 

Those carrying genetic variants linked to autism had slightly better test scores on average than those who did not carry the autism genes.

In addition, further evidence of the association emerged when the same tests were carried out on 921 teenagers, who were taking part in an Australian twin study.

The nature of the relationship between autism and intelligence is not clear, said the researchers.

Although up to 70 per cent of people with autism have a mental disability, some individuals with the disorder can exhibit higher than average non-verbal intelligence.