Human intelligence: in your genes

In a world-first, an international research team has provided the first direct biological evidence for a genetic contribution to people’s intelligence.

Professor Peter Visscher, lead researcher from the Queensland Institute of Medical Research (QIMR), said the study found that up to half of the difference in intelligence between individuals is due to genetics.

“We have long known that your intelligence is highly familial, but the extent to which genetics and your environment contribute has long been debated,” Professor Visscher said.

“The team studied two types of intelligence (vocabulary based tests and abstract, on-the-spot exercises) in more than 3,500 people and found that 40% to 50% of people’s differences in these abilities could be traced to genetic differences.

“We have shown the differing levels of intelligence in each person is the cumulative effect of many tiny changes in small sections of DNA across the entire genome.

“The impact of the individual changes are so minor that they were not detected in previous smaller genetic studies.

“This study is a start to understanding the relationship between people’s thinking skills and outcomes in life, such as health, income and lifespan. We are also interested in understanding why some people cognitively age better than others.”

The study examined over half a million genetic markers on every person in the study. The new findings were made possible using new techniques of analysis invented by Professor Visscher and his colleagues at QIMR.

Professor Visscher said that his study methods may hold implications for work and studies into the genetics of many complex diseases including asthma, diabetes and arthritis.

“While for this study we looked at the genetics of intelligence, we believe the risk for many complex diseases is the cumulative effect of lots of small genetic changes.

“Last year, my colleagues and I discovered that many common genetic variants together contribute to a person’s risk of developing schizophrenia, bipolar disorder and other common diseases.