Nature v's Nurture
For decades, scientists, educators and psychologists have debated the contribution of our genes v's our environment to our intellectual functioning.
New research has quantified the contribution of both.
In a longitudinal study of almost 2,000 people, professors at the University of Edinburgh, University of Aberdeen and University of Queensland determined that genes are responsible for 40% of our lifetime intelligence, with the other 60% being determined by the environment.
The study commenced 80 years ago when intelligence tests were administered to almost all children born in Scotland in 1921 and 1936. Professor Deary from the University of Edinburgh tracked down 2,000 of these individuals who agreed to be re-tested and to supply gene samples for DNA analysis. They were aged from 65 to 79 years at the time of re-testing. Researchers examined the test scores and more than half a million genetic markers.
They found that intelligence was remarkably stable across the lifespan, but there were also examples of people whose functioning improved or worsened over time. The study of genetic
markers allowed Professor Deary, Professor Visscher and colleagues to create an estimate of to what extent genetic differences affect how intelligence changes across a lifetime.
While the outcomes show that both genes and environment play an important role in our intellectual functioning, genes are somewhat easier to study. Measuring detailed environmental factors is, according to Geneticist Professor Peter Visscher from the University of Queensland: "very very difficult". The researchers hope that this study will provide impetus for further research on the specific factors that are important for development of intelligence.
This research is critically important because intelligence is a predictor of many factors including lifespan, health and income. Understanding what influences our cognitive abilities may help us better manage conditions which affect the brain, such as dementia.
