One of the largest studies concerning genetic diversity found that children born to parents who are more distantly related are likely to be taller and smarter than their peers.
Philip Oldfield, writing for The Guardian, reports that height and intelligence could be increasing as more people are marrying partners from parts of the world that are more distant.
The study, published in the journal Nature, centered on the genetic background and the health of over 350,000 persons from around 100 communities spread across four continents. It was discovered that the more distantly related a person’s parents were, the taller they were and the higher their cognitive test scores were, as well as the level of education they reached. Researchers did not find a link between genetic diversity and the risk of high blood pressure or cholesterol level, although these effects were previously suggested to exist.
“Most people would believe a diverse gene-pool is a good thing, but the discovery that height is associated with diversity wouldn’t have been foreseen,” said Nathan Richardson, head of molecular and cellular medicine at the Medical Research Council, which funded the study.
According to Dr Peter Joshi of the University of Edinburgh and a co-author of the paper, questions which were first brought up by Darwin concerning the benefits of genetic diversity were answered by their research. Next comes finding the particular parts of the genome that benefit diversity the most.
The scientists used genetic information to discover instances when people had inherited identical copies of genes from both mother and father, which indicates that their ancestors were related. The connection was then compared to 16 biomedical traits. Height, lung capacity, general cognitive ability, and educational level were the only traits which were mutually related with genetic diversity.
“A smarter prehistoric man would have a survival advantage, and we can of course imagine circumstances where the taller you are the better chance you have of surviving,” Jim Wilson, Reader in Population and Disease Genetics at the University of Edinburgh, and an author of the study, said.
Results from the study may have a part in explaining the “Flynn Effect,” which is the growth of intelligence from one generation to the next, a phenomenon which was first recorded in the 20th century. Increased education and better nutrition are most often seen as primary drivers, but genetic diversity could also play a small part.
Shauna Lehner, reporting for The Market Business, quotes Dr. Joshi:
“We’ve found that the genetics are associated quite robustly across populations, and although we tried to compensate for environmental factors, we think the genetic effects are real.”
Joshi continues by stating that he and his team believe that genetic diversity lessens the possibilities of inheriting defective copies of the same gene from both father and mother.
The study is interesting, says CBS News medical contributor Dr. David Agus, since the last century was the first 100 years where widespread mixed marriages were seen. That trend continues to increase. Scientists at the Pew Research Center add that in 2013, 12% of new marriages in the US took place between spouses of different races.