Some breeds are genetically smarter

Long contemporaries have always suspected that body size and intelligence complement each other in a wonderful way. Now science is also presenting the corresponding evidence. In a large analysis, researchers show in the specialist journal Nature of this Thursday, why humans have become bigger and smarter in the course of evolution. Across the peoples and nations, the descendants tower above their ancestors and can usually also think more quickly what has been beneficial in human history up to now.

An international team of researchers led by Peter Joshi from the University of Edinburgh has analyzed data from more than 350,000 people around the globe. Not only weight and height were recorded, but also 16 characteristics which - if they deviate from the norm - can indicate the tendency to certain diseases. These include, for example, the values ​​for blood pressure, lipid metabolism and respiratory function, sugar metabolism and cognitive performance.

The analysis of the genetic makeup carried out at the same time revealed an amazing connection: the more genetically the parents differed from one another, the bigger and more intelligent the children became. Genetic closeness had the opposite effect. The descendants of first-degree cousins ​​remained an average of 1.2 centimeters shorter and had ten months less schooling than the descendants of unrelated parents.

From an evolutionary point of view, diversity is advantageous

Genetic diversity is seen as a great advantage in evolution. It has long been known that couples whose genetic makeup is very different have more robust offspring - the mixing of the various defenses equips them better against a greater variety of pathogens. The current results are to be understood in a similar way: With greater intelligence and body length, people whose ancestors are not related and who therefore have more diverse genetic makeup are "rewarded". Even if it is no longer so important in everyday office life, from an evolutionary point of view it means a survival advantage over enemies to be bigger and more intelligent.

"With our research we are getting to the bottom of one of the problems that Darwin raised when he asked about the benefits of genetic diversity," says Peter Joshi. "As a next step, we want to examine more closely which parts of the genome benefit most from this diversity." Contrary to what had been assumed, however, the researchers found no connection between lower genetic diversity and a tendency to heart disease, diabetes or other diseases.

In scientific studies, outstanding body size has often been associated with positive side effects. On average, taller people have better jobs and get higher salaries, they are seen as more attractive and relaxed partners who are also less jealous. Vertically disadvantaged contemporaries do not have to worry, however, in modern societies the evolutionary survival advantage is no longer quite as crucial.