An analysis of data on the four million fathers and children of Northern Europe who lived in the 17th and 19th centuries dispelled the widespread notion that late paternity and the survival of all children in modern developed societies contribute to the accumulation of dangerous mutations and harm the general health of the population. The study is featured in the bioArxiv preprint journal and briefly reported by New Scientist.
Many biologists believe that evolution has stopped in developed countries, as almost all children live to adulthood - and medicine no longer allows nature to select naturally. However, German psychologist Ruben Arslan and his colleagues have found evidence that evolution is still ongoing, and harmful mutations are being removed from the population.
Arslan picked up the records in church books about the birth and death of people in Germany, Sweden, and the province of Quebec - and compared them with modern Swedish medical statistics. Previous studies have shown that each extra year of a father's life (before conception) adds about two additional mutations to his child (at the gene level). However, Arslan found that these mutations are less likely to go further: in later children, their offspring are less born (by about 5 percent).
The reason for this is that extra mutations make it more difficult to conceive and have healthy children. In addition, scientists have found that although in the twentieth century the age at which men have their first child has grown greatly, the average age of fathers in the population is now lower than in the sixteenth century.