Dads older than moms? Since the birth of Homo Sapiens – Corriere.it

Since the dawn of time the fathers have been older than the mothers, or rather since our species first emerged, over 250,000 years ago. This is suggested by research conducted by the team of Richard Wangan evolutionary geneticist from the University of Indiana in Bloomington (USA), published on Science Advances
. Previous estimates were limited to about 40,000 years ago.

The analysis of mutations

How did he and his colleagues, in the absence of documents, determine the ages of parents from generation to generation? By tracking down spontaneously occurring mutations in modern human DNA. All children have new mutations that their parents don’t have, a type of phenomenon we’ve come to know with viruses and genetic variants. These mutations they emerge when DNA is damaged before conception or occur due to random errors during cell division. Research suggests they are the older parents to pass on more mutations compared to younger parents.

The development of a software

So Wang and his colleagues initially conducted the study on a group of Icelanders (who have been sequencing the genome of all the island’s inhabitants for 25 years): using software, they analyzed data from a 2017 research carried out on about 1,500 Icelanders and their parents, who had monitored the age of conception and the genetic changes that occurred in 3 generations. The program learned to associate certain mutations and their frequencies with the age and gender of the parents.
Having developed the computer tool, the scientists applied it to the genomes of 2,500 modern people (taken worldwide), to identify mutations that have emerged at various times in human history. By dating when these mutations emerged, the team was able to map the average age of moms and dads over millennia.

The final results

The researchers found that 26.9 years was the overall mean age of conception in the last 250,000 years. But the breakdown by gender showed that the men they averaged about 30.7 years old when they conceived their first child, compared to 23.2 years of women. The numbers fluctuated over time, but the model suggested that men consistently had children later in life than women.
The older age of fathers can be explained biologically: Men are able to have children later in life than women, but it could be at play as well social factorssuch as the pressure on men in patriarchal societies to build status before becoming fathers.

The criticisms

Critics of the study say that the computer model does not take sufficient account of other factors (including environmental exposure) which may have played a role in the emergence of the mutations. Confidently reconstructing the age of conception across millennia will require sampling more populations, but this study, the authors argue, provides “reasonable estimates” that can help researchers gain insight into the lives of early humans.