A person’s genome is the complete set of DNA instructions found in each of their cells. Geneticists can learn important facts about a person, and even about the long history of humanity, by studying human genomes. For example, a person’s genome contains information about how old their mother and father were when they were conceived. This is because, as humans age, they accumulate genetic mutations. The number and type of these mutations that a parent passes on to an offspring depend on the parent’s age when the child was conceived.
In 2023 a team of American geneticists published research findings in which they used such genetic knowledge to probe humanity’s distant past. They analyzed a database of two thousand five hundred genomes from people around the world. They used their analysis to reconstruct when various mutations emerged over the last two hundred and fifty thousand years of human evolution.
They found that, over this vast span of time, humans were, on average, about twenty six years old when they conceived children. But they also found a difference between the sexes. Men were, on average, about thirty one years old, while women were, on average, about twenty three years old.
This difference might be due to patterns of social organization. In patriarchal societies, for example, men, unlike women, need to accumulate status before they can become fathers. But, the researchers also found much variability across human groups from different parts of the world. Critics worry that mutations from other environmental sources could be misattributed to the age of the parents. Researchers hope that studying larger databases of genomes will help clarify such issues.