In an interesting new study, data scientists at the University of Indiana found that fathers have been consistently older than mothers throughout human evolutionary history, but that age gap has shrunk.
Researchers found that they could predict the age at which people had children from the types of DNA mutations they left to their children. Children’s DNA inherited from their parents contains roughly 25 to 75 new mutations, which allows scientists to compare the parents and offspring, and then to classify the kind of mutation that occurred. When looking at mutations in thousands of children, researchers noticed a pattern: The kinds of mutations that children get depend on the ages of the mother and the father. They were then able to apply this model to our human ancestors to determine what age our ancestors procreated.
Researchers determined that the average age that humans had children throughout the past 250,000 years is 26.9. Furthermore, fathers were consistently older, at 30.7 years on average, than mothers, at 23.2 years on average. But the age gap has shrunk in the past 5,000 years, with the study’s most recent estimates of maternal age averaging 26.4 years. The shrinking gap seems to largely be due to mothers having children at older ages.
“Our genomes, the DNA found in every one of our cells, offer a kind of manuscript of human evolutionary history,” explains Richard Wang, the lead author of the study and a postdoctoral fellow at Indiana University. “The findings from our genetic analysis confirm some things we knew from other sources, but also offer a richer understanding of the demography of ancient humans. These findings contribute to a better understanding of our shared history.”
The researchers said this work can help us understand the environmental challenges experienced by our ancestors and may also help us in predicting the effects of future environmental change on human societies.
The study, “Human Generation Times Across the Past 250,000 Years,” was published in the journal ScienceAdvances. It may be accessed here.