Fathers are 250,000 years older than mothers, according to research: ScienceAlert
Scientists have discovered a new way to determine the average age at which men and women reproduced human evolutionary history.
By studying DNA mutations in modern humans, they discovered a window through which they could see back in time 250,000 years.
“Through our research on modern humans, we found that we could predict the age at which people had children based on the types of DNA mutations they passed on to their children,” say study co-author Matthew Hahn, a genomicist at Indiana University Bloomington.
“We then applied this model to our human ancestors to determine what age our ancestors reproduced.”
They found that over the past 250,000 years, the average age at which people have children is 26.9 years. (In context, 300,000 years ago is also about when our species first appeared.)
The average homo sapiens father has always been older than average homo sapiens mother, the study found, with men who become parents at 30.7 years old, compared to 23.2 years for females.
But the age gap has narrowed over the past 5,000 years, the researchers add, noting that the study’s most recent estimates suggest the average age when women become parents is now 28 years old. This trend appears to be driven largely by women having children at an older age, they suggest.
Apart from the recent increase in maternal agehowever, the study found remarkable consistency in the average age of new parents throughout our species’ existence. It hasn’t increased steadily since prehistoric times, the team reports, though it has fluctuated over time.
The average age at conception appears to have dropped about 10,000 years ago, and since that roughly coincides with the advent of agriculture and the beginning of civilization, the researchers say it may be related to the rapid population growth at that time.
Recorded history goes back only a few thousand years at best, and broad population-level information such as this is difficult to obtain from archaeological evidence alone.
But secrets of our ancestors lurk in each of us today, too, and so Hahn and his colleagues stumbled upon a way to determine the age of parents so far back in time.
The new study capitalizes on the discovery about de novo mutations — DNA changes that debut in one family member and appear spontaneously rather than being inherited through the family tree.
While working on another project involving them new genetic changes and parents of known agesthe researchers noticed an interesting pattern. Based on data from thousands of children, the pattern and number of new mutations that form in parents before they are passed on to their children depend on each parent’s age at conception.
This allowed the researchers to estimate separate male and female generation times over 250,000 years.
“These past mutations accumulate with each generation and exist in humans today,” say study co-author and Indiana University phylogenetic Richard Wang.
“We can now identify these mutations, see how they differ between male and female parents and how they change as a function of parental age.”
Previous research has also used genetic clues to estimate generation length over time, but it was mostly based on comparisons between modern DNA and ancient samples averaged across genera and over the past 40,000 to 45,000 years, the researchers note. .
“The story of human history is composed of a diverse set of sources: written records, archaeological finds, fossils, etc.,” Wang say.
“Our genomes, the DNA found in each of our cells, provide a kind of manuscript of human evolutionary history.
“The findings of our genetic analysis confirm some things we knew from other sources, but also provide a better understanding of the demographics of ancient people.”
The study is published in Scientific progress.
#Fathers #years #older #mothers #research #ScienceAlert