Scientists have found a new way to determine the average ages when men and women have expressed themselves throughout the history of human evolution.
By studying DNA changes in modern humans, they found windows that give them a peek back in time 250,000 years.
“Through our research on modern humans, we noticed that we could predict the age at which people left their children from the genes of their DNA mutations,” says study co-author Matthew Hahn, a genomicist at Indiana University Bloomington.
“So we used this example to our ancestors to find out at what age our ancestors were procreating.”
In the past 250,000 years they found that the average age for humans to have children was 26.9 years. (For context, that’s roughly 300,000 years ago, even when our species first appeared).
Average Homo sapien Father was always larger than average Homo sapien mother, the study found, with male parents 30.7 years, versus 23.2 years for women.
But the age gap has narrowed in the last 5,000 years, the researchers add, noting that the most recent estimates suggest the average age when women become parents is now 28 years old. This trend seems to be driven mostly by women who have children at older ages.
In addition to the relatively recent age at maternal birth, however, the study found remarkable consistency in the mean age of new parents throughout our species’ existence. The group reports that the prehistory did not grow steadily, although it fluctuated over time.
The average age of conception appears to have occurred about 10,000 years ago, which roughly coincides with the advent of agriculture and the dawn of civilization, which researchers say could be related to rapid population growth at the time.
Recorded history only goes back a few thousand years at best, and broad data on population levels such as this is difficult to glean from archaeological evidence alone.
But the secrets of our ancestors are also hidden in each of us today, and that’s how Hahn and his colleagues stumbled upon a way to determine the age of our parents so far back.
A new study captures the discovery of new mutations – DNA alterations that debut in one family member, appearing spontaneously rather than being inherited through the family tree.
While working on another project involving these new genetic changes and parents known for centuriesThe researchers noticed an interesting pattern. Based on data from thousands of children, the form and number of new mutations formed in parents before being passed on to their children depend on each parent’s age at conception.
The researchers estimate that the male and female generations are separated by 250,000 years.
“These changes from the past accumulate with every generation and exist in humans today,” says study co-author and Indiana University phylogeneticist Richard Wang.
“We can now identify these changes, see how they differ between parents and men and women, and how they change the role of the parent with age.”
Previous research has also used genetic clues to estimate generational length over time, but typically relied on comparisons between modern DNA and ancient samples that were averaged across sexes and spanned the past 40,000 to 45,000 years, researchers note.
“The history of human history is distinct from different sources: from written records, archaeological discoveries, fossils, etc.” Wang says.
“Our genome, the DNA found in each of our cells, provides a kind of manuscript of human evolutionary history.
“The findings from our genetic analysis confirm some of what we already knew, but also provide a broader understanding of ancient human demography.”
It was published by the studio Journal of Sciences.
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