Scientists have discovered a new way to determine the average age at which males and females consistently reproduce evolutionary history of mankind.
By studying DNA mutations in modern humans, they uncovered a window that let them see 250,000 years into the past.
“Through our research on modern humans, we found that we can predict the age at which people have children based on the types of DNA mutations they inherited from their children.” says Study coauthor Matthew Hahn, a genomics scientist at Indiana University Bloomington.
“We then applied this model to our human ancestors to determine at what age our ancestors reproduced.”
They found that over the past 250,000 years, the average age for human children was 26.9 years. (For context, 300,000 years ago is also roughly when our species first appeared.)
The average homo sapien Father has always been older than average homo sapien Mother, according to the study, with men become parents at 30.7 years versus 23.2 years for women.
But the age gap has shrunk over the past 5,000 years, the researchers add, noting that the study’s most recent estimates point to the median age women become parents is now 28 years. This trend appears to be largely driven by women having children at older ages, they say.
Except for the last ones increase in maternal ageHowever, the study found a striking consistency in the average age of new parents throughout our species’ existence. It has not been steadily increasing since history, the team reports, although it has fluctuated over time.
The average age at conception appears to have dropped around 10,000 years ago, and since that would roughly coincide with the advent of agriculture and the dawn of civilization, the researchers say it may be related to the rapid population growth at the time.
Recorded history dates back only a few thousand years at best, and comprehensive population-level information such as this is difficult to extract from archaeological evidence.
but Secrets of our ancestors lurk in all of us today, and Hahn and his colleagues stumbled upon a way to determine the age of one’s parents so far back in time.
The new study takes up the discovery of de novo mutations – DNA changes that occur in a family member and occur spontaneously, rather than being inherited down the family tree.
While working on another project with these novel genetic changes and parents of known agesthe researchers noticed an interesting pattern. Based on data from thousands of children, the pattern and number of novel mutations that form in parents before they are passed on to their children depends on each parent’s age at conception.
This allowed researchers to estimate separate male and female generation times over 250,000 years.
“These mutations from the past accumulate with each generation and exist in humans today,” says Study co-author and Indiana University phylogeneticist Richard Wang.
“We can now identify these mutations, see how they differ between male and female parents and how they change depending on the age of the parents.”
Previous research has also used genetic cues to estimate generation lengths over time, but they typically relied on comparisons between modern DNA and ancient samples averaged across sexes and over the past 40,000 to 45,000 years, the researchers note .
“The history of human history is pieced together from a variety of sources: written records, archaeological finds, fossils, etc.,” Wang said says.
“Our genomes, the DNA found in each of our cells, provide a manuscript of sorts for human evolutionary history.
“The results of our genetic analysis confirm some things we knew from other sources, but also provide a deeper understanding of elderly demographics.”
The study was published in scientific advances.
