Relevant 'breaking news' on the subject of monogamy:Fathered by the Mailman? It’s Mostly an Urban Legend
Five days a week, you can tune into “Paternity Court,” a television show featuring couples embroiled in disputes over fatherhood. It’s entertainment with a very old theme: Uncertainty over paternity goes back a long way in literature. Even Shakespeare and Chaucer cracked wise about cuckolds, who were often depicted wearing horns.
But in a number of recent studies, researchers have found that our obsession with cuckolded fathers is seriously overblown. A number of recent genetic studies challenge the notion that mistaken paternity is commonplace.
“It’s absolutely ridiculous,” said Maarten H.D. Larmuseau, a geneticist at the University of Leuven in Belgium who has led much of this new research.
The term cuckold traditionally refers to the husband of an adulteress, but Dr. Larmuseau and other researchers focus on those cases that produce a child, which scientists politely call “extra-pair paternity.”
Until the 20th century, it was difficult to prove that a particular man was the biological father of a particular child.
In 1304 a British husband went to court to dispute the paternity of his wife’s child, born while he was abroad for three years. Despite the obvious logistical challenges, the court rejected the husband’s objection.
“The privity between a man and his wife cannot be known,” the judge ruled.
Modern biology lifted the veil from this mystery, albeit slowly. In the early 1900s, researchers discovered that people have distinct blood types inherited from their parents.
In a 1943 lawsuit, Charlie Chaplin relied on blood-type testing to prove that he was not the father of the actress Joan Barry’s child. (The court refused to accept the evidence and forced Chaplin to pay child support anyway.)
It wasn’t until DNA sequencing emerged in the 1990s that paternity tests earned the legal system’s confidence. Labs were able to compare DNA markers in children to those of their purported fathers to see if they matched.
As the lab tests piled up, researchers collated the results and came to a startling conclusion: Ten percent to 30 percent of the tested men were not the biological fathers of their children.
Those figures were spread far and wide, ending up in many science books. But the problem with the lab data, Dr. Larmuseau said, was that it didn’t come from a random sample of people. The people who ordered the tests already had reason to doubt paternity.
Dr. Larmuseau and other scientists developed other methods to get an unbiased look at cuckoldry.
In a 2013 study, Dr. Larmuseau and his colleagues used Belgium’s detailed birth records to reconstruct large family genealogies reaching back four centuries. Then the scientists tracked down living male descendants and asked to sequence their Y chromosomes.
Y chromosomes are passed down in almost identical form from fathers to sons. Men who are related to the same male ancestor should also share his Y chromosome, providing that some unknown father didn’t introduce his own Y somewhere along the way.
Comparing the chromosomes of living related men, Dr. Larmuseau and his colleagues came up with a cuckoldry rate of less than 1 percent. Similar studies have generally produced the same low results in such countries as Spain, Italy and Germany, as well as agricultural villages in Mali.
The scientists got the same results after trying a different tack. They studied men in Flanders, a part of Belgium to which French people emigrated in the late 1500s.
The Y chromosomes in Flemish men with French surnames, the researchers found, had the same genetic markers found in men who live today in the region of France where their ancestors originated. Had there had been a lot of cuckoldry over the centuries, the link between genetics and surnames should have been weaker, or disappeared altogether.
In a commentary in Trends in Ecology and Evolution, Dr. Larmuseau and his colleagues argue that it’s long past time to toss out frequent cuckoldry as a myth. Studies relying on different methods in different cultures all point to cuckoldry rates of about 1 percent.
And because many of those studies are based on genealogies that reach back many generations, he argues, these rates must have been low for at least several centuries.
Beverly I. Strassmann, a University of Michigan anthropologist who gathered the data on paternity rates in Mali, agreed that widespread cuckoldry “was an urban legend. It seemed to have a life of its own.”
The evidence of low rates of cuckoldry comes not just from gene studies, she noted. In species where females mate with many males, the males tend to evolve sperm that are good at competing for fertilization. The males may produce large amounts of sperm, for example, and a high percentage swim well.
Humans, however, don’t rate in the sperm department.
“It’s of amazingly low quality,” Dr. Strassmann said. “Half the sperm can be duds; they can have two heads; they can be defective in all sorts of ways.”
The only way for men to have evolved comparatively ineffectual sperm, she added, was for them to have experienced high rates of paternity over time.
It’s not that widespread cuckoldry doesn’t exist in some cultures, Dr. Larmuseau said. Some South American tribes with high rates share a belief that more than one man can contribute to the formation of a fetus.
But Dr. Larmuseau suspects that these populations are the exception, not the rule. Humans have evolved to avoid cuckoldry, he said, because of our peculiar biology.
Human infants are born quite helpless, compared with the newborns of other animals, and they need a lot of food over a long period to fuel the growth of their calorie-hungry brains. Mothers needed fathers to help find the food.
“Babies really need good investment from the fathers,” Dr. Larmuseau said, “and the paternity has to be very sure in order for them to make those investments.”http://www.nytimes.com/2016/04/12/science/extra-marital-paternity-less-common-than-assumed-scientists-find.htm