Why you should care
Because what counts is surely the deeds, not just the seeds.
Let’s just say it: There is something that many of us take for granted as we celebrate our paterfamilias each Father’s Day — that the man we are giving the electronic tie rack or BBQ-scented cologne to is indeed our dad. I know, I know, not everyone’s father is their biological one, and what counts is surely the deeds, not just the seeds.
Still, all other things being equal, most of us would like to think we have at least some genetic material in common with the male animal who has been laboring for years under the vague supposition that, well, we have some genetic material in common. So for all of those living under the clouds of cuckoldry and uncertainty, we have some good news — and just in time for Father’s Day, too:
According to a recent survey published in Trends in Ecology & Evolution based on several recent studies, only 1 to 2 percent of children are actually the product of cuckoldry, or what researchers refer to as “extra-pair paternity.”
The cuckold — named for the cuckoo, that species of bird that notoriously lays its eggs in other birds’ nests — has long been a favorite subject of (largely male) writers and artists, from Chaucer to Shakespeare. But it wasn’t until the advent of DNA sequencing and more advanced paternity tests in the late 20th century that the extent of extra-pair paternity could begin to be quantified. And, for a while, it looked like human females might well be shopping around for good genes at an alarming (for some) frequency: The first lab studies suggested between 10 to 30 percent of men might be cuckolds. Such early estimates, however, came not from representative samples of fathers, says survey lead author, Maarten H.D. Larmuseau, a geneticist at the University of Leuven in Belgium, but from men who were tested because they already had some paternity uncertainty.
Over the past decade or so, Larmuseau and other researchers have set out, as the study’s authors write, to correct “the common urban myth … that many fathers are cuckolded into raising children that genetically are not their own.” And the new research has shown that cuckold rates in humans today hover around just 1 to 2 percent, and have done so across human societies for centuries. In a landmark 2013 study, Dr. Larmuseau and his colleagues combined centuries of Belgian birth records with DNA information from the Y chromosomes — passed down almost identically from father to son — of living men, and found a historical non-paternity rate of just 0.9 percent per generation. Such virtue is not uniquely Belgian: Larmuseau’s findings have since been replicated in studies in Italy, South Africa, Spain and even Mali.
Why are cuckolds relatively rare? There may be several factors at work, but it’s primarily because the costs of cheating and being caught are too high for women, the authors argue, “particularly in such a long-lived species as humans with heavy offspring dependence and massive parental investment.” Of course, even if cuckoldry rates have remained consistently low through recent human history, the question still remains as to whether humans have always demonstrated such levels of fidelity, or whether better birth control devices might allow for higher infidelity without increasing non-paternity rates. This is still very much an open question, Larmuseau tells OZY. “It could be that humans were more faithful previously, or perhaps they already knew about how to avoid unwanted pregnancy.”
Larmuseau and his colleagues hope to tease out some of the factors involved with extra-pair paternity rates, including the importance of social control and environment, in future research, and are currently examining the difference between rates in villages and cities. For now, though, the prospective cuckold can rest a bit easier knowing that, in all likelihood, the only act of deception he’s been nursing and rearing all these years is not his child but his overactive imagination.