by Greg Mayer
A lot of work in behavioral and evolutionary biology concerns the evolution of mating systems—polyandry, polygyny, monogamy, promiscuity, and the like—and elucidating the factors that lead to the evolution of one or another. Mating systems can be variable within a species, and human societies exhibit a range of mating systems, with monogamy and polygyny being perhaps the most common. But these culturally defined mating systems may exist more as aspirational norms than as universal practices. From a biological point of view, it is actual paternity and maternity that count, not what the culture deems most appropriate.
In a piece in the New York Times, Carl Zimmer takes a look at this in human societies, asking how often is it the case that the father of a family’s children is not the mother’s spouse, but rather some other male who has fathered the children through adultery. This is a popular theme of “reality” TV, but Carl concludes it’s an old wives’ tale, citing a review by Maarten Larmuseau and colleagues in press in Trends in Ecology and Evolution. Using a variety of approaches that have become possible only since the development of DNA sequencing, including ordinary paternity testing and the clever use of Y chromosomes in concert with family genealogies and historical migration events, they show that “extra pair paternity” (EPP, i.e. cuckoldry) is actually rather rare—only 1-2%.
Carl notes that this is not as unexpected as the myth would have you believe. In species with females who frequently have multiple mates, males evolve a number of adaptations to insure the precedence of their sperm over other males—and men have none of these sorts of adaptations.
But, as luck would have it, on the very day Carl’s article appeared, a case of human EPP is also in the headlines: of all people, it turns out that the Archbishop of Canterbury’s father was not his mother’s husband! As the Independent put it “DNA test reveals Archbishop of Canterbury Justin Welby is illegitimate son of Sir Winston Churchill’s private secretary“.
My doctoral mentor, E.E. Williams, always said that observations refuting your favorite hypothesis don’t come early in your hypothesizing; a Malevolent Nature ensures that they come only after you’re really convinced you’re right. And in the journalism version of this, the contrary example doesn’t come till you get your piece on the front page of the New York Times. In fairness to Carl, though, one example does not refute his general conclusion, and it isn’t even quite cuckoldry: the Archbishop’s mother had sex with the private secretary just before her marriage, so the birth of the Archbishop-to-be nine months after the wedding had been wrongly assumed to be the fruits of the wedding night.
Larmuseau, M.H.D., K. Matthijs, and T. Wenseleers. 2015. Cuckolded fathers rare in human populations. Trends in Ecology and Evolution in press. pdf
Great story!
I assume that 1-2% stat indicates how many fathers are *unwittingly* raising children that aren’t theirs.
Otherwise that number simply has to be waaaay off.
I’m suspicious of it myself, but maybe that’s because my two younger brothers both became the legal fathers of children their wives conceived with other men they were having affairs with. In both cases my brothers found out before the children were born and each time the biological father wanted nothing to do with the kids. One brother remained with his wife for a few more years before she left him (and not for the 1st guy she had an affair with but with yet another guy) while my other brother initiated divorce proceedings as soon as he found out. The outcome of his divorce was he did not have to pay alimony but he agreed to become the legal father and pay child support for the child. And in both cases the children are now adults and know about the affairs their mothers had. In my case, at 53 I’ve never married and never fathered any children nor have I ever had any desire to become a father.
Fascinating story. Good luck to all of you. I have my own story I could tell, but I’ll save it for another time.
What upstanding brothers!
The statistic I learned in first year anthropology was that 25% of the men that children call “father” are not their biological father. I don’t recall any proof being given, but on the other hand 1-2% seems kind of low.
One of my General Biology I instructors in CEGEP (the last biology course proper I did) said that he does simply blood typing in all general biology I classes and in all his (elective for other students) biology of sex classes. He said that some proportion of students, around 10-15%, learn that their parents aren’t who they thought they were. I don’t know how well his records were kept or whether students might have been making up answers for the parents (who are of course not tested in class, just the student).
“… “extra pair paternity” (EPP, i.e. cuckoldry) is actually rather rare—only 1-2%.”
I can’t find it now but I’m pretty sure I once read an article that said the percentage in the UK was much higher.
I was trying to remember the technical term “extra pair paternity” when I heard about the Wel … Wellsb … Archbishop’s case. Only point of it worthy of remembering in what is otherwise a non-event. It’s probably not even the only “Daddy Who?” moment this week in the CofE.
As “beef” says, this statistic probably refers to fathers un-knowingly raising other males children. Othwise, it’s considerably off even if I restrict my accountancy to my immediate family.
sub
Decades ago I read ( it might have been J Diamond) that blood type testing of babies in a hospital in London in the 1950s showed a much higher percentage of cuckholded fathers…I think it might have been as high as 15-20% but I don’t remember.
I read of a U.S. study years ago that estimated the instance of “bastardom” to be as high as one out of every nine births.
I heard this deal late last week:
it is just a hoot !
So is the Sun’s, “The Archbishop of Canterbury … … is, forgive me, literally a bastard.” !
I myself ‘d love a (paid, o’course !) gig as … … such a caption – writer !
Blue
I think there might exist particular moderators or local situations, that could kew the percentages.
For example, I remember, growing up, that one favorite past time of the old geezers in the small town close to where I lived, was to sit and watch the people in the square at weekends, to try to tease out all the local Baron’s illegitimate offspring, (the current and his forebears).
As it happened, I think they had a bit of help from the fact that the (Baron’s) male line suffered from dramatic early loss of hair, and a very memorable nose… 😀
One particular moderator would be during war. When many men are not at home the opportunities would seem to be greatly enhanced. Also, where occupations make living closely not an option.
Legally, in English law, I’m pretty sure the A of C is not a bastard. He’s the legal son of his mother’s husband since they were married when he was born.
That aside, very cool and interesting story.
I remember an article in the pediatric literature about childhood cancer that can be treated with bone marrow transplants. Testing of the parents for potential donation revealed a different father in greater amounts than 1% (in the US anyway)–something like 5% as I recall. I have been looking for the article but can’t find it right now–I’ll keep looking. This obviously presents an ethical conundrum for the pediatric oncologist. I think “You’re not a match” was the way to go most of the time.
That is a very nice hat.
Do you think he’s competing for the casting couch for the next Indiana Jones movie? “Indiana Jones and the Extra Pair Paternity” … has a sort of ring to it. “Ash nazg etc …”
Ahhh, the Black Speech. The whole RCC thing makes perfect sense now.
Agreed. Hats are the aspect of faith that is particularly attractive.
GCM
What we atheists need is our own Silly Hat
I wish my clothes would magically make me right about everything.
That one last fling. Good story.
Well, you know the old saying, “It’s a wise
archbishop…”
Even with a low percentage, EPP can have a high probability of confounding one’s family tree. Supposing only 1% EPP, how many generations do you have to go back before there’s a 50% chance of encountering at least one departure from the official tree in your ancestry? The probability would be 1-(.99^n), where n is the number of male ancestors. Given no inbreeding, you get to 50% in a little bit over 6 generations. (6 generations = 63 male ancestors, and you need 68 to reach 50% probability.)
Apology for the long comment.
One of the most intriguing research topics (for me (?)) is into human sexual selection. Darwin considered it first I think in 1871. I would like to recommend one further source for the discussion, Robert Martin’s book. 2013: How we do it, published by Basic Books (see Amazon). On pages 61-61 Bob also cites the figure of 1-2% (citing Alan Dixson’s book Sexual selection and the origin of human mating systems)for extra-pair paternity. (Note: Robert Martin, a leading expert in primate evolution, started his research under Konrad Lorenz.)For several years, when I taught an introductory course at the University of Chicago on Evolutionary Biology, he was a guest speaker on human evolution, and the students just loved his lecture, his wit, his special focus on the evolution on human’s large brain.. sorry, I digress I miss him, he left Chicago.
Getting back to topic (I am sure I violated a ton of Da Roolz just now): 1. Sexual selection has been and is going on in human populations. 2. Various human populations may (I think they do) feature different forms of sexual selection (meaning females of different populations prefer different types of human males, e.g., some females prefer tall males, e.g. the Netherlands?..). 3. I hypothesize that this fact causes at least some for the (unnecessary) animosity between various human groups. If we recognize that, then maybe we can find reconciliation without resorting to violence.
What do I know? I look at dwarf males in spiders and long-legged males in millipedes as examples of sexual selection.
It has always astounded me that fundamental aspects of evolutionary biology are completely absent from online discussions on human sexual behavior by conservative outlets and authors (maybe I am not searching hard enough), e.g.First Things, Robert P. George, Ryan T. Anderson.
My take: (Largely +-) Monogamous mating systems are neither the invention of any religion (Christian or otherwise) nor the result of divine intervention, they result from evolutionary processes. Monogamy appears to be (at least partly) supported by Oxytocin (we may not have the need for ‘another hypothesis’). But, as Bob Martin explains in his book, humans may not be as strictly determined as gibbons or gorillas in their mating systems. Humans may be more flexible and react to different ecological situations (including resource restrictions) by employing various mating systems (the current hominid phylogenetic hypotheses do not contra-indicate the flexibility hypothesis).
I’ll stop, I violated enough Roolz. But I would be very interested in a serious, on going discussion of sexual evolution in human populations.
Interesting contribution, Petra–thanks!
In the development of the Western ‘traditional marriage’* there were a lot of blind eyes turned. Birth certificates automatically were issued with the husband listed as father, doctors or registrars rarely questioned this. That system actually worked, left fewer cast off children that might become wards of the state or worse.
In many areas, plenty of people had a sense of what was going on, they just avoided looking to closely.
*figured using that terminology would get some attention here.
Is it not usual in the mammalian animal kingdom for female ovulation to a full blown front page advertisement i.e. colours, scent pheromones, hanging out at leks but not so with female homo sapiens.
Concealed ovulation from what I gather can mean two things. One, it keeps males guessing and is a way of holding a male true to help in rearing the young and two, the female gets to choose who is the father and EPP is an option. One male for reliability and one for hotness, whatever is deemed those qualities by the female.
In this case above the secretary was not.. or was he?
Mores the pity, we end up with a Archbishop with perhaps a little over influence from alcohol, at a guess. And still more, is the said Archbishop compensating for being conceived out of wedlock, nothing personal mind you for it matters little, just wondering.
“DNA test reveals Archbishop of Canterbury Justin Welby is illegitimate son of Sir Winston Churchill’s private secretary“.
Namedropper!
Social climber!
(Well, if you’re going to have an unauthorised father, that’s a way more prestigious choice than the milkman).
cr
Prestige is right. It’s clear that one of the significant driving forces of human society is status. If you are given a choice between a milkman and someone close to the most powerful guy in the nation, doesn’t the romance follow the power? Where’s the status gene anyway?
You think you joke–but the subject matter resembles nothing so much as the traditional “alpha male” concept in non-human societies. I suspect there are quite a few, rather ancient, genes at work, here. 😉
Right. I’m sure at least one gene is there for the selection of a larger SUV than your neighbor.
Chuckling out loud! 😀
Even within one nuclear family, where the children are the biological offspring of the same mother & father, there can be great variation in sexual behavior. One of my brothers (I’m the eldest of 3) was very sexually active from the time he was 13 but I was so intensely shy I was 19 before I lost my virginity and even in the 3.5 decades since then I’ve mostly been involuntarily celibate for reasons that have nothing to do with physiology. Yeah, has the makings for a bad comedy.
I’m surprised that no-one has yet mentioned the most famous case of EPP in history, which supposedly happened just over 2000 years ago… 🙂
I remember a wonderful seminar by a medical geneticist in Sheffield ca 1964. A genetic disorder in an aristocratic Derbyshire family suddently disappeared in the next generation. He suspected that cuckoldry was more common in the upper classes than in the working classes during the 19th and early 20th Centuries.
Malcolm Peaker
Just catching up – I saw that story. Thanks Greg for the extra info – very interesting…