"This study throws open the door to understanding why this phenomenon is so widespread," Reid says. "It's still an enigma."
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A 17-year-long study upends the most common evolutionary explanation of female infidelity
"This study throws open the door to understanding why this phenomenon is so widespread," Reid says. "It's still an enigma."
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38 Comments
Add CommentThe female in an EPC (Extra Pair Coupling) ran into one of the promiscuous males.
Reply | Report Abuse | Link to thisGosh maybe their just horny. Or we could demonize men some more =:)
Reply | Report Abuse | Link to thisOr maybe it's a way of hedging their bets, in case the regular male partner dies off.
Reply | Report Abuse | Link to thisWhy don't they check the success of the illegitimate offspring of the males as well? I suspect they also have less mating success, and their offspring have less success.
Reply | Report Abuse | Link to thisThis certainly seems to be true with human children of fathers who have children both inside and outside of marriage. I have often thought about writing a book about it about historical figures. One could examine the likely prospects for the Schwarzenneger and Edwards illegitimate children. And how about the effect on the children of the primary coupling as well?
And human beings are a lot more complex and take a lot longer and a lot more resources to raise than birds. So it seems the effect of actually not being evolutionarily successful would be more exaggerated.
I think emotions have more to do with infidelity in humans. If a woman feels paid attention to and cherished and trusts that her mate is faithful she is more likely to be faithful (in my opinion.) I think that scientists who fail to take emotions into consideration when performing these studies are making a big mistake. Of course, economics also play into emotions...if a woman feels well cared for financially (and thus more secure) she is probably also less likely to stray (assuming being "taken care of" financially is part of what she wants in a mate.)
Reply | Report Abuse | Link to thisMost studies of human infidelity also show a frequency somewhere in the 20% range. Interesting that a similar rate is seen in other pair bonded species. The rate is high enough and consistent enough to suggest that there must be more to the phenomenon than a genetic left over.
Reply | Report Abuse | Link to thisI guess it has been shown that men in the higher income and power positions tend having more lovers than others, some kind of women rewarding success in a way similar to the herds of deers where the dominating male impregnates many females, but an explanation is yet to be found in facts as the rapid spread in pre-historic times of advantageous genetic traits such as persistence in adulthood of the enzymes that allow bays to use the milk's sugars in groups that relyed on cows, sheeps and goats sine milennia other than a tendency in women to make their man horny. However, a recent UK study in unselected newborns showed a rate of genetical non-matching between the baby and their supposed male parent never higher than 2 or 3%. The subject is interesting, and knowing the old roman assertion "father always uncertain", and the comments by Jesse Bering that point that a women can become pregnant from a man she never met, by one of his partners bringing her sperm from a third man the woman having had previous sex with her last men passing sperm from opens an ocean of uncertainties.
Reply | Report Abuse | Link to thisWould there be an advantage for isolated populations to get some genetic diversity when the chance arrives.
Reply | Report Abuse | Link to thisAnd studies in the UK or other Western societies bear the burden of Western mores. Other places, other ways. In some pre-technological societies where it thought that a woman assembles her child from parts of various men, that's what she attempts to do. The tribal comedian gives her baby a sense of humor, the best hunter, valor, the shaman, connections to the spirit world, etc. Whether or not we share that belief, it has worked for them for centuries.
Reply | Report Abuse | Link to thisI have a vision of a botanist studying a sapling in a forest and saying to his apprentice, "I wonder if any trees are nearby?"
Reply | Report Abuse | Link to thisVestigial male behavior is to be expected in females simply because very little genetic difference exists. Thus a strong inherited instinct in men must also have expression, but perhaps only slightly less so, in women. It need not have ANY evolutionary advantage and could even be moderately disadvantagous.
Going the other way; same thing -- evolutionary traits strongly bound to women are very likely to manifest in men even where no evolutionary advantage exists, such as the traits sometimes associated with homosexuality.
This happens because men and women happen to be the same species. I suspect that may come as a surprise to some, a hypothesis that needs further testing ;-)
Duh. RTFA.
Reply | Report Abuse | Link to this"Reid is also investigating whether female promiscuity is a genetic by-product of the male version. If there are genes that encourage a male to be promiscuous, he might pass those genes on to his daughters, even though they may not benefit from the behavior."
Exactly so.
Yeah, blame it on the guys. Classic!
Reply | Report Abuse | Link to thisThe most important statement made in this article is: "...because the results need to be confirmed in other populations and other species."
Reply | Report Abuse | Link to thisWhy are (at least the reports of) behavioral studies of a very narrow sample population so commonly characterized as having universal implications?
I think they measured the wrong thing. Infidelity would be an advantage if it resulted in more total grandchildren than faithful partnerships, regardless of whether the parent was from a pair coupling or an extra-pair coupling. They should compare pairs in which some offspring result from extra pair coupling with pairs in which no offspring from extra pair coupling occur.
Reply | Report Abuse | Link to thisThe hypothesis could then be that a genetically based high libido was the real advantage and the infidelity simply a by product of that characteristic.
can't there be a simpler explanation. What if after committing the female realizes that the male partner is incapable and finds someone else who can take better care of the offsprings so that have better chances of survival.
Reply | Report Abuse | Link to thisPerhaps to explain a little more clearly, if the reproductive behavior of birds applies to other species, including humans, then why do different species have differing reproductive behavior strategies?
Reply | Report Abuse | Link to thisIf I recall, there are species of rodents who are strictly monogamous while their very close cousins strictly play the field. General characterizations of specific species' characteristics cannot be reliably extrapolated to other species.
Fair enough jt but when the same behaviour occurs in a number of species it is reasonable to consider that similar factors may be in play. It is a bit irritating when a study of birds immediately becomes a discussion of human sexuality but it is quite possible that the factors driving a bird species towards infidelity are related to the factors driving a species of primate in the same direction.
Reply | Report Abuse | Link to thisIs there some basis for presuming that bird behavioral factors apply to humans?
Reply | Report Abuse | Link to thisblindboy said "The hypothesis could then be that a genetically based high libido was the real advantage and the infidelity simply a by product of that characteristic."
Reply | Report Abuse | Link to thisSounds reasonable to me.
Here's an excerpt from 'What is the Primary Fundamental Right?'
"Undressed fertile looking women in men's glossy magazines in the early sixties and seventies combined with low taxes probably had a lot to do with the success of the American economy prior to the wholesale adoption of big government in the nineties. Male sexual desire apparently promotes entrepreneurism which is the back bone of Capitalism."
http://www.primaryfundamentalright.org/index.php?pageName=pfrWhatIs
Always struck me as interesting that the words 'Slut' and 'Lust' use the same letters.
Nipples!
Reply | Report Abuse | Link to thisThis makes just as much sense as the original article's conclusions. It's totally nonsense to put human morality into sexual behavior of animals, including humans.
Reply | Report Abuse | Link to thisYears ago I read that female promiscuity in mammals could be measured by (indirectly, by observing) male testicle size. That highly promiscuous females cause males of the species to evolve / adapt to produce higher sperm counts, so that their DNA triumphs in a statistical battle for fertilization in the face of increased competition. By this benchmark, it was surmised (at the time) that human females must exhibit relatively high promiscuity - relative to other mammals - based on human male testicle size / overall body size ratio.
Reply | Report Abuse | Link to thisAmongst primates and possibly other mammals, the greater the size difference between males and females, the less monogamous the species. Humans would seem to fiti neatly into this continuum being slightly sexually dimorphic and less than perfectly monogamous.
Reply | Report Abuse | Link to thisThis study itself might be fine, but to draw any kind of conclusion from it about humans, or even mammals, is pure rubbish. And rubbish that I've seen repeatedly coming out of the "evolutionary psychology" discipline. Its practitioners seem to be on a mission to support tired old notions of western gender roles and the importance of the nuclear family. If these guys had taken even one class in cultural anthropology they would know that the nuclear family is a fantasy even in humans. And to infer something from birds? Please.
Reply | Report Abuse | Link to thisNot surprising at all. Stephen Jay Gould wrote about this in, among other essays, "Male Nipples and Clitoral Ripples." His point is that there are some things you get solely from being a human being, whether you need them or not. While I would argue with the implication that the human clitoris is as useless as male nipples, still his point is a good one.
Reply | Report Abuse | Link to thisGood one. And cows? Ha ha bulls have gigantic testicles. Most herd animal females are highly promiscuous -- I still recall our pony mare "smiling" at every male that went by -- which probably accounts for all the fighting among males. So yes it all kind of "hangs" together. Still making wild inferences like these is hardly scientific.
Reply | Report Abuse | Link to thisHard to see any particular correlation there. Among primates the size difference is greatest in gorillas and they are more monogamous than their cousins the partying bonobo with nearly identical sizes. Also herd animals mostly have near-identical sizes and they are highly promiscuous. Oh well.
Reply | Report Abuse | Link to thisJT;
Reply | Report Abuse | Link to thisAs is common practice in the Scientific Community when referring to "Human Sexuality" we shall use the code words;
"Birds and Bees." The former generally relating to the female of the species, the latter the male. Unless random use is used for further obfuscation purposes.
Are you sure you're old enough to be reading these
"Scientific" topics?
Gosh, that wouldn't make any difference if they already had a mate.
Reply | Report Abuse | Link to thisI think there are some assumptions made in the article that may lead to unwarranted conclusions.
Reply | Report Abuse | Link to thisFirst, the author seems to assume that the population is at equilibrium genetically. I'd like to know about the genetics of promiscuity in these birds. After all, evolution requires not merely variation and selection (both of which seem to be present) but the variation also has to be heritable. I'd like to know what proportion of the offspring of the promiscuous females are also promiscuous, and likewise what proportion of the offspring of the non-promiscuous ones. Given the extreme selection pressure against promiscuous behavior, it seems unlikely that the population is at a equilibrium genetically. Selection may have "used up" all the existing genetic variation, and further evolution would depend on new mutations (or immigrants with variants) that prevent promiscuity.
Second, it is possible that migration is bringing genetic variants permitting promiscuity into the population from elsewhere where it is not at such a large disadvantage.
Only with extreme caution can we establish a link between animal behavior and human behavior. Yet not all humans are equally human: a few renounce the amazing opportunity only we have, to override instinct by rational analysis. For those, their lifestyle make them more akin to animals as they are ruled by instincts mostly. For others their choices makes them more akin to the sentient and analytical beings of our future.
Reply | Report Abuse | Link to thisAnyway can someone tell me what is the purpose of such study?
What are the applications of the possible findings?
The purpose of this study, like most scientific studies, is to see if our hypothesis is right. As the article says, for a long time scientists have thought they understood why females are promiscuous, because the offspring may be more diverse. This study shows that the hypothesis is wrong, at least for these birds for the duration of the study.
Reply | Report Abuse | Link to thisWe can apply this study to humans very easily, by saying, "No, we don't really know why women are promiscuous."
Another factor not covered by this study is the fact that it is limited in time. Perhaps females really do benefit from having diverse offspring, but only once in a great while, such as when a disease hits the population. When that happens, diversity may be so critical to survival that it instantly (in a year or two) boosts the genes that permit promiscuity, or reduces the genes that cause fidelity.
Reply | Report Abuse | Link to thisI'd also like to know if the study has enough data to be able to say whether it is really true that males boost their reproduction using promiscuity. I can think of reasons why it might not, such as if the effort to mate with females who are not their mates detracts from the effort to feed the offspring of their mate. Or perhaps the mate of those strange females somehow recognizes that those offspring are not his, and does not feed them, and therefore they are not fed enough to thrive.
I think it's time to go look at the original article.
I thought the best evolutionary strategy for females was to be relatively promiscous, but if possible, avoid letting any partner know that there were others. This enables them to accept gifts and protection from more than one mate. This also offers insurance in the event that a mate moves on or is killed.
Reply | Report Abuse | Link to thisThis is probably linked to dominance-induced behaviors,( which can take many forms in humans: fashion, big cars, stage, anything to get everybody's attention ) and concerns both sexes and is inherent to any social arrangement where several members of the same species interact. The passive or active mode of dominance is always beneficial for those involved, since equals are condemned to fight each other.
Reply | Report Abuse | Link to this"...having higher quality offspring..." Uh, how is this known simply by cheating on a partner. Stuff happens as in the entropy department. Ergo, does quantity imply quality. Methinks not. Anyone else?
Reply | Report Abuse | Link to thisNOTE: We, as a species, shouldn't forget that natural trait called the "Motivational Triad" which is within us all, from the microbe to the mammal; There are 3 stages of this phenomenon... 1st: Pleasure or Seeking such, 2nd: Avoiding pain, and 3rd: To use or exert the least amount of energy. This piece of data should fit quite nicely with this nonplussed noun of nature, which I would call... evolutionary infidelity.-Dane Dino Butler
Reply | Report Abuse | Link to this"...a better way to understand why female promiscuity evolved...is to determine whether those illegitimate offspring actually have more babies."
Reply | Report Abuse | Link to thisThe study is completely flawed based on that one circular premise. Evolution is a balancing act of quantity versus quality, among other things. Bigger does not necessarily mean better, and smaller does not necessarily mean worse. Likewise, less or more offspring is not a meaningful metric unless you can explain, in specific context, why one might be preferable to another. Merely saying "more offspring" represents a "reproductive advantage" is meaningless, because "advantage" is ill-defined, or worse yet, defined a question-begging circular premise.
Sea turtle infant mortality is responded to by gajillions of sea turtles that all hatch at once - with millions fo offerings to the destructive gods. So there's your argument for sea turtle polyandry, but even if it is correct, it does not necessarily explain polyandry of other animals.