Fellow Skepchick Mindy alerted me to this story in The Atlantic about some new evolutionary psychology research concerning promiscuity and morality. As usual, the reporting on the research uncritically reproduces all sorts of essentialist ideas about sex/gender and sexuality while reporting on the research. As usual, I am highly skeptical of any science reporting, much less science reporting on evo psych research.
So I went and pulled the research article itself to give it a look at see just how accurate the reporting was. And, unfortunately, it’s pretty freaking accurate.
The conclusions of this study rest on a couple of highly problematic unexamined assumptions.
One of the premises of the research is that “in order for a man’s parental investment to benefit his offspring, he must know who his offspring are and establishing paternity was probably a major adaptive problem for ancestral humans.” But this premise is based on the assumption that people in all societies share the same understanding of biological relatedness that Euroamerican societies do. However, we know this is not the case because when we look at the ethnographic record we see all sorts of variation in how people think about their relatedness to others. Most kinship systems, in fact, are not based on what we would consider “true” biological relations, with lateral lineage tracing from parent to child. Rather, there are systems that are more lateral, where “mother” or “father” refer to what we would call the biological mother/father and all of their siblings (i.e., the person we would call “maternal aunt” is identified as “mother” and the person we would identify as “paternal aunt” is also identified as “mother”). In a society with such a kinship system, it would be incorrect to make the assumption that “fathers” are particularly invested in “knowing” who the “real” biological father is, because that is not what their kinship system privileges. That is a claim that would have to be sussed out with detailed ethnographic study.
There also seems to be an underlying assumption about “the nuclear family” here, with no attention given to the fact that raising children is often a communal activity rather than something only a mother and father do. In this sense, paternal certainty is less important because a child is taken care of by most or all members of a group, and so group resources rather than individual resources contribute to the successful rearing of a child.
Another example of how this assumption about biological relatedness is problematic is the different ways that people think about how babies are made. For example, Beth Conklin’s work with the Wari’ in Brazil touches on their ideas of how bodies are formed in the womb. They believe that a fetus must be repeatedly exposed to semen in order to grow strong while in the womb. So, the more sex (that results in male ejaculation) a woman has while pregnant, the stronger their baby will be once it is born. Conception in the Wari’ worldview is not a one-time event, but rather an ongoing process during pregnancy. And, on top of that, they believe that any men who contribute semen to the development of the fetus are the biological fathers. Yes, that’s right: it is possible in the Wari’ worldview for a child to have multiple biological fathers. In such a society, “paternal certainty” would not have the same sorts of implications as it would in other societies, and yet the present research does not even allow for the possibility that people in “ancestral human” populations could have thought of conception in radically different ways than we do. It makes the assumption that all people are concerned with paternity certainty as if “paternity certainty” has a universal cross-cultural meaning.
Another perhaps more pedantic issue I take with the research are their confusion of biological and anthropological terminologies. In a section of the paper where they review some of the literature on mating strategies “across species and cultures,” they use the words “monogamy,” “polygyny,” and “polyandry.” Certainly in biological or zoological settings, those words may be used to refer to mating strategies. But in anthropology, those words refer to types of marriages, not necessarily to mating strategies. So, for example, people in a monogamous marriage (i.e., a marriage that consists of two spouses married to each other) may not, in fact, be monogamous when it comes to mating. They may be “mating” with multiple partners. The authors muddy the water between mating strategies among non-human primates and other animals and human marriage practices, which are invariably cultural and, historically, were more about political economic relationships and alliances between families than furthering specific biological lineages.
A final problematic assumption in the research is that any “moralizing” about promiscuity is indicative of an adaptive mating strategy on the part of women (thus the name they give to their idea: the female economic dependence theory of promiscuity aversion”) rather than as the expression of a particular ethos that may or may not be adaptive. Furthermore, the assumption that “promiscuity” is a pan-cultural concept could be problematic. Any societies in which “promiscuity” is not conceptualized, if such a society has or does exist, won’t have any moralizing about it to study. How would that affect these findings? Indeed, how would one even go about asking these questions in such a society?
As with many other evo psych studies, there are some problems with the sample. The sample was made up of only Americans. The samples consisted of about 52% men in both studies and were overwhelmingly white (81% in Study 1, 78% in Study 2). Participants were recruited through Amazon.com’s crowdsourcing website (and they claim that this is just as good as the standard university student sampling, which isn’t really that great of a thing to be bragging about). The authors provided no other demographic information for the first study sample, but provided sexual orientation (90% heterosexual, 6% bisexual, and 3% homosexual) and geographic (people from all 50 states + DC) demographic information for the second study sample.
Still, as far as I can tell, the statistical findings aren’t all that controversial or troublesome, though I would have liked to see more caveats about this study only really telling us something about Americans. The studies found that “female economic dependence was a significant predictor of opposition to promiscuity,” and that “on average, women were more opposed to promiscuity than were men.”
But where I take issue with this study is in the discussion of the conclusions, and this is something that happens way too often in evo psych work. The researchers jump from those mostly unremarkable conclusions about Americans to this much broader interpretation (emphasis added):
Both studies provided support for the female economic dependence theory of anti-promiscuity morality. According to this theory, in environments in which female economic dependence on a male mate is higher, both a woman and her mate have a greater interest in maximizing paternity certainty. Because promiscuity undermines paternity certainty, both men and women should be more opposed to promiscuity by both sexes in environments where there is greater female economic dependence on a male mate.
These conclusions rest on unproved assertions that (a) all parents are invested in paternity certainty and (b) promiscuity impairs paternity certainty. But, as I discussed above, the idea that people (across human history and geographic space) are invested in biological paternity in the same ways that Americans are is not supported in the ethnographic record, and it’s certainly not evidenced in this research.
After stating these conclusions about how moralizing about promiscuity is an adaptive mechanism, the authors drop this little nugget of hedging language (emphasis added):
These results suggest that moral views about promiscuity are influenced not just by one’s own calculations about the value of a promiscuous strategy to one’s self, but also, and more importantly, by the norms that prevail in one’s community about the value of promiscuity.
In other words, the authors admit that cultural norms are more influential in moralizing about promiscuity than a person’s own valuing of promiscuity. This is kind of a “no shit” statement from the perspective of a sociocultural anthropologist, and highlights another flaw of this research, which is the overt focus on individual mating strategies at the expense of attention to sociocultural beliefs that may or may not be adaptive.
Right after allowing for the powerful influence of culture on views of promiscuity, the authors return to a typical evo psych stance:
This strategy of conforming to group cultural norms, however, should not be regarded as a ‘‘less biological’’ or ‘‘less individually-selected’’ behavior than that of selecting a personally-advantageous mating strategy. This is true for two reasons. First, adaptations for conforming to norms may have functioned to shield ancestral individuals from the negative fitness consequences of social ostracization. Second, anti-promiscuity norms are themselves proposed to be the outcome of individual-level fitness concerns related to paternal investment and paternity certainty.
So there you have it. A wonderful evo psych “just-so story” about how, even though views of promiscuity are certainly a product of sociocultural processes, no matter how influential sociocultural views of promiscuity might be, it still always comes back to individual environmental adaptation. Even when there is really no evidence to support such a claim.
If there is one positive thing I can say about this study, it’s that the authors do declare the need for cross-cultural attempts to replicate this research to see if their ideas hold up across different societies. At the very least, I am thankful that they recognize and admit how limited this research is in their concluding paragraph, especially considering how WEIRD Americans are. But, that sure didn’t stop them from making all sorts of claims about our evolutionary past on their way there.