Category Archives: Sexual Selection

Was Freud Right? Are You Sexually Attracted To Your Parents?

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No, you probably are not.

Well, that was easy. Given that sexual reproduction evolved specifically to introduce some genetic diversity to future generations in order to remain ahead of the more quickly evolving parasites (Ridley, 1993), the suggestion that humans would also have some adaptations that predisposed them to breed with their immediate relatives seems misguided. Freud – I’m told – had suggested that children really did want to have sex with their parents, and it was only through imposition of a cultural taboo against incest that such drives were thwarted. It’s just one of the many things he was wrong about.

“I don’t always talk about your mother, but when I do… wait, never mind; I do always talk about your mother”

Might there have been something to that notion of Freud’s though? No. Go read the introduction again if you’re still confused on that point. However, there is at least one recent research paper in which the authors suggest that there may in fact be some forces at work that generate sexual attraction to closely related family members that a societal taboo is needed to stand in the way of. In a series of three experiments, Fraley & Marks (2010) attempt to demonstrate that possibility.

In the first experiment, subjects were either primed with a picture of their opposite sex parent, or were controls that were unrelated to that parent. Subjects were then asked to rate a few pictures of opposite sex strangers for their sexual attractiveness. The results showed a slight tendency for those who saw a picture of their parent to rate others as more attractive (a difference of about 0.2 on a scale of 1 to 7). The second study went a bit deeper. This time, participants had their own face morphed from 0 to 40% with those of opposite sex strangers and rated the new photos for attractiveness; the control group rated the same pictures, but were not the person being morphed into the photos. The results showed a similar pattern: there was a slight tendency for people who’s faces had been morphed into the photos to rate them as more attractive (a difference of about a 0.4 on the same scale), relative to the controls. Finally, in the third experiment, the researchers lied to the participants about how much of their face had been morphed into the photos and mentioning the study was examining incestuous tendencies. This time, the effect reversed; participants rated the pictures with self-morphs as being slightly less attractive, relative to controls.

So where does that leave us?

Hiding in our closest, aka “The Shame Cave”?

Are we to admit Freud was onto something? No, and stop asking that silly question. Since I’m a big fan of theory, naturally my first question was: what was theory guiding this research? According to Fraley & Marks, the following findings need an explanation: (1) people tend to enter into relationships with others who are similar physically on a variety of traits, (2) that people tend to enter into relationships with those who live around them and are familiar, and (3) people find those who they are exposed to more frequently more attractive than those they’re exposed to less frequently. However, those three findings do not a theory make; they need a theory to explain them, preferably one that doesn’t cut again incest avoidance. Here’s a simple and probable one that accounts for at least part of the picture here: sexual selection.

Take any species; since I like peacocks, I’ll use them. When mating season roles around, the peacocks flaunt for the peahens, they have steamy bird sex, and soon after a new generation of birds are hatched into this world. The peacocks will inherit their father’s sexy tails, and the peahens will inherit something else: their mother’s preferences for those sexy tails. If those sexual preferences weren’t inherited, mating in the next generation would be random with respect to the tails. Since it isn’t, we can safely assume that, to at least some extent, the preferences are hereditary.

Just like the inter-generational preference for hunting equipment. I’m a shotgun man, myself.

So let’s return to the facts in need of an explanation. Picture your mother and father having sex to conceive you – make Freud proud. Whatever physical traits your parents had will be passed onto you. Additionally, whatever preferences your parents had for those traits that attracted them to each other will be passed on as well. That would seem to be able to explain (1) and the results of the photo manipulation study fairly well. By morphing in your own traits to the picture to some degree, you’re morphing in those same traits that you’re going to tend to have a preference towards. The result? You find those pictures slightly more attractive.

How about the first experiment that primed pictures of the parents? It seems at least plausible that if one truly found their opposite sex parent attractive, ratings of strangers would go down by comparison, not up. Concluding that one found strangers more sexually appealing because of that sexual aversion to their parents would be just as consistent with the data; at the very least, it can’t be ruled out by the results found here. As for the third experiment, admitting a sexual attraction to one’s own family can be quite socially damning, so it hardly seems surprising that people would avoid doing so.

“You look just like my sister and that is so hot! Would you mind wearing her clothes?”

Now I want to look at how the authors explain their results. Fraley & Marks (2010) suggest the following:

…the mechanisms that promote familiarity, bonding, and attraction are most likely to operate on inputs experienced in the early family environment. For example, if sexual imprinting really takes place in humans, then one’s early interactions with primary attachment figures can play an influential role in shaping the “ideal” for what kinds of people one will find attractive…

A tempting suggestion for some, no doubt, until one asks some perfectly relevant questions, like: why would the sexual imprinting take place during early interactions in childhood? Why would the stimulus that the imprinting responds to be the caregivers in the house (especially them, given the costs of inbreeding), as opposed to the environment outside the family? Combining the two questions gives us the following: Why would anyone suppose evolution had designed our psychology to become sexually attracted (in the long term) to the physical traits of our close genetic relatives at a time that we are pre-reproductive? Frankly, I can’t think of a reason we would expect that to happen, and one isn’t suggested in the paper.

On the same token, Fraley & Marks (2010) go on to suggest that the aversion to incest is simply a matter of habituation – as opposed to the Westermarck effect – but again offer no reason as to why habituation would have this particular effect. At the same time, habituation would also seem to make people more attractive the more familiar they were, according to the author’s interpretation of their work, and while Fraley & Marks (2010) note this contradiction, they don’t do a good job of explaining it away. They try to draw on some kind of distinction between the conscious and unconscious recognition of the familiar, but I don’t think they make a case for it.

On the whole, that is a very unsatisfying explanation, especially compared to other models of incest aversion. Point: Westermark. Freud is still wrong.

References: Fraley, R.C. & Marks, M.J. (2010). Westermarck, Freud, and the incest taboo: does familial resemblance activate sexual attraction? Personality and Social Psychology Bulletin, 36, 1202-1212

Ridley, M. (1993). The Red Queen: Sex and the Evolution of Human Nature. Harper: New York.

Discount Engagement Rings

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One day, a man is out shopping for an engagement ring in preparation to pop the question to his girlfriend. After a browse through a local jewelry store, he finds what he thinks is the perfect ring: It costs $3000, and even though he’s a man of modest means, he figures he can just afford it. As he prepares to make his purchase, another customer walks up to him and informs the man that the jewelry store down the block is having a going out a business sale and selling an identical ring for only $300.

What’s the boyfriend to do? Clearly, the ring on a 90% discount is the better deal, but something about buying a discount engagement ring just might not sit right with some people. While I don’t have any data on the matter, I could imagine that if the girlfriend in question found out that her (previously) stunning engagement ring was bought at a steep discount, she probably wouldn’t be pleased with her boyfriend’s financial responsibility, and that young bachelor who moved in down the hall might seem just a little more tall, dark, and handsome.

One of these rings will lead to a lifelong marriage and the other to not having a girlfriend; neither one leads to sex with that woman.

Pictured above is a $3000 diamond ring and a $300 cubic zirconia ring; try and tell the difference just by looking (good luck). The reason that a cubic zirconia ring, as opposed to traditional diamond one, would probably not sit well with many women is not because of any noticeable aesthetic quality of the ring itself.  There are, apparently, a number of ways to test and see whether you have a diamond or not, but that these tests exist (and can often be inconclusive to many) demonstrates that untrained people without special tools or knowledge have a hard time telling the two apart (which the comments confirm; many suggest the best way to tell them apart is always to ask an expert). In the specific case I gave initially, the two rings would, in fact, be identical in design and material, so the only difference would be the cost.

In the case of engagement rings, however, cost is the point. The high cost of an engagement ring functions as an honest signal; not honest in sense that they ensure fidelity or a lasting relationship, but honest in the sense that the signal is hard to fake. A poorer man could not afford a more expensive ring and his rent and his drinking problem. Dave Chapelle summed up this principle nicely when he said, “If a man could fuck a woman in a cardboard box, he wouldn’t buy a house”.

Not only does he still get laid all the damn time, but he didn’t have to give up drinking either.

This is precisely the reason people care about whether there’s a diamond or a cubic zirconia in jewelry; while both are sparkly, only one represents an honest signal, where the other is a fake signal that does not reliably distinguish between the ability to invest and inability to do so; one can signal a willingness to invest, whereas the other does not signal as well.

Examples of signaling abound in the biological world, and for good reason: when the sex that does the most investing in offspring – typically the female – is seeking out a mate, they need to assess the quality of the many potential mates. Since the investing one will be stuck with the consequences, good or bad, for a long time, it’s in their best interests to be more selective to get the best package of genes and/or investment. Males displaying costly ornaments – like peacocks – or behaviors – like bowerbirds – are able to demonstrate they can afford to shoulder the hard to fake costs involved in growing/maintaining them and still survive and flourish; they have been “tested” and they passed, guaranteeing their fitness to the choosy opposite sex (Zahavi, 1975).

We’ve all dealt with the inconvenience of pants that are too long at some point: you occasionally step on them, they shred as you walk along the street, they get dirty as they drag, water soaks up the back of them and feels awful on your legs, and that’s only for pants that a slightly too long. Imagine having a pair of jeans that happen to be a few feet too long, that you make yourself, you can never take off, and all your prospective partners will judge you by their quality. Also, lions are trying to eat you.

Seriously, this thing is practically begging to be killed.

Only those who are able to find the required materials, invest the time and skill in building, cleaning, and maintaining the pants would be able to keep them in viewable shape. Further, those pants would be serious inconvenience when it comes to doing just about anything, so only those who were particularly able would be able to maintain garments like them and still function. Lazy, unskilled, careless, and/or clumsy people would reflect those unfavorable qualities in the state of their pants. One could take off the pants to avoid all the wasteful insanity, but in doing so they’d be all but committing themselves to a lifetime of celibacy, as those still wearing the pants would attract the partners.

If you’re a good observer – and I know you are – you’ll probably have noticed that costly signaling can take many forms: from engagement rings, to bodily ornaments, to behavior. Costly signaling is relatively context independent: the important factor is merely that the behavior is hard to fake and expensive, in terms of time, money, energy, foregone opportunities, risk, etc. It can be used for a variety of goals, such as courting mates, impressing potential allies, or intimidating rivals. We all engage in it, to varying degrees, in different ways, for several purposes, likely without realizing most of it (Miller, 2009). It’s something fun to think about next time you slip into an expensive designer shirt or rail against the evils of branded products.

References: Miller, G. Spent: Sex, Evolution, and Consumer Behavior. New York, NY: Viking

Zahavi, A. (1975). Mate selection – a selection for a handicap. Journal of Theoretical Biology, 53, 205-214