Death… It's A Living

For the most part, people agree who is and is not attractive. Regardless of race, gender, culture, and sexuality, a beautiful face is considered a beautiful face. As I have previously written, the only necessary and sufficient explanation of facial attractiveness is prototypicality or averageness. Faces that do not veer far from their categorical average are considered as more attractive than a face of average attractiveness. In this way, faces are the same as every other natural category: We prefer average dogs and average birds and average fish. It’s even true for many artificial categories. Several lab studies have shown preferences for averages of stimuli created on a computer with which the participants have no prior experience.

All that being the case, we still don’t have a fully satisfactory answer when it comes to what makes someone or something the most beautiful. Although prototypicality provides a baseline signal of safety/familiarity/approach and it is considered as attractive, it does not necessarily send the signal, “Wow, you need to know who this person is right now”. What physical traits must be added to an otherwise prototypical face to engender this response?

My answer begins with the demographics that I disregarded in the first paragraph. Although everyone responds positively to prototypicality, only certain people are more likely to respond positively to certain traits. In other words, while beauty in general is not in the eye of the beholder, the traits that enhance an otherwise prototypical face are.

Recall from previous posts that I am considering beauty not as something “real” but as a real signal of something that is useful to our genetic survival. The most obvious first candidate to play the role of “something” is a mating cue. In fact, a large majority of the academic literature on attractiveness preferences has assumed that attractiveness is the motivating factor that causes organisms to approach conspecifics who are potential mating partners. Theoretically, the more beautiful we find someone, the better of a fit (we think) they might provide for our genetic survival.

In other words, to best understand what makes people the most beautiful, we must understand individual differences. Before getting into the nitty-gritty of why one individual might prefer one set of physical traits more than another individual, it might be helpful to start with the predictable changes in preference that occur across individuals. And the most predictable differences in preference occur across the sexes.

Finding Sex Depends on Sex

Again, a brief but important aside is needed. Note that I used the word “sex” and not “gender”. Although outside of psychology these words are often used interchangeable, they are very different. Sex is the biological distinction between what we typically consider male and female; that is, it is the phenotypic expression of having either the XY (male) or XX (female) chromosome pair. Because there are additional/alternative combinations (e.g., XXY and so on), even sex is not truly binary. However, because non-binary sexes are thought to occur (at most) in 0.2% of all births, it is convenient if not entirely accurate to think about sex as mostly binary. One’s gender, on the other hand, is the social role one takes in relationship to one’s biological sex. For example, most us who carry the XX pair will look and behave in ways that are socially consistent with a feminine gender (and most us who carry the XY pair will look and behave in ways that are socially consistent with a masculine gender), but far from all of us. In fact, there many, many ways in which an individual could behave that are simultaneously consistent and inconsistent with their biological sex. As such, the number of genders is nearly limitless (although, very broadly, most people could be classified as masculine, feminine, androgynous, or transgender). A full breakdown of every gender would likely be impossible and leave at least some people out. For my purpose, it is also unnecessary because the behaviors I will be discussing are true of both human and non-human animals. By definition, all animals have a sex but only humans have a gender.

With that explanation out of the way, differences in sex provide some of the most predictable attractiveness preferences. But it’s not that (heterosexual) men prefer female faces and (heterosexual) women prefer male faces. Although that is part of the story, it is far from the most interesting. Recall that attractiveness is the perception of a biological cue that should motivate some behavior. If that behavior was as simple as “approach that stranger and have intercourse!”, then there probably wouldn’t be differences between the sexes in terms of attractiveness preferences; perhaps prototypicality would be enough of a turn-on. Thus, the key to understanding the differences between the attractiveness preferences of men and women is to first understand that the sexes have very different motivations when it comes to attractiveness, and that can only be based on the most fundamental biological distinction between these groups:

Females can become pregnant; males cannot.

Although that distinction between the sexes might be obvious, it cannot be underemphasized with regard to its role in shaping the behavior of our species. In fact, it would not be outlandish to argue an extreme position: The fact that females can become pregnant (and males cannot) is the origin of all human sexual behavior and all sexual differences. This position, though extreme, is nevertheless in line with a fundamental idea in evolutionary science called Parental Investment Theory. From my point of view, it is impossible to fully understand the differences in what women and men find attractive without understanding the basic tenants of parental investment; therefore, an explanation is in order.

Parental Investment: A Primer

The goal of all life is to continue to live in some form. As I’ve written elsewhere on this site, the specific goal of life is genetic survival (which is why almost all actions of sensation and perception are devoted to detecting signals that direct our actions to and away from various stimuli). It’s easy to think that genetic survival begins and ends with mating. In some species it does. For example, oysters mate by spewing either millions of eggs or billions of sperm into an estuary. The male and female will never meet, and their offspring will never know their parents. Oysters become sexually mature when they reach a certain size (usually between 2 months but before 1 year old). Combining the shocking number of gametes ejected into the water with the short turnaround between birth and the ability to conceive, oyster parents can be relatively sure that at least some of their offspring will have their own offspring.

Buried in that description of tawdry oyster sex lies the actual key to genetic survival: grandparenthood.

To ensure success in life (at least success as a lifeform), an organism must not only mate and pass on its genes to the next generation, but also it must protect the life of that offspring long enough for it to reach sexual maturity and pass on its genes. Thus, it can reasonably be argued that grandparenthood is the point of life. Perhaps it should be no surprise that, compared with new parents, new grandparents are some of the happiest people on Earth. They are the ones who have finally made it.

In the evolutionary sciences, we call that second stage “investment”. Parents must invest resources—whether that be biological energy, social energy, or actual finances—to give their children the best opportunity to have their own children. Oysters have decided to play the odds. Although it seems like they have invested nothing compared with a middle-class family wondering how it will afford $200,000 for a 4-year college degree, that’s not correct. They’ve invested evolutionary points in becoming a species who can release millions and billions of gametes at one time. Oysters may be a species full of deadbeat moms and dads, but they will reach grandparenthood all the same.

The evolution of mammals took a different path. No mammal can release millions of eggs; even the most Fertile Myrtil of the mammals, the tailless tenrec (Madagascar’s answer to the shrew), can “only” have up to 32 offspring in one litter. Instead of investing in egg creation (and release), mammals spent their evolutionary points on internal gestation and a motherhood characterized by milk giving. In most cases of mammalian motherhood, the parent rears her cubs or pups or calves through their most fragile developmental periods. She seeks to ensure that they reach a point in development where they can reasonably be expected to find their own food, to find their own mate, and produce grandcubs or grandpups or grandcalves, thereby enabling genetic success.

Human motherhood is almost as extreme as oyster motherhood, but in the opposite direction. Human females only release one egg every 28 days (this may even be the case among fraternal twins—there is no evidence that humans are capable of releasing more than one egg at a time… but this is a story for another time). Should that egg become fertilized, the zygote (then embryo, then fetus) must gestate for 40 weeks. This an incredibly long gestation for a species that, for most of its history, was nomadic. A cavemother-to-be who conceived in late spring would have been pregnant across all four seasons. To make matters even more difficult, even full-term neonates are born altricial compared with their mammalian cousins. That is, human babies are far more helpless at birth: they are legally blind, have no muscle tone, and are only capable of making smells and sounds that alert potential predators. Compare this to the neonate giraffe, which—only hours after falling 6 feet to the ground from its mother’s birth canal—is capable of galloping.

But I’m getting ahead of myself. Before any mother can rear her offspring, she must first conceive. And before she can conceive, she must find a mate. No problem here, as her very fecundity will send signals to potential mates that scream (“this female is attractive!”) But finding a mate is a problem in the sense that it could be the most impactful decision she makes in her life and the lives of her offspring. She shouldn’t rush her decision about which of her many suitors to pick. In fact, for the sake of the species, females must be choosy. Again, think about what is at stake here: Although there are exceptions (which were exceedingly rare before the advent of modern medicine), women have only one child at a time. Each child takes roughly 40 weeks to gestate and another 18 years until they are somewhat useful (I write this lovingly but bitterly as a father of two teen boys). They are an incredible drain on the physical, financial, and social resources of the mother. And, even though I am a father and I have a bias toward the usefulness of fathers, let’s not kid ourselves: It is the mother who will do the bulk of the work. After all, how many diapers can one father change until they are “even” with the mother for 9 months of even the “easiest” pregnancy?

What does this have to do with beauty? Everything of course. Because females have a choice in mating partner, their preferences for what they find attractive determine which males will successfully pass on their genes. In future posts, I will show how differences in parental investment strategies between and within females drive their preferences for male beauty. I’ll also discuss how the seemingly limitless ability of males to procreate whenever and with whomever has driven their preferences for beauty in very different directions. I’ll also make the case that our appearance as a species and as individuals (i.e., what we actually look like and how that differs from what we used to look like, even as recently as a few hundred years ago) is the result of the mating strategies employed.

But that will take more words than I’ve given myself for this post. Stay tuned.

-The Plague Doctor