Potentially Inappropriate Posts Part 1: Human Sexuality, Addendum

Tengu commented on my first human sexuality post and pointed me in the direction of very interesting study asking much the same question I did. Why do human females have perpetually large breasts? The study is illuminating, but leaves a few questions unanswered, though I encourage you all to read it. First of all, the authors argue that large breasts got women in hunter/gatherer societies through tough times--they basically acted like camel humps (fat stores). Well, here's my question: why the breasts? They offer tenuous evidence that breast fat somehow converts to milk, but I'd like to see more on that. The human body stores fat in all sorts of places: thights, butt, belly, and breasts. But why would natural selection drive fat stores for women only to the chest?*

Second, it large breasts were so important for early societies, why aren't they strongly written into modern human genomes? The fat-store theory is great, but it implies a pretty strong evolutionary bottleneck--you did not survive the dry season without big breasts. So you get to modern society and women like Amanda Beard** (an olympian swimmer) crop up. Again, I voice a question I asked before: If large breasts confer any kind of advantage, be it for sexual selection or natural selection, why aren't large breasts the standard?

Although, I guess I can't know that for sure. Somebody would have to run one helluva study to figure out the "average" breasts size among various populations of women. Would that average change across traditionally "racial" or culture boundaries? I just got a cool book which features Playboy centerfolds for 54 years, from 1953-2007, and intend to figure out the average myself, leaning on the assumption that Playboy is an accurate barometer of the "American Girl." What I'm finding difficult here is that measurements are not always known and are sometimes simply incorrect, so...yeah***. This is a story for another day, though.****

I don't really see a reason why large breasts can't be the result of both sexual selection and natural selection. It would be advantageous for men to find a naturally selected feature attractive, as it would more quickly disperse that trait among the gene pool. Look at the whole mess of display organs in animals. Dimetrodon has a giant dorsal sail that probably functioned as a thermoregulatory device but could have easily functioned for sexual signaling. Modern giraffes have long necks for both reaching high vegetation (and thus neatly avoiding competition) and battling with rivals. Triceratops had horns and frills that have been shown to have intraspecific display/battle functions, but you can damn well be sure that it's gonna defend itself against a marauding tyrannosaur with that same weaponry. A single structure can have multiple uses.

And another reason why small breasts might successfully "infiltrate" any sort of norm could be just the fact that our genes are spread extremely far, and a whole host of new phenotypes have popped up as a result. And thanks to the same mechanism, no matter what the phenotype, somebody will find it attractive (on a man or a woman), so it successfully remains in that population's gene pool. Anyway, go ahead and read the article, and post your thoughts below!

*And if large breasts are such an advantage during the dry season, why wouldn't other non-human primates develop them?

**Amanda Beard might be a poor choice. Atheletes tend to lose every inch of body fat, especially olympians. Ms. Beard might have had larger breasts before diving into the pool. She's just the only example I could come up with on a whim.

***Playboy likes to pretend the breasts don't get much larger than a DD. There are only four, maybe five examples of playmates with cited busts of DD, and I question whether these measurements are actually too conservative. I could list some names, but this is honestly a topic for an entirely separate post.

****Yes, my wife is aware of the book. She thinks I could publish such a study in a social sciences journal.

Potentially Inappropriate Posts Part 1: Human Sexuality, Part 2

Yesterday we discussed how women are the peacocks and men are the peahens in terms of who is wooing who in the species Homo sapiens sapiens. I attempted to demonstrate that one of the "big guys" that women have for attracting the opposite sex are her mammary glands (exemplified by Salma Hayek, to the left). Well, let's talk about that...er, those.

Most mammals have more than two "breasts." In fact, it's difficult to call what most mammals have "breasts." Most mammalian females have multiple nipples connected to mammary glands that swell with milk when babies are around. Mammary glands are a defining character of mammals, of course. They began their evolutionary history as modified sweat glands--a form retained in monotremes. In other mammals, mammary glands expanded to include several distinct nipples. Have you ever seen a big momma pig on her side with a dozen piglets suckling happily? In every non-human primate, mammary glands are specifically for feeding the young. Male pigs don't get all excited when they see a big mammary gland hanging from the belly of a sow. And male non-human primates could care less about female breasts, even when those glands are swollen. Monkeys and apes are more...well, ass-men. The female posterior swells during estrus and the males start hootin' and hollerin'.

But human females are the only mammals with perpetually swollen breasts, leading most to conclude--quite rightly--that breasts serve an important secondary function. As I said before, they're the equivalent of ceratopsian neck frills. It's hard not to swivel your head when a girl like Salma walks by. But here's a question for you. Has the advertising power of breasts overpowered the baby-feeding role? That is, among human females, is nursing now the secondary purpose of breasts? Is showin' them off the primary purpose?

Breast implants show up pretty early in American girls. Sue Williams was the first Playmate to have implants--in 1965. However, breast enhancement wasn't the safe science it is today. Silicone was injected directly into the breast tissue, often multiple times. This led, invariably, to cancer in many women. Later implants were considerably safer: saline implants preceded silicone gel implants. Both have their own set of problems, including the risk of rupture and the sometimes-hideous visual results. Breast implants are invariably tougher and thicker than breast tissue itself, and although they may be visually attractive, people tell me they're not all that fun in...the...sack. And there's another gigantic downside to breast implants:

In some cases (this depends primarily on the implant's size), breast implants impede the ability to nurse. Did you hear that? In addition to the health risks caused by the surgery, the foreign material in the body, and the recovery afterward, you might not be able to nurse your babies!

But why do women get breast implants in the first place? Two primary reasons, I think:

1) Attract the opposite sex, and;

2) Reconstructive surgery after damage to the breast because of cancer or injury (or masectomy).

The first reason is undoubtably the most common. And think about it--that's a helluva gamble. Your risk your own life on the surgery table in hopes of attracting the opposite sex, which reproductive drive tells you to mate with and procreate, but then, hold on--you might not be able to feed the baby! That's...incredible! Breasts have switched from being primarily for feeding babies to attracting mates. No other animal does this! But again, I ask about technology and medicine. Certainly breast implants would not be as popular were it not for advances in medicine that make them safer. What's more, women don't always feed their babies with their own breastmilk. There are wet nurses and bottles for that. Of course, both are potentially inferior, as the mother's milk passes on important immune agents to the baby. It's that crazy? It boggles my mind, honestly. We're so happy with our technology and medicine that the very organ that makes us mammals is losing its defining purpose. That's epic stuff.

Potentially Inappropriate Posts Part 1: Human Sexuality, Part 1

I like dinosaurs, gaming, paleontology in general, movies, very few comics (mostly webcomics at this point), H. P. Lovecraft, and...wait for it...women. I know, I'm a bad person. But don't worry too much, it's not a "ooh, boobies!" kind of thing (although there's some of that, too). Modern man has some backwards sexual tendancies compared to most of the rest of the vertebrate community, especially other mammals or, heck, non-human primates.

And it's something that interests me. Time to be totally up-front here: I'm a breast man. Thus, the picture at left (Denise Milani). I also prefer an hourglass figure. I don't think these are bizarre human male tendances. They must mean something, right?

But why do I like breasts and an hourglass figure while my friend Luke likes legs and a tone midriff? Why does my friend Erik like butts and...a tone midriff? Why do both of them (and some of my other friends) prefer smaller breasts?

In a total reversal from most other vertebrate animals, it is the females of Homo sapiens sapiens that are the sexual "billboards" (in general). Big breasts, long legs, tone midriff (don't understand that one), bubble butt, these are all desirable traits. But in most non-human vertebrates, males compete for females by being billboards. Ceratopsians had giant frills and big horns. Male elephant seals are enormous, blubbery, and have trunks. Male baboons have bright faces and giant canines. Male birds of paradise are ridiculously colorful and have bizarre plumage that's useful only for attracting the opposite sex. But women have breasts, butts, and legs, which they show off with swimsuits, low-cut tops, and short skirts. Men can do the same thing, but the opposite effect is usually achieved: no woman I've ever met likes a guy with super-huge muscles, for example.

Another interesting reversal is the breasts themselves. In non-human primates, breasts are used primarily to nurse the young. Males are attracted to the females posterior when it becomes swollen during breeding season (that's estrus). Humans don't really go through a visible estrus cycle (although that's debatable), so the butt was replaced by larger breasts. But there's a tradeoff here--breasts don't just swell and shrink depending on the season. They stay large! So human females are essentially advertising their sexuality all the time, and clothing is used to openly advertise it or not. Men, however, do not have such obvious sexual organs. Facial hair may be the male "billboard," but it doesn't have the same draw as...well, Denise up there. In Homo sapiens sapiens, the females are primarily competing for male attention instead of the other way around.

You can see this yourself by going to a bar or pool hall on the weekend. Men dress casual, in T-shirts and jeans, but women use perfume and revealing clothing to attract attention to themselves. If men and women were peacocks, the sexes would be reversed! The females would have big showy feathers, and males would be duller-colored.

But here's where another question comes to mind: Are there universally attractive female features? Clearly not, as a quick survey by my friends reveals. But why is that? You don't see that kind of selectiveness in non-human animals. Female moose are going to mate with the toughest male with the largest antlers. Although my field experience in close to nill, I would think that females aren't saying to each other, "You know, I really like a male with big kneecaps." Females like antlers. Protoceratops females liked vaulted nasals on their males and big frills. Yowza! So what about humans? Why don't males across the species harbor similar desires for certain female features? Let's say that hourglass figures are an indication of fertility (which has been theorized!). Why would any man prefer a woman with anything but an hourglass figure? We could say the same thing about breasts: let's assume that large breasts are an indication of increased milk production (as has although been theorized). Why would natural selection favor anything below a C-cup?

Could this be an indication that natural selection isn't working in humans like it used to? Because medicine and technology keeps us all alive and breeding, those phenotypes which would otherwise be "bred out" of the gene pool stick around, and when you get to 6 billion+ people, sexual preference among males is also going to expand, too. Maybe when humans were hunting bison with spears and living in caves, sexual selection was more strongly universal, but as populations increased and lifespans lengthened, those factors were toned down. And today, you have every body type imaginable wandering the planet, and everybody will find somebody thanks to the miracle of overpopulation.

But there is still a very strong tendancy for women to be the "advertisers," which is interesting. I also wonder if, besides having a biological component, cultural factors differ between distinct human populations (more on that in future posts) in terms of who is competing for who?

More on this point in a future post. Feel free to call me a jackass in the comments, but this is interesting stuff. I like placing humans in the same scientific context that we would any other animal!

Important warning: If you're a woman, and you're wearing a low-cut top or a bra that emphasizes your cleavage, and you meet me, you'll have to excuse my descending gaze. I know your eyes up "up here," but goddamnit, it's not personal! Also: Don't avoid said types of clothing on behalf. :-D