Saturday 15 September 2012

Of Mice and Men and Nipples and Supernumerary Nipples

If I can be allowed a Judaeo-Christian metaphor, there's a Devil in me that makes me wish I could shock the Biblical fundamentalists out of their confined intellectual spaces. So, I was thinking. If I can be allowed to think of myself as a subversive archaeologist, then I can also be a subversive anthropologist. Makes sense, don't it? Well, in the spirit of subversion, and remembering the likes of Casey Luskin and what I've said about his lameness before [here and here], tonight I'm letting the Devil out. Here goes. *wolves howl in the distance, a chill wind whistles up the leg of your Land's End cargo shorts, the crickets cease their normally incessant, but in these circumstances oddly comforting until they stopped, chirping*

A wise teacher once pointed out to me that one of the reasons many people don't understand evolution is that it is one VERY BIG subject. Anthropology embraces evolution, and it behooves undergraduates studying anthropology [at least in North America] to learn about human evolution-- DNA, and inheritance, and genetic variation within the human species are at the core of what used to be called physical anthropology, but which is now alternatively known as biological anthropology. One of the coolest things about anthropology is that it is the only discipline that seeks to understand human beings holistically, through the study of their physical and cultural makeup. So it's not such a leap for me to think of myself as a subversive anthropologist.
     But, back to the deviltry. I think it's quaint that fundamentalists spend so much time fretting about the fossil record when there's so much evidence of evolution in the here and now. And, when it comes to evolutionary anthropological shockers, I've got a million of 'em. My purpose today is to remind the reader that men have nipples. Have you ever wondered why? And, why do some men and women have more than two nipples, like the dogs, cats, cows, and other mammals that have litters of young? Roll that idea around in your head for a minute. [Actually, when I told one of my co-workers about the 'condition' known as supernumerary nipples, it almost made her gag!] Best of all, they're not really so rare. Don't believe me? Watch, and learn.
The eye can't lie, and in this case neither does the camera (photo source)
So, hypothetical Creationist person to whom I'm talking, whadda ya make o' that? If it isn't weird enough that men have nipples, what is this guy doing with more than two [presuming, of course, that there's a mate to the larger of the two in this image on the other side of this guy's chest]? And it's not just a 'guy' thing. Have a look at the young woman in the photo below, who clearly exalts her additional nipple.

Places where extra
nipples can occur
     Such conditions as supernumerary nipples are the result of the expression of genes that persist in the human genome, but which have been 'turned off' during our evolutionary trajectory [for the fundamentalists among you, that would be a reversal of evolution--something that would be intuitively impossible if there was no such thing as evolution]. The 'turning off' of a gene or genes happens usually because the structure has become atavistic--no longer necessary. And since it's the case that in biological terms, tissue of any kind is 'expensive,' and it's a waste of good energy to make unnecessary structures. As far as we and the other mammals are concerned, the number of nipples more or less accords with the size of the litter. Because humans usually bear only one offspring at a time, the genes involved in producing multiple pairs of nipples have become vestigial, and under normal circumstances have ceased expressing themselves in the organism. But once in a while a tiny error in DNA replication during sex-cell production results in expression of a gene or a complex of genes that code for one or more of the ancient auxiliary pairs of nipples. Simple! Don't you think?
     That takes care of supernumerary nipples. But why do men have nipples in the first place? Surely God could've designed nippleless males without even blinking. Although, come to think of it, the old guy seems to have taken a lot of short cuts when he was specially creating us and the rest of life. [I don't need to remind you, for example, that giraffes have the same number of vertebrae in their necks as we do. I've heard of deities cutting corners before now. But few ever consider just how little original thought the Abrahamic god put into making the back-boned animals different from one another, whether we're talking about fish or Finns. I mean, really! Couldn't whales, bats, people and moles have been given different numbers of digits at the ends of their front limbs--or, if you prefer, fins, wings, hands and paws?] But I digress.
     Men have nipples for the same reason both males and females have gonads--these structures underpin reproduction--and the structures themselves are formed early on in the embryo, often long before parturition. Sure, sure, everybody knows that the embryo is destined to become male or female from the moment of conception. However, the process of sexual differentiation is time-transgressive in the developing organism. In the case of nipples, by the sixth week of gestation a pair (usually) of sweat glands in the chest has begun to differentiate as nipple tissue. But, and this is important, the point at which male and female embryos begin to develop along different lines doesn't occur until the end of the same week in which the nipples develop. That's why both sexes have 'em, even if only one of the sexes ever puts them to use as anything other than an erogenous zone. And, as we all know, in the general case, visible differentiation of breast tissue doesn't occur until puberty, and breast maturity in females isn't complete until she's had offspring and has nourished the newborn with her milk.
     I could rattle off a half a dozen more examples of shocking evolutionary tidbits without breaking a sweat. But I'll leave you with just one. And, feel free to share this with your creationist/intelligent-design-adhering friends. Then watch their eyes glaze over. But let them know that next time I talk about this stuff, it's gonna be about genetic variation in the genitalia. That's gonna be fun.
I think I've pretty much beaten this one past death. So, I'll go on to something near and dear to my heart [and, if you're a real archaeologist, I know it'll be dear to yours as well].
     I'm home from work, and it's Friday. I'm enjoying the cool of the evening with all the windows and the door open. Luxury. It's Hell living in Heaven [more Judaeo-Christian figurative language for which I hope you'll forgive me].
     Let's see.
     What'll it be?
     Ahh, here we are.
     Tonight's drop of straw-colored nectar is going to be a Motos Liberty 2008 Chardonnay. Curious label motif; wonderful, juicy, lightly oaked. The label says it's 'cellared and bottled' in the Napa Valley, California. That leaves the fruit's origin a little vague. But there's nothing vague about the liquid inside. Round and perfectly dry. A hint of pain grillé as the French would say. Buttery, but not too. Citrusy [lime and cumquat, for the most part]. Yum.
     If you live in the Surf City area it's on for a very good price at U-Save Liquors on Mission Street. Hell, if you're that close, drop by and we'll have some together!

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