Thursday, October 18, 2007

Bears, Sharks and Strippers

Brick Tamland [opposing women in the newsroom]: I read somewhere their periods attract bears. Bears can smell the menstruation.
Brian Fantana: Well, that's just great. You hear that, Ed? Bears. Now you're putting the whole station in jeopardy.

That little nugget of wisdom comes from the movie Anchorman, but that's not its source. It's often repeated, and likely stems from a bear attack in 1967 that left two women dead and many people speculating that the bears were attracted by menstrual odors. Is there any truth to that claim?

Research has been done on the subject. In 1991, a study was done showing that black bears are uninterested in human menstrual odors. This was done with a series of experiments involving either used tampons or menstruating women in close proximity to the bears. The results showed no preference of the bears for tampons over garbage or feed. There was no preference for used tampons over unused tampons or those soaked with non-menstrual human blood, and no difference in interest with the lower torso of menstruating versus non-menstruating women. In all cases menstrual odors were virtually ignored. For grizzly bears, no scientific studies have been done, but a retrospective analysis of grizzly bear attacks on humans showed that there was no evidence linking menstruation to the attacks.

One place where an attraction to human menstruation may be true is in the polar bear population. In a 1983 study, polar bears both in captivity and in the wild showed a preference for food scent samples or used tampons over unused tampons or non-menstrual blood suggesting that polar bears are attracted to menstrual odors. A brief summary of these studies has been published by the bear management office of Yellowstone National park and can be read here (pdf).

Overall, the evidence indicates that unless you're heading pretty far north you don't have to worry about menstruation attracting bears. The Museum of Menstruation and Women's Health backs up that claim. What if you're into SCUBA-diving instead of hiking? Sharks are notorious for their attraction to blood in the water. The Museum of Menstruation has something to say about that as well: "many women fear that this discharge may attract sharks. The truth is that women divers are attacked by sharks less often than men are." However, there could be a number of reasons for this difference, and whether sharks are attracted to menstrual bleeding remains inconclusive as no controlled studies have been done. There are arguments to be made for both sides, as discussed here, but the consensus among divers, at least, is not to worry about it.

So bears are indifferent to menstruation and we're unsure about sharks, but what about people? There are behavioural cues, but no solid data regarding pheromones. Other phases of the menstrual cycle are better studied, including the time of maximum fertility just before ovulation. Many studies have shown that women at this point in their cycle, 'hidden-estrus', appear more attractive to men by a number of different metrics. (Some studies were mixed-sex and women found them more attractive as well!) This can be accompanied by other behaviours, such as men being more attentive or protective of their partners. The effects of 'hidden-estrus' signals on male behaviour is highlighted in this recent paper in Evolution and Human Behavior. In this study, 18 strippers reported their tips and menstrual cycle over a period of 60 days. It was found that among normally cycling strippers, peak tip earnings occurred during 'estrus' compared to the luteal phase which, in turn, were higher than during menstruation. This difference disappeared among strippers taking birth control pills. A deeper discussion of the paper can be found over at Pure Pedantry. For people who may not be familiar about the inner workings of a strip club (or, as the authors put it, "Because academics may be unfamiliar with the gentlemen's club subculture...") the paper even includes some background on the US stripping industry that alone is worth the read. Despite it's inherent humour value, this study could be a jumping off point for some interesting discussions about human evolution and behaviour. Have humans actually lost the 'estrus' phase, or is it just better hidden than in animals? What are the evolutionary advantages? Or it could just be an excuse to do more science in a strip club.


Anonymous Coward said...

It's all about the breasts . Apparently breasts of lactating woman, make other woman horny.

Anonymous said...

Basically the punch line is to save some crucial cash it's all about the post menopausal strippers.
Besides they have all the best moves from the 70's.

Bayman said...

I don't get it. Are these studies supposed to have something to do with science? Is there some implication for human evolution, biology or reproduction? Or is this just a bunch of guys with the maturity of 13-years olds who think it's funny to say things like "MENSTRUATION!" HA!, "ESTRUS" HA HA! "STRIPPERS" HA HA HA! Hilarious!

Kind of lame. Maybe I'm just a stiff, but I don't really see the "inherent humor" of stripper's menstrual cycles, or anyone else's for that matter. Menstrual cycles are one of the most fascinating aspects of reproductive biology and the key to human existence, not something to laugh at or be disgusted by.

Assuming the goal of these papers was to actually study human evolution or biology in some way, hanging out in strip clubs seems like a pretty dumb way to do it. Strip clubs must be the most socially-contrived expressions of repressed sexuality one could find. You can bet that most of the clientele aren't getting much action and the women are there to make money. Not much to do with reproduction or evolution.

Maybe people who are interested in sexual biology should just study the actual sexual habits and practices of humans instead. Then again, most of that science has probably already been covered.

Anonymous said...

I think Bayman is PMSing again...

kamel said...

The 'inherent humour', for me at least, was the image of guys in lab coats heading to the rippers to do some science (which was, as you point out, probably not their primary concern) or, more generally, the contrast of science being done in such an 'unscientific' environment. Juvenile? Maybe, but we're all prone to that from time to time.

I agree that this study was probably designed for the "shock"/headlines it would generate (or, as one blogger covering the story described it, 'mind candy'). It seems to have acheived it's goal, having been cited and discussed in blogs and news outlets of varying repute. The superficial approach they took was was that while other studies have suggested that 'hidden estrus' is detectable, can it be applied to a real human behaviour? While strip clubs may be contrived expressions of repressed sexuality, going to them is still an actual human practice. Earth shattering? Unlikely. I doubt we'll start seeing strippers altering their shifts or going off the pill to maximize their tips, or beer commercials conciously using only using women during that phase of the cycle because they seem more attractive.

Maybe it wasn't the best (or most tasteful?) example to use, but the underlying idea of this and other studies is that up until recently the scientific consensus was that humans were unique in that they had a menstrual cycle with concealed ovulation - in contrast to other mammals which have an estrus cycle and advertise fertility with visible cues (eg. 'heat'). There has been growing evidence that estrus in humans isn't quite so hidden and can be detected, though the idea remains controversial.

So the questions, I suppose, are 1)Is 'estrus' hidden in humans? (is it something that unites us with the rest of the animal kingdom, or separates us?) 2)If estrus has been lost (hidden), what is the evolutionary rationale? The paper cited above tries to address #1 (in it's 'headline grabbing' way). Whether it succeeds or not is up to the reader.