Apparently more men are shaving their armpits. Apparently this is a “thing”. If it is a “thing”, I really hope it wasn’t brought into fashion by these guys:


(You SHOW those shaved pits there, honey)

Anyway, the question becomes…why shave your pits. It might interest you to know that humans have a relatively high amount of pit hair compared to other primates. We’re mostly hairless, but we’ve got more hair there. Naturally, scientists start wondering why (you know you’re a scientist when you look at that picture up there and think to yourself “hmmm…why does he shave his pits? What EFFECT does that have? I should test this…”). And scientists start thinking of smell.

Smell (in this case the scientists call it ‘chemical ecology’) has become a big thing recently in studies of humans. Do we smell only what we consciously smell? If not, what DO we smell? And WHY? Do we sense “phermones”? Studies of male sweat and women sniffing it and studies of female strippers in the luteal phase have abounded. And the current answer appears to be…we don’t know. There are no yet identified chemicals that could count as phermones. Studies of women sniffing men’s sweat have shown effects in what they prefer, but is that only a function of menstrual cycle, or is it a function of something they’re smelling? Whatever it is, we don’t know what we’re smelling.

But we do know we have a lot of armpit hair. And one of the things hair does is trap odorants (doesn’t your hair smell nice with all that new shampoo?). And if you’ve got hair in your pits…well you’re going to trap odorants from your pits. And if you DON’T have hair in your pits…well what happens then!? Scientific minds want to know.

Not only that, they want to compare it to the smell of a beaver’s butt.

Kohoutova et al. “Shaving of axillary hair has only a transient effect on perceived body odor pleasantness” Behavior, Ecology, and Sociobiology, 2011.

So how do you study whether pit hair influences the smell of your pits? My friends, it is time to shave your pits for science!

They started with four groups. All of them comprised a group of men, half of whom had never shaved their armpits, and half who had been shaving their armpits basically constantly for about a year or more. They had some of the guys stay unshorn as controls, while the rest shaved their pits for science, even though half of them had never done so before. Some of them were then allowed to regrow their shorn pits, while others had to continue shaving throughout the experience. Right after shaving, and at weekly intervals up to 10 weeks afterward (to achieve full regrowth), the dudes wore cotton pads on their armpits for a 24 hour period, and then turned them in. During this time, they were told to avoid

(1) using perfumes,
deodorants, antiperspirants, aftershave and shower gels; (2)
eating meals containing garlic, onion, chili, pepper, vinegar,
blue cheese, cabbage, radish, fermented milk products, mar-
inated fish; (3) drinking alcoholic beverages or using other
drugs; (4) smoking; (5) sexual activity; (6) sleeping in a bed
with a partner or pet. Whilst wearing the pads, they were
also asked to avoid intense physical activity (e.g. jogging,
playing football, etc.).

They were allowed to shower using nonscented soap, except for the shower directly before the sample, when they had to wash with only water.

This doesn’t make a lot of sense to me. The food, alcohol, drugs, pets, partner, aftershave, etc I completely understand. But WHY. WHY did they SHOWER? After all, if you’re going to be looking at the effects of shaved pits vs non-shaved pits on body odor…wouldn’t you want them to build up some BO? Washing with soap every day is going to get rid of the odors and the bacteria producing them, at least temporarily. Seems like you’d be…washing out the effect if you know what I mean.

Anyway, the dudes handed in the pads. Then they led the ladies in. For three of the experiments they used women on birth control (in an attempt to control the hormonal cycle), and for one they used normally cycling women. The ladies sniffed intensely at each sample, sweat, and controls. Of course you have to have controls! And they wanted to pick something natural you know? So one was cinnamon, and one was castoreum. Castoreum, far from being one of the popular relaxing scents featured in fashion magazines…is the scent from the anal gland of a beaver. Did they want something kind of close to what the dudes smelled like? DO dudes in fact smell like beaver butt? I really think I want to know.

The ladies sniffed away (men’s sweat, and beaver butt, and all they got paid was a CHOCOLATE bar for their trouble. That’d better be some good chocolate, amirite?), and rated it according to intensity, pleasantness, and attractiveness (on a scale of 1-7, not surprisingly, none of the scores ever got much above 3 for “pleasantness” or “attractiveness”).

Anyway. The girls sniffed. And they rated.


(This is the schematic for the experiment, showing the armpit shaving scheme. I found it almost impossible to make out. Sadly they never explained what they were doing in words)

In the first experiment, they found a significant effect. The women on birth control rated men’s BO more pleasant if they had shaved pits. Unfortunately…that was it. They were never able to replicate the results in any of the other experiments, and the only odor that came out significantly MORE pleasant was…the cinnamon (though one group rated the beaver butt odor as pleasant. I really want to know what that smells like). Unshaved pits smelled the same as shaved pits, and regrowing pits also smelled the same. Like pits. They looked high and low for differences. They compared weeks. They compared the left and right pit. They used dudes that had never shaved before and dudes that shaved all the time. Nothing. It all came out in the wash. The authors conclude that shaving status of men should be checked for smell studies…but that’s about it.

Sad shaved dude is sad.

All that work for nothing.

Now, the scientists really did try. They controlled everything so carefully. Dudes who had never shaved vs dudes who did, newly shorn dudes vs those who weren’t, regrowth on the same guys to control for timing. Women on birth control and women not.

But why. Why did they shower. I bet that rinse off with cold water easily destroyed any of their effects.

And one more thing. WHY did they do this in MEN!? I mean, maybe, as they speculate, the trend for men shaving is “growing”, but let’s be honest, women are pretty much expected to have no hair there. Since it’s so much more common for women to have hairless pits, I’d be far more interested to see what effect this had, rather than the rare truly hairless man ape coming into my line of sight at the gym. They attempt to justify not using women because they didn’t want to have to control for menstrual cycle. Me, I call that lazy.

But anyway, dudes, if you’re contemplating shaving…well first, try and make sure you do it for science! And secondly…don’t expect much difference. Sorry, but we ladies just can’t tell.

Kohoutová, D., Rubešová, A., & Havlíček, J. (2011). Shaving of axillary hair has only a transient effect on perceived body odor pleasantness Behavioral Ecology and Sociobiology DOI: 10.1007/s00265-011-1305-0