Humans Are Smelly: If there were any around, they would be.
But it’s hardly unique to them. All primitive species are: because it’s a consequence of advanced species (and especially those who take their cue from our friendly local aesthetes) investing in both much improved senses of smell plus excellent personal hygiene via biotechnology and nanotechnology. By the time you have skin that dirt literally won’t stick to, sweat that smells of roses and avoids supporting bacterial growth, and even shit that literally doesn’t stink… well, everyone not comparably enhanced is a stinky ape.
Or stinky lizard, stinky slime mold, stinky bunch of tentacles, whatever.
It is, however, considered polite not to point this out. It’s no sin to be primitive. Now, if it’s by choice, on the other hand…
I will point out that humans only smell from two sources, the joint areas of the body, and the anus. The rest of the body is scentless. And that bacteria on your body? A good portion of that is “good bacteria” that acts as the first line of defense against infection and disease.
Just because apocrine glands are concentrated in certain areas doesn’t mean they’re absent elsewhere – and remember, this is to a certain extent the product of an enhanced sense of smell. Baseline humans are pretty nose-blind relative to much of the animal kingdom. I suspect the average dog doesn’t think that the rest of the body is all that scentless.
(The mouth/breath is also a large contributor to human smell, along with things that aren’t strictly speaking human smells but which accumulate on us and aren’t cleaned off naturally, only by bathing.)
I was somewhat unclear with regard to not supporting bacterial growth: what I intended is specifically engineering out, say, feeding skin-resident anaerobes with sialomucin, whose proliferation is a major contributor to body odor.
(In general as well, of course, part of serious biotech augmentation work is seizing control over one’s microbiome, skin flora and intestinal flora both, given the large effect it plays in one’s biology. It’s safe to assume in this ‘verse that transsophonts’ microbiota is probably augmented just as heavily as they are themselves.)
Not nearly as much as you’d think. We just don’t do much that needs us to actually train our sense of smell, and we’re socially conditioned not to do the sorts of things that animals do in order to make the most of their sense of smell.
As one researcher pointed out to me in the past; if it were customary to greet everyone you met during the day by thrusting your face into their groin and taking a good long whiff, you’d soon learn all sorts of fascinating things about people’s health and wellbeing and what they’d been doing.
Clothes also obfuscate a lot of the information that would otherwise be conveyed by olfaction, too.
It’s a relative thing. If your sense of smell is a millionth as acute as a dog’s and a seventy-millionth as acute as a grizzly bear’s, then the canids, the ursids, and the people who pirated their olfactory systems get to call you nose-blind.
(In the same sense that anyone whose visual system can pick up anything from long-wave radio to gamma rays may fairly sniff at we “blind” souls who can manage a 300 nm range on a good day.)
Apropos of nothing, I’m now (trying to stop) imagining the hilarity that might ensue were a diplomatic delegation from just such a culture to meet with the Imperial Couple for the first time.
So, a little bit late to follow up on this one, but a few more things did occur to me. The original trope has some pretty big assumptions underpinning it, namely:
That the other alien species you meet have a sense of smell (or taste, as appropriate for the medium you’re meeting them in).
That said alien species sense of smell/taste actually encompasses the volatile chemicals your damn dirty ape body is producing.
That those alients have a notion of “offensive smells”. Plenty of species on earth have big brains and no aversion to poop, for example. Many (but not all) notions of bad smell that humans have are learned, and different cultures might not have the same aversions.
That somehow what you smell of is related to something that a being of a potemtially radically different biology (or even geology) is likely to find unpleasant.
The stinky humans trope seems pretty much inextricably linked with crinkly forehead aliens, in terms of plausibility.
(though I have now had a slightly silly vision of an alien whose reaction to humans is a bit like the reaction of cats to catnip… lots of hugging and snorting and rolling around followed by running off and hiding in a dark place, tripping balls)
Seconding this.
(One of the questions I was tempted to ask but didn’t at the time of posting was, “But what if you like the smell of that one species’s unadulterated biological musk that everyone else is complaining about — and you find everyone else’s smell (or lack thereof) intolerable?”)
To take those in rough order:
Small (molecular weight < 300) and thereby appropriately volatile molecules is a relatively limited set of molecules. While there is unlikely to be perfect correspondence, there is virtually guaranteed to be overlap. (And specifically re humans, note that such common stinky-human compounds as trimethylamine, indole, skatole, fatty acids, and odiferous steroids are both molecularly trivial and/or building blocks likely to appear in the evolutionary local optimum that is carbon chemistry.)
None of them, however, are sophont species. Now, whether or not you would agree with the notion that civilization is measurable by the distance we put between ourselves and our shit, every species is likely to discover the value of tabooing their own (and to a lesser extent, other critters’) entropic waste products as a matter of public health shortly after discovering the local version of germ theory, if they haven’t before. Once learned, easily generalized.
While this does not by any means eliminate the possibilities of Mr. Catnip or the species whose sweat smells sweet as apple honey, since these things do tend to be learned, except in unfortunately coincidental cases, such reactions are much more likely to attach to pheromonal musk or other such things rather than waste products. Even if you do happen to urinate all 25 aromatic molecules that make up the fragrance of chocolate.
(Also note that for various reasons, strong scents tend to be considered unpleasant per se even if they would be pleasant in milder concentrations.)
(I’ve no idea why the numbered bullet points that were in my original post got smashed flat like that. There’s obviously a trick to bulleting on this blog engine).
(A) Well, yes, this is kinda true, except that there are species who’s sense of smell/taste is so atrophied it isn’t always clear it is there at all, and when it does appear to function it is massively attenuated. Toothed whales and birds of prey spring to mind.
(B) There are some assumptions there about the biochemistries involved, and the associated temperatures and pressures, but I’ll concede that things that share an earth-like environment and have carbon biochemistries will probably be able to smell each other, if they can smell at all (see above).
(C) There’d be some interesting social changes requirted for some species, there. Any that use poop as a social signalling system, for a start, and also any that consume caecotrophs. It becomes increasingly awkward to avoid effluent if you’re a water dweller, too. In any case, a learned aversion to an evolved trait seems less likely to create a strongly repulsive reaction; I know well that the end products of glycation are quite carcinogenic, but that doesn’t stop the smell of cooked donuts or meat being attractive. If your species spent a few million years eating carrion, a few hundred years of medical enlightenment might not switch off the bits of your brain that link the aroma of rotting flesh and exploded digestive tract with the concept of mealtime.
(D) Whilst you are largely correct, and my example was not intended to be serious, I have three words for you: Anal Scent Gland. Even the word you’ve used, musk, has its origins in something generally secreted from glands in that area. Social signalling via poop and rubbing butts on things is pretty common, after all.