I can't find the source, but I read about a study done with women where they smelled sweaty shirts from unrelated men or their brothers or fathers. Across the board they rated the shirts from their blood relatives as smelling worse than the others. The theory was that people with different genetics have different makeups of microbes living on their skin, making them smell different than you.
I like the way my wife smells, and we certainly share no relatives for many, many generations.
I think the concept of “emotional contagion” is a stretch. I simply do not believe that empirically[1], people who smell sweat excreted by frightened people will also feel fear. Disgust as general reaction to all sweat samples is more believable because sweat is generally viewed as an unpleasant smell.
The notion that you are lacking an entire layer of communication when you do not have a sense of smell is also subjective, especially when it comes to those born without it; you can't miss what you don't know. Also other senses tend to compensate, i.e. when some blind people report heightened sense of hearing.
[1] Lack of discussion of sample size makes me think it wasn't representative in size or demographics.
Geekette's concerns are really only validated by the references you give. They have a sample size of 28 and 36 smell recipients, respectively (all likely bored undergrads), which seems hardly representative of all cultures and human behavioral contexts.
It's probably a fair hypothesis that they would not hold up to larger validation studies with more participants and more emotions tested. And to more rigorously interpret what was measured by these experiments, both studies examined fear, which has a well-understood hormonal response (adrenaline, etc.) that is already understood to affect sweat content [1], and one study examined disgust, which as Geekette states is a reasonable default reaction to sweaty odor—enough that this would seem to be a unremarkable emotion to claim was "communicated".
Concluding that humans may communicate other more complex emotions (love, hate, sarcasm, uncertainty, trust, whatever) through sweat is what neurobehavioral scientists love to imply via these preliminary studies and have puffed up by the downstream media, but they are just that: only preliminary.
You bring up sample size here which doesn't really matter because the effect is statistically significant. Your point about the populations being unrepresentative is of course a good point(which can be made about nearly any study, low hanging fruit for criticism) but represents a grave misunderstanding of how science actually happens in the real world. It's absurd to think that you should recruit a representative sample of the entire world to do a preliminary study. Validate on a more convenient sample and expand otherwise it's wasted money and effort.
>It's probably a fair hypothesis that they would not hold up to larger validation studies with more participants and more emotions tested.
There is no support for this besides your opinions and naive priors.
>one study examined disgust, which as Geekette states is a reasonable default reaction to sweaty odor
Did you even read either abstract? This is controlled for. There is a control group inhaling normal sweat without producing an effect.
The problem is you're arguing against a totally different position than where Geekette and myself are coming from. Let's go back to the first lines of the OP: "What are the ingredients of a good relationship? Trust? Communication? Compromise? How about a sense of smell?" ... followed by the statement by Dalton that "Smell is important in social bonding." That last statement there is an extremely broad, confident statement (consider how complicated social bonding is), and it's explained by Dalton with this "emotional contagion" idea.
Two studies that show statistically significant effects for a total of ~60 people smelling odors from two different conditions (fear and disgust) is not nearly enough evidence to back up an assertion as broad as "smell is important in social bonding," nor that a substantial range of emotions spread via odors (contagion). At best, these two studies are suggestive, at worst they are so flawed as to not lend any evidentiary value. "Statistical significance" is not a substitute for critical thought on how much evidence stands for and against the hypothesis (meta-analysis). If I set up two experiments that showed that gravity doesn't exist, p=0.04 for both, would you set aside the totality of the evidence saying it does? Perhaps you would criticize my methods, or the link from my results to my conclusions, no?
You set up a strawman by saying that I'm asking the impossible—that large-scale behavioral cohorts must be assembled for preliminary studies. I'm not. I'm simply expecting some honesty in how people report the conclusions of preliminary studies.
>Did you even read either abstract? This is controlled for. There is a control group inhaling normal sweat
You are incorrect, probably because you did not read past the abstract. Perhaps you should be more careful about telling people how science works in the real world or whatever, because real scientific discussion involves reading methods sections. In the APS paper contrasting fear vs. disgust vs. control, the control condition contained unused compresses, i.e., no sweat at all. From the horse's mouth: "unused absorbent compresses [...] in our view constitute optimal control stimuli because other nonemotional bodily secretions (e.g., sweat from playing sports) can potentially contain other chemosignals."
So... I am supposed to believe that when recipients smelled sweat from the donors watching disgusting videos, compared to no sweat, feeling disgusted at the sweaty odor is some kind of "emotional connection" to how disgusted the donor felt while sweating? Give me a break—this is a sham negative control. The huge confounder, as Geekette rightly points out, is that many people are normally disgusted by any sweaty odor.
The onus is on the publisher to include key data like sample size and cite sources on an article presenting such claims.
EDIT
On skimming the links you gave, I find that the samples and the researchers' conclusion in each study do not constitute representative samples and empirical evidence for this “emotional contagion” theory, respectively. Both studies also focused on only 1-2 types of emotion (fear, anxiety), which cannot be extrapolated to all emotions.
APS published study: Sweat from 10 males + reactions from 36 females.
PLOS published study: Sweat from 49 people (28 males 21 females between 20–37, European origin) + reactions from
28 people (14 males and 14 females between 19–30 years).
I agree, the onus is definitely on the publisher to make sure the claims they make are statistically sound. However you're going to lose most of your casual audience if you focus on the statistics. You need to go to the source for that.
See reply to pak wrt to sample size.
"Support" does not mean "prove". How can you say it doesn't support the idea of emotional contagion when the studies indicate an effect for at least two emotions. Is there more work to be done? Definitely. But these are first steps.
> Disgust as general reaction to all sweat samples is more believable because sweat is generally viewed as an unpleasant smell.
Stale sweat is usually described as horrible. But there are many references to people liking the smell of fresh sweat - see a lot of fanfic for examples.
I know some cite it as a good smell but they are in the minority. Plus, In my admittedly anecdotal experience, I've found that people who say that mean that they like the smell of sweat from people they're already attracted to, i.e. in their partner or in someone they find attractive versus just anybody, which would include people they dislike.
There is also a difference between those liking smell of sweat from the sex they're attracted to and men citing it as a "manly" thing, influenced in no small part by cultural and pop culture messaging.
"In experiments, volunteers who sniffed sweat samples from people experiencing certain feelings, such as fear or disgust, felt those emotions themselves. When volunteers smelled the odor of disgusted people, their lips curled just as they do when smelling something disgusting, says Dalton"
Interesting article. I'm curious as to how much reliable research has been done into contagious emotions. It sounds a bit farfetched the way they describe it in the quote above. The idea is talked about in a Live Science article too [0], but also not much detail is given. I haven't read much about it, but it sounds like one of those single paper non-reproduced ideas that's interesting enough on its own for people to keep talking about it. Does anyone who knows more about this than me have other opinions?
There's been plenty of research on the role olfactory sense play on sexual attraction. It's totally not surprising. If you look at the animal kingdom, scent is a key detector for ovulaton cycles, etc. Here's an old one from NIH ..http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1885393/
Is there any research into how well this works in Autistic people, especially aspergers? Maybe the problem is the lack of ability to smell emotion and people missing this feedback are unable to learn how to spot emotions through other means.
If this were true, people without autism would not be able to apply theory of mind to actors on TV and in movies. Because people with autism lack theory of mind towards others in real life and in media, and those without it have it in both, smell cannot be related. It could play a small role, though.
Don't people with Aspergers lack the ability to understand other people's emotions, rather than lacking theory of mind completely?
It's not just the ability itslf, it's the training it provides. Normal children get a near immediate feedback if they guessed emotions correctly. It's like having somebody with you 24/7 telling you how the people around you feel. Those without the ability don't have that luxury.
For my brother and father it is more like they understand emotions in themselves, and that other people feel emotions similarly, but have trouble identifying them or why they are happening in others because it is harder to take another person's perspective.
Once they know that the person is upset, they empathize and feel bad, so they can in fact understand the person, but they could not guess that there was a problem withoute explicitly spelling it out, and could not derive it from any non-verbal cues.
Here's a BBC Radio Four programme about various forms of anosmia. It includes a woman who can't smell her partner, and she misses that, and realises that smell is often mentioned by bereaved people as being a powerful trigger for memories.
I like the way my wife smells, and we certainly share no relatives for many, many generations.