A smell could kill you

Love and smell Effect of the "Parfum Naturel"

Ms. Croy, did you ask the couples to go to the laboratory and say: so now sniff?

That would be a nice study too. We did something very similar later. What was still the forerunner, however: Two doctoral students, for example, stood in front of the cafeteria or in front of the libraries and spoke to couples who had come out there. So mostly young students. And these couples were asked on the one hand: Are you a couple? On the other hand: how old are you? Can you give us a saliva sample? We needed that. And then specific questions, namely: How good can you smell yourselves? So how much do you like your partner's body odor? How satisfied are you with the sexuality with your partner? How satisfied are you with the partnership? And: would you like to have children with your partner? Independent of each other, of course. So they weren't allowed to see what the respective partner was writing, but rather they should answer as honestly as possible.

In other words, the partner didn't notice if someone said: Well, our sex life.

Exactly.

They took the saliva sample for genetic testing. And if I got that right, in a nutshell: Those who were genetically as dissimilar as possible had a better sex life.

Exactly. In a nutshell, these are the results. We had it analyzed together with the German bone marrow donationwho does this in a daily routine. Of course, we didn't pick out the entire genome, but rather specific markers that are important for immune competence. And the result is that the partners who are dissimilar in these specific brands, that they are actually more satisfied with their sex life, that they want to have children more often and that they generally rate their entire partnership better.

And what does this have to do with immune competence, i.e. with the development of our immune system?

We know from many experiments that the evolutionary mechanism is a very old mechanism which leads to the immune competence, i.e. the health of the offspring, being secured. For this reason: If two partners mate who are as dissimilar as possible, then this increases the chance that the children also have a wide range of resistance to possible germs.

And if it is so strong that we can actually smell it, is it also based on it that we decide whether to start a relationship with someone at all? That means, things like sympathy, appearance, social status don't matter at all?

That of course plays a huge role. You know that too. And that's why all the dating portals work so wonderfully, where none of them give any smell samples. But to put it the other way round: We don't know either - the study situation is also very contradictory - whether people who are actually different are more likely to come together and marry. But what we know from our study is that those who have come together and who are then different are simply more satisfied. In other words, we don't know whether this really has an impact on the partnership, but if you listen to your nose when you choose your partner, you will be happier later.

That means: You can't say why couples are together who are similar in terms of these specific gene markers?

That depends exactly on the factors that you mentioned earlier, and which are of course incredibly important: physical attractiveness, appearance of the partner, voice of the partner, status of the partner or just physical proximity. Most partnerships don't just come about because I think someone is particularly beautiful, but simply because I meet them very often. Work colleagues, for example. It all has a huge impact. And when the body odor comes along and that's right. So I find the smell attractive, then that's an indicator for a good, fulfilled sexuality at least.

What's next now?

We did another study that has not yet been fully evaluated. We invited 50 couples to the laboratory and they sniffed smell samples from their partner and other people. The men sniffed a T-shirt that their friend was wearing and three other women’s T-shirts. And we tried to find out: what is it now that makes this smell attractive, is it the different genetic status? And the men thought it was good if the woman had a different genetic status, but they found it best of all when they smelled their partner. The women, on the other hand, like the smell of their partner, but the different genetic status is most important to them. So men prefer what they know well, women prefer what evolutionarily suits them better.

So for the men who particularly liked to smell their partner, it was also unimportant whether she was genetically similar?

Exactly.

What practical relevance does such a study have? Could dating portals, for example, integrate something like this into their profiles in the future?

I could actually imagine someone trying to do this exploratively. That has a couple of logistical difficulties: It is not that easy to produce odor samples, because when I wear a T-shirt it is contaminated with everything, i.e. fabric softener or the shampoo that I use or the lotion that I am with have creamed. So everything has to be kept stable, it's not that easy. And secondly, odor samples have to be preserved, the best way to do this is to freeze them, and if you send it in the post for three to four days, then it smells like everything possible, but no longer good. That is, it is a bit of a dream of the future, but I could imagine that they will try it one day.

So: when looking for a partner, not only keep your eyes open, but also your nose!