Your sweat reveals the sweet smells of attraction!
IB Psychology asks interesting questions about the biological origins of attraction in the Human Relationships option; for example: To what extent do biological, cognitive and sociocultural factors influence human relationships?
Way back in the days before I even knew IB Psychology existed I was at university studying Psychology when a friend of mine became interested in the recently published Wedekind et al. study (AKA – The Sweaty T-Shirt Experiment). With a little help from some friends studying microbiology we were able to get some genetic testing done and reproduce an experiment that everyone was talking about. I was to become the guinea pig.
Beauty may not be so much as in the eye of the beholder, but in the nose. Both men and women want to make healthy babies, and that means babies with a robust immune system that fights off disease. Each of us passes on some of our ability to fight disease to our children in our genes and our instincts prime us to choose a mate with an immune system very different to our own. Why? Because that way our children get the best chance of fighting illness. When it comes to these genes opposites attract.
We tried putting these instincts to the test in our university laboratory. Six women and I needed to have our blood tested for 6 genes to reveal what type of immune system we had. If all 6 of my genes match all 6 of a woman’s, that’s bad. I should find her smell unappealing because our children are likely to be less healthy. But if only one or two genes match, that’s good. I should find her smell attractive because it would mean our children would be naturally healthier.
I was to sniff t-shirts worn by each of the 6 women. Each woman had slept in a t-shirt over two nights so it should have been really smelly. The t-shirts were put in a sealed bag and kept in the freezer. We 'scientists' then placed the t-shirts in a jar and next we got sniffy.
On the day, and in the lab I was told that what I was about to be given the t-shirts the 6 women had been wearing. I’m finding it very difficult to believe that this is going to work but I’ll definitely going to try it. Each jar is unsealed in turn and I’m to sniff the t-shirt in it, by taking deep inhalations from the t-shirt jars simply labeled A-F. I start with Jar A and take a deep sniff. I find it to be not nearly as bad as I had expected it to be. Jar B I don’t like quite so much so I place it further down the line than Jar A. I keep going with the jars. Some are definitely smellier than others. Some are not bad. At the end I have 6 jars lined up with the most attractive smells being on the left. Now we want to know if they’re the most genetically different.
A reenactment of the sweaty t-shirt study
The biological origins of attraction
My scientist friend pulls off the A-F labels revealing each t-shirts’ score out of 6. The higher the score, the greater the number of different immune system genes the woman who was wearing that t-shirt has. According to the science behind this, my jars should be ordered with my most attractive smells having the highest numbers and the least attractive smells having the lowest numbers.
What do we find? From left to right, my most attractive to least attractive, the numbers were: 4/6, 5/6, 4/6, 1/6, 0/6, 0/6. I was skeptical to begin with, but this was an almost perfect match to the experimental hypothesis. It was exactly what the science predicted. My top three t-shirts had the stale whiff of different immune system markers and in my least attractive t-shirts I could somehow recognise the reek of my own immune system genes. It appears that opposites really do attract.
Download and read the study below. You can use it in the IB Psychology learning outcome: Evaluate psychological research (that is, theories and/or studies) relevant to the study of human relationships.