Smells like teen romance

Birds do it. Bees do it. Even educated fleas do it. But do humans use pheromones to attract a mate?

Italian honeybee workers and guards gathered at the entrance to their hive (click to embiggen)
Italian honeybees (Apis mellifera ligustica) at the entrance to their hive. Many of the workers are 'fanning', which distributes a powerful homing pheromone from a gland on the bee's abdomen, and also helps to ventilate and cool the hive. (Photo by Ken Thomas, via Wikimedia Commons)
The answer seems to be “maybe”. But if we are attracted by scent, it may have more to do with finding our immune systems than anything else.

 

Studies have shown that we are more likely to be attracted to someone with different immunity to ourselves, presumably to give the broadest benefit to our potential offspring.

To find out more about why some people smell more attractive then others, and potentially how to test you and and your partner’s “olfactory compatibility”, read “The Smell of Love” in Psychology Today.

Pheremones and falling in love

A certain day in February tends to prompt an awful lot of people to wear their heart on their sleeve, so to speak, and declare their true feelings for someone. But what makes that one individual stand out from the crowd to become the object of such a response? Poets and philosophers have pondered this question through the ages,  and in recent times, scientists have set their sights on the issue, too.

An early contender for a scientific explanation of attraction came in the form of pheromones. Pheremones are a group of hormones that are capable of acting outside an organism, on other members of their species. They are present in many species, from invertebrates such as insects, to mammals, and even plants. They are a form of chemical communication between individuals, and may send signals relating to danger, food, or sex.

While they have been recorded in animals, like mice, the evidence that they have an effect on humans is pretty patchy. There have been various studies related to sexual attraction between females and males, but the results are usually  based on semi-quantitative, or descriptive data collection. This generally means asking participants in a trial to rate their reaction on some form of scale. The results from such studies are notoriously difficult to analyse statistically, and any conclusions must be carefully worded to avoid making statements that are not actually shown by the study.

So, despite claims by deodorant manufacturers that they may contain substances that will attract potential mates, no peer reviewed science has been able to back them up just yet, most studies producing conflicting results.

But, is this the only possible explanation for the “Stinks” effect?

As a matter of fact, no. There is another way odor may be attracting potential mating partners. This has to do with the immune system, and is referred to as the Major histo-compatibility complex, or MHC. This is part of the immune system that creates molecules to alert the immune system of the presence of disease causing organisms. The more diverse the range of genes in the MHC system, the stronger the immune system. So, combining two different MHC sets results in stronger offspring.

The idea being that we can potentially smell, and therefore select as partners, individuals with a different MHC than our own. Again, studies have produced conflicting results, one study even suggesting that the contraceptive pill interfered with the identification of MHC compatibilities in test subjects.

One thing is for certain, though. In the modern world, where the majority of people use soap, and deodorant, and wear clothing most of the time, the chances of being able to distinguish between potential partners by smelling them is greatly reduced. Not to mention, socially frowned upon.

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