Pheromones

I remember hearing about a study where a group of women were asked to rank a series of photos of different men according to how attractive they found them. Once this was done, several of the photos around the median were treated with a pheromone from a boar. Not a person who talks in a monotone about the benefits of superannuation, rather, a male pig. The experiment was repeated several times with different groups of women and each time, the pheromone treated photos were ranked as more attractive than they were in the control group. Unfortunately, sitting here on a Saturday night with a beer in my hand, I have no way of checking if this study is true but for a minute let’s believe it is true and valid because I like the story. This study, if true and not an urban myth, seems to indicate that pheromones, an external signalling hormone, can affect the way we perceive another’s reproductive worth. What is even freakier is that pheromones from a pig are attractive to humans!

This shouldn’t be a shock. For years, human females have been applying pheromone extracted from the anal glands of various animals to themselves in an attempt to be found more attractive. This is where musk originated from. However, musk is a male scent originating in the male Musk Deer, and it seems that women apply this scent to themselves because they find it attractive. Why else would you consciously apply an odour to yourself?  Regardless to whether perfumes come from deer, civet or flower sources the idea behind a perfume is to make oneself more attractive by smelling nice.

Pheromones can be extremely powerful. They can cause extreme behavioural responses in incredibly tiny concentrations. Many animals communicate sexual availability via pheromones and more than just availability, their worth as a prospective partner is also assessed by smell. In humans most of this happens on a subconscious level. First let me preface this by saying that visual stimulation is incredibly important. When you see someone across the room who you  find attractive, it is not their scent that is initially appealing. It is their appearance. The limbic brain including the hypothalamus is often referred to as the emotional brain and is the region that is responsible for your libido. Have you ever wondered why when you meet someone you find attractive you can’t seem to hold a conversation and become a giggling idiot? The visual arousal causes dopamine and many other neurohormones to be released from the limbic brain causing you to feel that rush that is hard to explain but all of us have experienced. Pupils dilate, you start getting sweaty armpits and clammy palms and your body language changes – up to 55% of flirtation according to psychologists, is all in the body language.

Now while your brain is causing this rush of hormones in you, your genetic health is being actively assessed by your prospective partner. They may not realise it but they are smelling your genotype. And you are doing this too in return. Human pheromones are also released at this time of attraction. These are found in your sweat. When you find someone attractive on a pheromonal level it is because their smell is different to yours. We want genetic variation in our offspring and we literally sniff this out. We are seeking a partner who has major histocompatibility complex (MHC) genes (these are important in immunity and I will talk about in the next rant when I start disease) that are different from yours. Studies indicate that couples with different MHC markers are more satisfied in their relationships and are more likely to be faithful. Further, they tend to have less fertility issues than couples who have similar MHC markers.

The type of sweat produced in the armpits and groin is different to that produced elsewhere in the body. As well as being rich in pheromones it is thick and oily. And this is why we have hair under our arms and in our groins; it traps this sweat creating a reservoir of pheromones. This is not body odour. Body odour is caused by not washing regularly and bacteria building up and feeding on this oil sweat. It is their waste products that cause the bad smells and have the exact opposite effect of pheromones!

The genetic compatibility, which is actually genetic difference, that we are seeking in a partner (actually we are seeking this difference in the other parent of our child and often a male partner did not contribute to the genetic make up of the child it helps raise as its own – serious shit. Will rave about this in Unit 4) can be masked causing us to be attracted to a partner we actually aren’t attracted to. Huh? Let me explain. Studies suggest that women who take the oral contraceptive pill have their pheromonal responses skewed. Instead of being attracted to someone with different MHC markers, they are attracted to someone who has a similar MHC odour to themselves. Things move along well until it comes time to have a child. The woman stops taking the pill and, after a bit of time, starts looking at her partner differently, hormonally speaking. And these couples, statistically, are more likely to be unhappy in their relationships, have affairs and have fertility issues.

Actually, an interesting aside, studies have indicated that woman are attracted to different ‘types’ of males depending on where they are in their menstrual cycle. Again, hormones, and again, something I need to look up.

Let’s leave humans for a few brief paragraphs but still stick with sex. In the animal kingdom, pheromones are also used for reproductive purposes. Most of this is common knowledge and is found in all textbooks so I’m only going to talk about finding a mate and I’m going to give to insect examples. A male moth can and does respond to the pheromones of a female from kilometres away. In fact the male silkworm moth can detect a female from 11 kilometres away. I don’t know if there are others who can detect pheromones from greater distances, there most likely is, this statistic just sticks in my head. When they detect a pheromome they fly into the wind and locate the female by small, ever increasing responses of pheromones hitting those receptors on their antenna . And eventually they find the female. Let’s just hope there wasn’t another male moth closer as their mating rituals aren’t quiet as intricate as human systems. Nor are they as fussy. But what I want you to consider is just how much pheromone a female moth can produce – they’re not that big – and how powerful these molecules must be. They have such a major impact in such small quantities.

Wasps also use pheromones to find a mate. Again it is the female releasing the pheromone and the male responding. It works really well over long distances as we saw in the moth example, however, other organisms have managed to use these pheromones against the wasp. These organisms are orchids. Yep, those beautiful flowering plants. Not all orchids but some also use pheromones to have sex, however, they use wasp pheromones. When these orchards are ready to be pollinated they release a pheromone that is remarkably similar to those produced in certain wasps. Male wasps are attracted to the flowers that smell like female wasps and superficially resemble a female wasp. The wasps then try unsuccessfully to mate with the flower. In the attempt the orchid’s pollen sacs are attached to the back of the wasp. Finally the wasp gives up and flies off to find another female. Often this female is another orchid and the pollen is transferred, the plant fertilised and the male wasp remains frustrated.

So pheromones are hormones that work externally and communicate information between members of the same species. Often, the information communicated is about sex. It can also be used to communicate location of food, threats to the colony or territorial boundaries but these are relatively straight forward in concept and are easily understood by reading your textbook.

And to that woman who I am psychologically and genetically attracted to; sorry, I don’t mean to blabber, it’s my pheromones reacting to yours. Makes it sound so romantic doesn’t it?