Since this Sunday is Valentine's Day, I thought love might be a suitable topic. After all, love is all around us. Literally.
Scientists have spent a lot of time studying love from a scientific point of view. This, perhaps, explains the misconceptions about the love life of scientists.
We have determined that much of attraction between individuals within a species is governed by chemical compounds. Not in the colloquial sense where someone might say "they have great chemistry together" but at a more fundamental level.
Animals use pheromones to communicate and one of the things they communicate is an interest in the opposite sex.
Pheromones are found all around us in the air we breathe and smell each day.
We know a great deal about insect pheromones. They are relatively easy to detect and analyze. Determining their effects is straightforward.
For example, the gypsy moth uses a compound called bombykol as its sex attractant.
It is a relatively simple epoxide; one that chemists can easily make in the laboratory. The female gypsy moth releases this compound into the air when she is ready to mate. The male responds.
The response mechanism in the male gypsy moth is so finely tuned they can detect as little as a single molecule of bombykol.
They have been known to follow the scent for as much as five miles which is an awfully long way for such a small creature.
It is equivalent to an adult human walking 500 miles.
Using modern analytical instruments, chemists have determined even some higher order animals use pheromones.
Dogs, for example, respond to para-hydroxymethylbenzoate.
It is the compound released by a female dog when she is in heat.
It drives male dogs wild.
Interestingly enough, it is also a compound used as a preservative in a variety of applications, including moisturizers and such. If you are ever wondering why Fido is so interested in you, check your personal products for paraben.
Pigs have been found to use pheromones. Androsterone is released by males to get sows ready for mating.
Ironically, it is also found in the under-arm secretions of male humans. Why we have pig pheromones in our under-arms is anyone's guess! But that hasn't stopped perfumers from packaging and selling it as a human sex attractant.
We also know our closest relatives, the chimpanzees, emit pheromones called copulins to induce mating.
Given our close genetic similarity, it would not be too surprising to find out humans also have pheromones. Indeed, a great deal of research on the subject would suggest some naturally occurring chemicals induce positive responses in members of the opposite sex.
For example, if women are asked to rate pictures of various men for their attractiveness and then are given a series of T-shirts to smell that have been worn by these men, the T-shirts they find the most attractive tend to line up with the men they find most attractive based on their pictures.
The men used in such studies smell like they look, or they are attractive at both a nasal and visual level.
And as any adolescent male will tell you, smell matters especially around the opposite sex.
This is probably why teenage boys suddenly develop a strong interest in taking a shower on a daily basis.
Some scientists have carried this all a little further. They suggest the whole basis of kissing is for the female to determine if the male smells and tastes right.
A kiss determines if the chemicals that they are releasing are the ones that will provide compatibility and generate healthy offspring.
Our chemical secretions contain markers for the chemical make-up of our immune system. A kiss is a chemical analysis performed at a level below conscious thought.
Ideally, a female is looking for an immune system very different from her own. A very different immune system helps to maximize the probability of survival for her offspring. Kissing is just doing a quick genetic scan to verify a potential mate might be suitable.
An interesting follow up to this is that when a woman has found a mate, the T-shirt odours she then prefers are ones similar to the males in her family - her father, brothers, nephews, etc.
These odours give a sense of security and well-being, a sense of belonging. That could certainly explain the thousands of bottles of Old Spice that appear in Christmas stockings each year.
It is a reminder of dad.
Of course, these are only the chemicals involved in that first stage of human interaction - during attraction.
Other chemicals, such as phenylethylamine, take over during the infatuation stage and a completely different set, including oxytocin, is responsible for long term commitment.
With all of the chemicals queues involved, it is not far-fetched to say "love is in the air, literally."