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So you're into sci fi? But what about sci fact? Sometimes fact is stranger than fiction... Each month our very own Voyager Science Queen* will bring you interesting, quirky and downright bizarre tid bits from the world of science. And its all completely, totally, 100% true! February Sci-Facts |
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“That which we call a rose, by any other name would smell as sweet.” William Shakespeare,
The Oxford English Reference Dictionary |
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The Human Sense of Smell |
| The human sense of smell is weak when compared to that of many animals. Even so, human beings can recognise thousands of different smells. Humans are capable of detecting certain substances in dilutions of less than one part in a billion parts of air. Pregnant women are generally the most sensitive to smells, though you can be trained to detect odours better than the average person; this is an important virtue for perfumers, coffee tasters and wine tasters, and other professionals.
Two small odour-detecting patches carry out our smelling function. In humans, these chemoreceptors are in the olfactory epithelium, which are located high in the nasal cavity. The olfactory epithelium is made up of three kinds of cells: The human nose is in fact the main organ of taste as well as smell. The taste buds can only distinguish four qualities - sweet, sour, bitter and salt -all other ‘tastes’ are detected by the olfactory receptors. Our smelling ability increases to reach a plateau at about the age of eight, and declines in old age; this is one of the reasons why children often dislike strongly-flavoured food that they go on to enjoy as adults. As previously mentioned, women consistently out-perform men on all tests of smelling ability. Although smoking does not always affect scores on smell-tests, it does usually reduce sensitivity to both the sensation of taste and smell, by both destroying the sensitive tissues and by masking the other odours & tastes with tar and nicotine. Some odour receptors have been discovered in human sperm. These enable sperm to swim towards certain chemicals, a reaction called a positive chemotaxis. It hasn’t yet been discovered if similar chemicals are released in the vicinity of the egg to increase the chances of conception. In many species there is a specialized organ inside the nose or mouth called the vomeronasal organ (VNO); humans have a pair of tiny pits in the nose. Fishes, birds, and some mammals don't have a VNO, but the organ is very well developed in snakes and lizards. Scientists remain uncertain whether the human vomeronasal organ is a functional organ or an evolutionary vestige. But the human VNO seems to be the best receptor for pheromones, which are often undetectable as an actual odour. |
| Pheromones |
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So, what is a pheromone, really? In the short version, they are social or environmental chemical stimuli. Usually, they are produced by one individual and detected by another individual of the same species, except in a few circumstances where other animals mimic the scent for their own purpose, such as to lure prey. Typically, pheromones cause physiological and behavioural changes in their targets, some subtle and some overt. These changes are expected to benefit both individuals, such as a female moth advertising her availability to the males of her species, but as previously mentioned, this is not always the case. Pheromones exert their influence whether or not an animal is conscious of pheromone detection; the animal may not be aware that it is responding to an odour. This is usually the case for human beings. The first pheromone was identified in 1956; it was a powerful sex attractant for silkworm moths. A team of German researchers worked 20 years to isolate it. The tiniest amount of the pheromone made male moths beat their wings madly in a "flutter dance" and the scientists used this clear signal to identify when males had sensed the attractant. When at last they obtained the chemically pure pheromone, they named it "bombykol" for the sexy silkworm moth, "Bombyx mori". Human beings do appear to have pheromones. Women subjected to female pheromones tend to have menstrual cycles that coincide. As well, women respond to male pheromones. Women in constant, close contact with men are more fertile than insular or isolated women, with the optimum menstrual cycle for successful conception. You don’t want to know how they collect these pheromones for experimentation. Usually, volunteers wear absorbent pads in their armpits, to collect their sweat, and from this sweat the pheromones are extracted. See, I told you that you wouldn’t want to know. Human beings are dominated by their sight, so that visual cues are more important than olfactory cues when finding another person attractive. Still, the perfume and deodorant industries can try all they like, but they can’t mask pheromones, so your nose may still play a part in your courtship. Happy Valentine’s Day! |
| *The Voyager Science Queen is also known as Lynne Green So, who is this woman who attempts to entertain us with Science? Well, I really am a scientist. I have a Bachelor of Science degree from the University of Queensland, in Zoology. And, at the moment, I am working in a Pathology laboratory. I have always been intensely curious about every aspect of our universe, from the teeny tiny workings of the gene right up to the mind-bending forces that are twisting and knotting inside a blackhole. So, now I am sharing a brain stuffed full of trivia…and hopefully entertaining people at the same time. As well, I write Fantasy stories and novels. One day, I hope to have a book published, but don't hold your breath. Reading is my other major love, and my favourite authors are Terry Pratchett and Isaac Asimov, though I could list hundreds of others. If I had one wish, I ask for more time to write! Read previous Sci-Facts: Indulgence Looking for more scientific oddities? Have you checked out Dr Steven Juan's website? He is, quite literally, the wizard of odds! |
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