Jacobson's Organ by Lyall Watson

Author:Lyall Watson
Language: eng
Format: epub
ISBN: 9780393244939
Publisher: W. W. Norton & Company
Published: 2014-01-10T00:00:00+00:00

There have to be common denominators to a common chemical sense. Humans and dogs, bees and butterflies: all are repelled by the fumes of ammonia, and all are attracted to the smell of alcohol. They all dislike the bitter taste of quinine, and they all like the sweet flavour of sugar.

We all seem to have a unique body odour, but no one seriously suggests that each of the six billion humans now alive has a different body chemistry and a different odorous substance. The secret is in the mix, and there is an astonishingly large number of permutations of a small number of basic ingredients. Even the most complex genetic programs are written with just four molecules, made up of only sixteen chemical elements. Nature is notoriously niggardly about raw materials, and yet endlessly and generously inventive with them.

Most organisms find food, avoid enemies and locate mates in much the same manner: with chemistry. Even in plants, a simple chemical sense controls movement and growth. Roots reach out towards growth-promoting substances, and exude other chemicals which percolate menacingly through the surrounding soil, inhibiting the growth of rivals so well that many desert species become so evenly spaced that they seem to have been planted by hand.

And yet there is an amazing bond between all living things, something that seems to allow a potted plant, as found in one classic experiment, to become aware of the death nearby of brine shrimp being dumped at random intervals into boiling water.203 Why should this be? Even if dying shrimp do indeed send out a distress signal, why should it be of any interest to a rubber plant?

Birds, bees and trees all have alarm signals. And some of them are interspecific. Terns, plovers and willets, feeding in the same area as a group of gulls, all take flight at the sound of the gull alarm call. Such signals have high survival value and work well across the species line, but not all species function on the same frequencies or even with the same sense organs. So there could well be a strong natural pressure towards the evolution of a common signal, a sort of all-species SOS, warning perhaps of a common danger such as the approach of a seismic wave or the imminence of an earthquake.

A signal accessible to all life would have to be very basic. Almost certainly it would be something chemical, a molecular messenger such as the volatile hydrocarbon that sends mites of many kinds scattering out of an area when it blows through like a fire alarm. Or the stable nitrogen compound which works for all ticks, and goes both ways, stimulating dispersal when humidity is high, and encouraging aggregations in drier weather.179 Returning to the question of individual odour, it seems that this may come about as a result of unique genetic influences on such simple substrates.

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