Chemical Signaling

Satellite disk One of the most fascinating studies being done in science these days involves the methods by which animals communicate and find food. All of us have seen dogs, cats, and numerous wild animals sniffing trees, piles of grass, and even rocks. We have also seen animals rolling in certain areas of the ground, rubbing on trees or posts, and urinating much more frequently than would be necessary just to relieve their bladders. Just walking your dog, you will see behavior like this on a regular basis. As the genomes of animals are studied and the genes identified that do certain things, it becomes obvious that some very careful planning has gone into providing animals with the means of finding food, mates, and avoiding conflict.

Most mammals have at least 1,000 genes that are responsible for the development of just their olfactory systems (those that allow the animal to obtain and identify odors). Humans have around 300. What that means is that we humans are limited as to what we can smell and how well we can identify and use our sense of smell. Many mammals can pick out and identify as many as 500,000 different odors.

Dog sniffing at a fire hydrant One thing this does is to allow the animals to tell who of their species has been in the area. its age, sex, and even the status of its health. This helps animals avoid conflict , find water, and cooperate in some ventures where a combined effort is needed. Another thing it does is help animals find food. A snake can follow a dying animal across the ground by odors alone. Finding fruits, grasses, and even roots can be done by the odor they emit, and those odors can be detected in many cases over a distance of miles.

Human nose Humans have other means of communication and the securing of food so these senses are much less developed, and little brain space is used to process odor information. For an animal with a brain, the size of a small nut to have the ability to use and process 500,000 different odors is incredible, but it works because of its design and integration into its lifestyle. This design speaks basically of the wisdom and planning of a designer that has provided for myriads of life forms to exist in a complex and changing environment.

--Reference: "Making Sense of Smells," National Wildlife, October/November, 2001.

--John N. Clayton

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