Terrestrial vertebrate pheromones

What is it about?

Chemicals send messages about sex, dominance and fear - but do not fit a pattern Humans communicate mainly by sound and sight, but otheranimals communicate mostly by smell, using odors from breath, scent glands, skin, urine, faeces and scent marks, to recognise individuals, mark territory, assert dominance, warn others about danger, stimulate or retard development, attract mates, and share information about food sources. If we could harness the power of chemical signals, we could use them to control rodent pests, improve farm animal breeding, and keep large predators away from livestock, among other things. To use chemical signals as tools we have to identify the chemicals they contain, and so two chemical communication specialists and a statistician teamed up to look for patterns among the chemicals that animals use to communicate . Their search focused on terrestrial vertebrates; tortoises, lizards, snakes, birds and mammals. They asked whether different animals use similar chemical substances to communicate similar messages and whether ecological conditions, such as temperature and humidity, affect the chemical properties of the signals. Among the results of more than 200 published studies on terrestrial vertebrate chemical signalling, the researchers found no large scale patterns that relate chemistry to chemical message. The signalling chemicals range from easily evaporated liquids to solid proteins, and different animals use different chemicals to send similar messages, or send different messages by similar chemicals. The researchers suggest that the lack of large scale patterns is due to chemical signalling’s complexity. Terrestrial vertebrates’ chemical senses have such a high sensitivity and wide range that they can detect any of the huge diversity of chemicals produced by the animals and the microbes that live in their scent glands, skins, guts, and urinogenital tracts. Therefore any combination of the chemicals can be used as a signal. When very diverse chemistry combines with vertebrates’ intricate social signalling the resulting complexity defies tidy classification. To really understand chemical communication we would need to compare the chemical signals of a broad range of species living in different habitats, but, so far, signal compounds have been identified from only 23 of the 23 000 species of terrestrial vertebrates. Most of this research has been carried out on laboratory mice. Patterns might emerge when researchers moves out of laboratories to study animals in their natural habitats, and identify more chemical messengers from more species.

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Why is it important?

If we could harness the power of chemical signals, we could use them to control rodent pests, improve farm animal breeding, and keep large predators away from livestock, among other things. To use chemical signals as tools we have to identify the chemicals they contain, and that would be easier if the chemistry fitted identifiable patterns.

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