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Smell of death

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23.10.2007

Odorant chemical agents, pheromones, serve for animals’ contact purposes. Animals mark the territory by odorous discharges, demonstrate their hierarchic roles or sex attribute to their congeners, regulate propagation in the group, provide for the mother/baby interrelation.

Pheromones perform a lot of functions, and the researchers are striving to perceive them all, but they carry out the investigations mainly on healthy animals. Chemical signals of sick animals have been much less studied although they are no less interesting.

B.P. Surinov worked with the mice, part of which had received a fatal dose of gamma irradiation, and part – a toxic dose of lead nitrate, and one more group of animals was inoculated with cancerous growth. The animalsurine was collected on a sheet of filter paper, which was placed under the netted bottom of the cage for twenty-four hours. Then it was the turn of healthy tester- mice. They were placed one at a time into a cage, where paper with urine samples of experimental and healthy animals was lying in secluded nooks. The tester-mouse would follow the smell and the experimentalist observed which paper it would choose.

It has turned out that at the early stage of irradiation, poisoning or tumour development, pheromones of sick mice attract their congeners. The same action is produced by the urine smell of the rodents that are not threatened with death, for example, of the ones that had experienced stress or received a non-fatal radiation dose. When the pathology has developed and the mouse’s fate has been determined, its urine acquires repulsive properties, which are particularly noticeable on the eve of the death. The smell action does not depend on the pathology nature, but it only depends on its severity. The meaning of repulsive signals is clear: they limit contacts of seriously ill animals and prevent possible spread of infection (apparently, the pheromone notifies only about severity of the sick animal’s state, but does not inform about the exact diagnosis). The researchers are still to sort out the reason why the pheromones attracting to a sick animal are needed.

Chemical signals about pathology are typical not only of animals, but also of people. Back at the times when the main role in medicine was played not by devices and analysis, but by the doctor’s experience and intuition, physicians noted that the patients with different diseases have specific smells, and physicians even diagnosed by the smell of urine. And several days before the death, a specific smell appears with severely ill patients, the specialists calling the smell the harbinger of death.

Consequently, animals (probably likewise human beings) have the olfactory signal mechanism to inform about the critical state of the organism. It regulates animals’ behavior.

Nadezda Markina | Source: alphagalileo
Further information: www.informnauka.ru

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