However, the finding that the amount of volatile acids in vaginal washings from rhesus monkeys increased after incubation at 37°C, but was inhibited by autoclaving or the addition of penicillin before incubation, indicates that pheromonal production depends on bacterial action within the vagina. Gonadal hormones might regulate acid production in vivo by determining the availability of the substrate or the pH of the vagina (Bonsall and Michael 1971; Michael et al. 1972).

19.4. The role of pheromone signals in some other areas of behavior

In the previous pages, we have discussed information transmitted by chemical signals on species and individual identity and on physiological and social conditions of an animal. These messages are probably produced by many more primate species than have been studied so far and are likely to play important roles in a variety of behavioral contexts. They might function in orientation within the home range, and in the correlation of intergroup and intragroup social interactions, including consort relationships, spacing, aggression, territorial defense, and parent—infant relations. The lack of space does not permit me to review the evidence for all of these possible functions. Therefore, further discussion will be limited to a few behavioral categories where the importance of chemical signals is particularly intriguing. Learn about pheromones and sexual relationships.

19.4.1. Orientation by pheromone trail marking

Bolwig ‘(1960), Sauer and Sauer (1963) and Seitz (1969) have suggested that one of the functions of urine marking in prosimians, especially nocturnal species, is the production of odoriferous trails which help the animal to orient itself within its home range. Seitz (1969) showed that Nycticebus coucang is capable of using trails of its own urine to orient itself in a totally dark test room. When he introduced subjects into a totally dark room which did not contain any urine trails, the animal showed a phase of initial orientation during which they investigated their environment, continuously sniffing and urine marking.

Following the phase of initial orientation, the subjects showed less olfactory investigation and urine marking, and demonstrated that they were familiar with the new environment. When the subjects were tested under identical conditions after the investigator had applied trails of the subjects’ own urine to the floor of the test room, initial orientation in a new environment took place along the artificial urine trails. After surgical blinding, a female tested in a new environment increased the time she spent sniffing the new environment to 91.6% of the total test time as compared to only 21.1% when her eyesight was intact and she was tested in an illuminated test room. Although Seitz (1969) did not eliminate the possibility that his subjects used other senses (e.g. touch or hearing) during orientation in the test environment, his experiments strongly indicate that when eyesight is eliminated, olfaction can take over and urine trails help the animal to orient itself in an unfamiliar space. Check out pheromones at http://infospeak.org/?p=141.

The question remains, how strongly the animals rely on their own urine marks for orientation in a natural environment, where they” are hardly ever totally deprived of their ability to see. Seitz’s animals may well have learned to rely on their sense of olfaction and to use urine marks in orienting within a limited space which, after repeated testing, was not altogether unfamiliar to them and which was relatively simple in its three dimensional structure.

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