The sense of smell is one of the earliest developed senses in existence, as well as one of the most important. Out of the subphylum Vertebrata, the class Mammalia have the greatest olfactory perception and the most specialized of noses. As well as in some other vertebrates, the sense of smell is distinct in mammals, but at the same time unlimited in its ability to tell the difference between smells.
The first people to notice the importance of scent glands in mammals were perfumers. These various glands produced the odours of musk, civet, castor, and ambergris. Musk is taken from the glands of the deer, civet from the anal glands of the civet, castor from the castor gland of the beaver and ambergris from the intestines of the sperm whale (Macdonald and Brown 1985).
Although the olfactory lobes are not as large as in many lower vertebrates, in general, olfactory organs and structure are well developed in mammals. The level of development correlates with the animal’s habits. This means, animals that rely the most on olfaction in their behaviour have greater sense capabilities. For most nocturnal mammals, having a keen sense of smell offsets their limited visibility in darkness. For most mammals, having a keen sense of smell aids in a nocturnal lifestyle. A class of Mammalia with a small portion of the brain dedicated to olfaction are the Primates. Their comparably poor sense of smell can be related to their daytime oriented lifestyle. Another lifestyle that can be taken into consideration is the aquatic existence. Whales for example, have either a reduced or completely olfactory sense due to their environment (Pough 2009). Stemming from this idea of development and lifestyles, the uses of olfaction in mammals are many.
One of these uses, which includes many different behaviours, is social functioning. Odors can be used to convey messages within a population and these messages can be conditioned from experience (Jameson 1921). When encountering strangers of the same species, there are 3 basic patterns of olfactory investigation. These naso-anal, naso-genital, and naso-nasal contact points are where investigation most often occur (Macdonald and Brown 1985). For example, when prairie dogs are fighting or irritated, their anal scent glands emit a strong musky odor which other prairie dogs can smell. Alternation of naso-anal smelling between male prairie dogs most often happens during disputes over territory (Cockrum 1962). Other gland regions can be investigated of course and this in seen in the red kangaroo. Males will lick or bite the patches of tubular glands on the chest or abdomen of other males. This happens when being threatened by another male (Dietland 1983).
A way for mammals to claim their territory without confrontation is by leaving scent marks. This behaviour is seen in nearly all male mammals in the form of urine, feces, by products from special gland regions left along the edges of the territory, or simply parts of the body that have...