Comparisons, olfactory system (Gross, Low)

Structure List Dog olfactory tract Human olfactory tract

Lower vertebrates and many mammals rely heavily on the sense of smell for information about the environment. These animals are said to be macrosmatic. In Class Mammalia, the dog is a familiar example. Humans are microsmatic, with smell being much less important than the other senses, especially sight and hearing. The study of comparative anatomy contributes much to the understanding of those parts of the brain directly involved in olfaction, which constitute the rhinencephalon. Olfaction is the only one of the five senses that leads directly to the cerebrum without modulation (thalamic). Can you think of any reasons for this difference?