After comparing the proportion of the brain devoted to smell in different animals, Pierre Paul Broca suggested that mammals can be classed into two broad groups: macrosmatic mammals, such as dogs, have a finely tuned sense of smell which they rely on to perceive the world, while we, along with other primates and the marine mammals, are microsmatic—we have small olfactory organs that we only rely on to a small extent.
And although we may have fewer types of receptor than other mammals, Charles Greer at Yale University in the United States has shown that the human nose and brain are unusually well connected, with each group of receptors linking to many more neural regions than the case in other animals. That should give us a good ability to process incoming scent.
Rob Holland found that the hint of aroma wafting out of a hidden bucket of citrus-scented cleaner was enough to persuade students in a hostel to clean up after themselves.
William Overman and colleagues at the University of North Carolina in the United States found that when men were subjected to a novel smell—either good or bad—during a task used to test decision-making skills, they performed significantly worse than normal. The researchers conclude the scent stimulated brain areas connected with emotion, making their decisions emotional rather than rational.
Questions
1. A faint smell could motivate people to do household chores.
2. Humans are better equipped to interpret smell than other species are.
3. Smell is associated with feelings, rather than the logical part of the brain.
4. Humans do not require a sophisticated ability to smell.