According to recent studies, the human nose is capable to sense a wide range of smells, that cannot place them into any known category, but is still reacting to them. Such as the scent produced by a chemical called putrescine. This is a chemical that the body produces when it starts to decay, and one little thing to know, the scent is the result of the animal’s necrophobic behavior throughout the years of evolution, and these responses are thought to have evolved at least 420 million years ago.
The animals are thought that they react to the smell of putrescine as a sense of danger in a two different ways: the reaction that a predator is nearby, and the second is that they have been put in a life danger, so their instinct tells them to escape.
Scientists have made four different experiments on humans with a mixture of putrescine, water and ammonia, just to prove that human’s reactions and behavior are not any different than those of the animals.
Vigilance
The first experiment, where participants were tested to the scent of putrescine, as they were exposed to the scent of it and tested out their vigilance. The results showed that the participants who were exposed to the scent of putrescine showed more vigilance than those who were exposed to ammonia and water.
Escape behavior
The researches did the second test where they have tested unsuspecting group of people, who were given a task to rate a smell on it’s intensity, repugnance and familiarity. The researches wanted to see the group’s reaction to the smells, and how fast the participants would walk away at an 80m distance. Those who have smelled the putrescine, tended to walk away more quickly from the place, which proved that the smell evoked a strong motive to escape.
Escape-and-threat-related cognition
In another experiment, after the group being exposed to the scent of putrescine, the researchers gave the participants a word stem-completion task.
The results have shown that the smell of putrescine caused the group to complete the word stems, all realted with escape and other associations with the word escape. The smell also increased to use of thread words.
Defensiveness and hostility
The last experiment the participants were exposed to a very decent scent that they couldn’t detect. In this experiment, they were given a text to read, and the task was to evaluate the author of it.