A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species.
Pheromone chemicals are capable of acting like hormones outside the body of the secreting individual, that can affect the behavior of the receiving individuals.
They can be released by animals, insects, and humans, and they play a crucial role in various social behaviors such as attracting mates, marking territories, and signaling danger.
Chemical signals are typically detected by specialized receptors in the olfactory system, located in the nose.
Pheromones can elicit specific physiological or behavioral responses in the receiving individual.
Pheromones can vary in their composition and purpose, ranging from attracting potential mates to promoting aggregation or warning about potential threats.
In humans, the role of pheromones and their influence on behavior and attraction remain debated.
There are alarm pheromones, food trail pheromones, sex pheromones, and others that can affect behavior.
Trace amine associated receptors (TAAR) in the olfactory epithelium of animals can mediate attractive or aversive behavioral responses to a receptor agonist.
In humans, hTAAR5 presumably mediates aversion to trimethylamine, which is known to act as an hTAAR5 agonist and to possess a foul, fishy odor that is aversive to humans.
The Vomeronasal receptor in reptiles, amphibia and non-primate mammals detects pheromones by regular olfactory membranes, and also by the vomeronasal organ which lies at the base of the nasal septum between the nose and mouth and is the first stage of the accessory olfactory system.
The presence of a vomeronasal organ in the detection of pheromones is disputed.
A vomeronasal organ is clearly present in the fetus it appears to be atrophied, shrunk or completely absent in adults.
Olfactory processing of chemical signals like pheromones exists in all animal phyla and is oldest of the senses, generating behavioral responses to the signals of threat, sex and dominance status among members of the same species.
No pheromonal substance has ever been demonstrated to directly influence human behavior.
Three classes of possible human pheromones are: axillary steroids, vaginal aliphatic acids, and stimulators of the vomeronasal organ.
Human pheromones are chemical substances that can be released by the body and can have an effect on the behavior and physiology of other individuals.
Certain chemicals in our sweat, urine, and other bodily secretions may act as pheromones, but the extent and significance of human pheromones is debated.
Axillary steroids are produced by the testes, ovaries, apocrine glands, and adrenal glands, are chemicals that are not biologically active until puberty when sex steroids influence their activity.
The change in activity of axillary steroids during puberty suggests that humans may communicate through odors.
Several axillary steroids are possible human pheromones: androstadienol, androstadienone, androstenol, androstenone, and androsterone.
Androstenol is regarded as a female pheromone.
Androstenone is postulated to be secreted only by males as an attractant for women.
Androstenone is thought to be a positive effector for women’s mood.
Androstenone has different effects on women, depending on where a female is in her menstrual cycle, with the highest sensitivity to it during ovulation.
Androstadienone seems to affect the limbic system, and causes a positive reaction in women, improving mood.
Androstadienone negatively influences the perception of pain in women.
After androstadienone presentation, women tend to react positively while men react more negatively.
Data suggest that androstadienone may increase attention to emotional information causing the individual to feel more focused, modulating on how the mind attends and processes information.
These three molecules have yet to be rigorously proven to act as pheromones.
Pheromone receptor genes found in olfactory mucosa.
It has not been conclusively shown that humans have functional pheromones.
Experiments suggesting that certain pheromones have a positive effect on humans are countered by others indicating they have no effect.
No pheromonal substance has ever been demonstrated to directly influence human behavior in a peer reviewed study, and the role of pheromones in human behavior remains speculative and controversial.