- The term “pheromone” Was coined by Peter Karlson and Martin Lüscher in 1959 based on the Greek words phero (“I carry” or “I bear”) and hormon (“stimulate” or “impetus”).
- While hormones are chemical messengers that act within the body, pheromones are excreted or secreted to elicit a response in other members within a species.
- In insects and larger animals, the molecules may be released in perspiration, genital secretions, or oils. Some of these compounds have discernible scents, while others are a form of odorless, silent communication.
The response to these chemical signals includes a wide array of behaviors. For example, the female silk moth releases the molecule bombykol that attracts male moths. Male mice release the molecule alpha-farnasene in urine that accelerates sexual development in female mice.
What About Human Pheromones?
If you’ve ever been attracted by a perfume or repelled by strong body odor, you know a person’s scent can elicit a behavioral response. Yet, are pheromones involved? Possibly. One problem lies in identifying specific molecules and their effect on behavior — a feat vastly complicated by the complex nature of human responses. Another issue is that the biomolecular machinery used in other mammals to detect most hormones, the vomeronasal organ, is all but vestigial in humans. Thus, a pheromone identified in a mouse or pig may also exist in humans, yet we may lack the chemoreceptors needed to react to it.
In other mammals, pheromones are detected by cells in the olfactory epithelium and vomeronasal organ. The human nose contains olfactory epithelial cells which transmit signals to the brain. Humans, apes, and birds lack a functioning vomeronasal organ (Jacobson’s organ). The organ actually is present in a human fetus, but it atrophies in adults. The families of receptors in the vomeronasal organ are G protein-coupled receptors that differ significantly from receptors in the nose, indicating they serve a different purpose.
Finding pheromones in humans is a three-part problem. Researchers have to isolate suspected molecules, identify a reaction due solely to those molecules, and figure out how the body detected its presence.
Possible Human Pheromones and Their Effects
Odors play a role in human sociosexual behavior, but they are hard to study because subjects need to be clean and odorless to discount effects caused by other scents. Three classes of possible human pheromones have been studied more than others:
Axillary steroids: Axillary steroids are released at puberty from the apocrine (sweat) glands, adrenal glands, testes, and ovaries. The molecules androstenol, androstenone, androstadienol, androsterone, and androstadienone are potential human pheromones. Most results on the effects of these steroids indicate they affect mood and increase awareness, rather than act as attractants. However, double-blind, placebo-controlled experiments by Cutler (1998) and McCoy and Pitino (2002) did show a correlation between steroid exposure and sexual attraction.
Vaginal aliphatic acids: Aliphatic acids in rhesus monkeys, collectively known as “copulins,” signal ovulation and readiness to mate. Human females also produce these compounds in response to ovulation. However, it’s unknown whether human males perceive them or whether the molecules serve an entirely different purpose.
Vomeronasal stimulators: Some adult humans maintain slight vomeronasal organ function, but it’s absent in most people. To date, no study has compared responses to vomeronasal stimulating compounds in the two different groups. Some studies indicate humans may have some vomeronasal receptors in the olfactory epithelium. However, other studies identify the receptors as inactive.
While not pheromones, per se, the major histocompatibility complex (MHC) markers on human cells are known to play a role in human mate selection. MHC markers are found in axillary odors.
In humans, as in other species, pheromones may affect nonsexual behaviors. For example, secretions from areolar glands of a lactacting woman’s nipples elicit a suckling response in infants, even those from another mother.
The bottom line is that humans most likely produce pheromones and react to them. There’s simply no concrete documentation identifying the role of such molecules or the mechanism by which they act. For every study showing a positive effect of a proposed pheromone, there is another study indicating the molecule has no effect at all.
You can buy body sprays and perfumes said to contain human pheromones. They may work, but the aphrodisiac is most likely the placebo effect, not any active ingredient. Basically, if you believe you are attractive, you become more attractive.
There are no peer-reviewed studies proving any pheromone product influences human behavior. The companies that produce such products regard their composition as proprietary. Some contain pheromones identified and obtained from other species (i.e. not-human pheromones). Others contain distillates obtained from human perspiration. The companies may say they have performed internal double-blind, placebo-controlled trials. The question you have to ask yourself is whether you trust a product that refuses peer review study to do what it promises. Also, it’s unknown what negative effects may accompany pheromone use.