Pheromones are among the great controversies of the scientific world. There are those that believe whole-heartedly that humans excrete pheromones as animals and insects do. The opposition agrees that human pheromones exist but disagree with the effectiveness of them on other human beings as they do in the animal kingdom and insect world. The debate has went on for many years with studies being conducted by numerous doctors and psychologists studying pheromones in their own tests with different controls and results being documented.

Pheromones are substances that occur naturally in one's body and are excreted externally that can convey messages by air that can elicit a response from others. The messages can elicit different responses in people depending on whether or not they are male or female. There are four different classes of pheromones that have been marked after years of study: territorial markers, mother-infant markers, menstrual synchrony and sex-attractant pheromones. There have been a lot of studies between the effects of a group of women living in the same environment, such as roommates that shows that their menstrual cycles will begin to occur about the same time; whereas before they started to live together their cycles were at very different times.

Humans are not as susceptible to pheromones as animals and insects are, however. It is harder to manipulate humans than rats or insects and keep them in a controlled environment. Humans also do not enact in the stereotypical behaviors one would expect after being exposed to certain pheromones as animals or insects would either. This could be because humans utilize all of their senses at once and are constantly aware of what is going on around them, rather than solely dependent upon pheromones for mating and finding food as insects would. The different pheromones can elicit different reactions depending on where the smell comes from and what sex the recipient is, such as an urge to mate, submission or aggression.

The vomeronasal organs are located within the nasal passage and are responsible for picking up pheromone signals from others. It is believed that the vomeronasal organs of humans have become dulled over time because we have lost the need to reproduce and produce offspring for the continuation of our species ? which is the main pheromone that animals and insects excrete. Because of this and the heightened awareness of our other senses we are just not as susceptible to chemical triggers as one would believe, although it is still a huge gimmick for marketing sex related products.

Pheromones exist but there is a huge debate in whether or not we are as susceptible to them as animals and insects are. There have been many studies conducted over the years to resolve the debate and have only succeeded in increasing the number of questions that the researchers have. Some people are more susceptible to the chemical excretions of others and make for good test subjects, but overall many people are not providing responses to the researchers as they had expected after studying the responses of insects and animals.