Pheromones are chemicals emitted into the environment by one organism, that affect the physiology or behavior of another organism of the same species. Human pheromones are chemicals that are uniquely human or unique in being encountered by humans. That is to say, a subset of the human chemicals may also be used by other species, like mice and rats, dogs or cats. Mice and rats can tolerate humans, since we have a few common chemical components in our pheromone sets. We tolerate, even celebrate dogs and cats for the same reason. Those wagging tails are pheromone emission devices bent on chemical addiction and canine parasitism. Indeed, lay reports of healthy, un-stung neonates being found covered with ants arise from the presence of shared nursing pheromone with the ants in the vernix caseosa--the slippery goo of delivery. The ants were merely trying to take care of the baby as they would one of their own. Human pheromones are often large sets of various chemicals produced by human skin or they can be made by the microflora on top of the skin using pre-pheromones coming out of the skin's various glands. Skin glands include appocrine, eccrine, and sebaceous and humans have more scent glands than any other animal. So why, at last count, do we have thirty-six types of sebaceous gland? Why do they grow up and die back? Why do they emit during human emotional behavior? Human pheromone amount and composition varies by anatomical location because pheromone transmission behaviors vary by social context. Since the brain controls emissions either directly or indirectly through skin heating, different signals pertain to different social needs. Humans kiss different people differently at different times of the day or night, in different seasons (slightly), and at different stages of life, of relationships. Kisses can be targeted quite specifically, and it is often a shock to find out that the niceness of kissing subserves the chemical ecology of chemical transmission and communication. The microflora of the human skin differs from those of other animals. It is interesting to note that isolated groups often share microflora as well as a group scent. Presumably, all the little tribes of microbes of human skin are transmitted among group members by social behavior: shaking hands, back slapping, kissing, hugging, touchdown celebrations, etc. (Finally, a biological reason for football.) Pheromones are species specific, mostly; they are also extremely synergistic in that single components always have less effect than correct concentrations of multiple emissions. Pheromones are also potent. Indeed, pheromones in correct proportions are the most potent drugs ever discovered or fabricated, being effective at the ultra-trace level (ppb). Pheromones are stereospecific, in that enantiomers often have different or even poisonous effect. For instance, humans have only cis (c shaped) fatty acids in their pheromones and we all vaguely comprehend the error in eating large dietary quantities of trans fatty acids. For generations, scientists, more learned than wise, have investigated the beneficial health effects of various snake oils, fish oils, and wildflower oils. Absurdly romantic notions of an assumed wide variety in the diet of hunter-gatherers (contrary both to fact and reason) led writers to explain the evolution of human health benefits of deep sea fish oils. Never mind that any common idiot knows that primitive humans deep sea fishing over wide geographic regions is an unlikely scenario. It is God's joke that the most healthy diversity of oils lies upon human skin, ripe for kissing. Perception of pheromones in animals is the province of microvillar or microciliary cells found within specialized pheromone perception organs and scattered about in the respiratory system in just the right places. Humans don't have tails to swish around to help them optimize territorial patrolling, so we haven't much use for Jacobsen's organ, also called the vomeronasal organ. Humans use crying for pheromone recognition at key times of life. Tears flow into the bottom of our triple-tiered pheromone reception centers right behind our faces and allow chromatographic separations up the hiatus semilunaris retorted by sinuses. It is interesting to note that the airflow through the two top passageways, meati, are always one way inward, just as seen in other animals--except in sneezes of course. It is noteworthy to observe that exhaled air is always extremely clean and provides clean space punctuation for chemorecognition, even in sobs. The lachrymal fluid contains dissolved receptor proteins that use the unusual salts in tears to signal presence of various pheromones detected by micro-ciliary pheromone sensing cells that line well-chosen places of the human upper respiratory tract. Pheromone hits dissolved pheromone receptor protein, the protein snaps open to release the salts, creating a potential difference (voltage) sensed by the microciliary cell which passes the information onto the brain. The more general sense of smell works similarly, even using temperature changes to parse scent components--the reason for sniffing. Every human emotion, from fear to hate, love, panic, embarrassment, even modesty functions in social chemorecognition. Thus the warmth of affection produces different emission sets from cold fear. See? We are at least vaguely familiar with the highly choreographed physiology and chemical ecology that decimate our populations, regulating our fertility as a group, all for the benefit of our genes and the needs of the hunter-gatherer clan. It's just that pheromones are generally imperceptible, at least consciously. Brain scans have noted our brains going crazy when we are presented with human pheromones that have no odor, no color, and almost no mass at all. And it is not surprising that the bright spots regulate emotion, violent behavior, obsessive behavior, autoimmune function, even the electrodeposition of atherosclerotic plaques! So what can we glean from all this? Medicine needs to quit ignoring exocrinology and chemical ecologists need to attend medical school. That may not happen for generations. That is too bad. Meanwhile, a few people can benefit from pheromones, as even at this primitive stage of our learning we have elucidated some benefits. Some human pheromones cause jealousy; another set causes lust, another warm feelings, another congeniality, another, hostility. One set, carefully collected, cures juvenile delinquency, which turned out to be a pheromone deficiency. Crime is natural human behavior, evolved to cull the herd about the time mankind outsmarted predators and started doctoring. It makes sense that it would have a chemical signal turning it off where it was inappropriate. And our recent epidemic, including Jihad, can be attributed to mistaken changes in hygiene and to the irritating effects of ozone and air pollution. Why are spouse abuse reports peaking with the first summer heat? Why are few crimes committed in high winds? Why is ozone concentration correlated with criminal activity? Now we may have the answer.