Scientific America MIND has a special sex edition right now. And the deep dive it does on pheromones is just splendid.
Basically for much of history, anatomists had completely missed a full set of nerves that lead, along with other nerves from the brain (~~!nasty warning!~~ apparently they missed them because when you pull the brain out of the skull, these delicate nerves are usually severed with the tough membranes surrounding the brain, like I said, nasty warning, sorry). Anyways, these nerves run very close to the olfactory nerves but they aren’t for smell. They’re highly suspected to be for pheromones (that’s based on a number of studies, particularly of whales, whose olfactory nerves were lost as they evolved to lose their sense of smell and have their ‘nose’ or blowhole on top of their head).
Cool fact 1 among many. You think your eyes are cool? They have 3 different types of cones that process red, blue and green. That combo produces all the images you see right now. Sweet huh? Your nose 347 different receptors. Think how intensely sophistimicated that is! Also, smell is the most advanced sense of the animal world. Even bacterium determine food from toxin by way of smell. And let’s not even get into a dog’s sense of smell. Oh, snap.
Now for the sexy cool shit. If you have any doubt pheromones are involved in sex, consider the following example (this is one of hundreds scientists have observed). When a mouse gets knocked up, if she smells the urine of the male that did the dirty work, nothing happens. The embryo will implant itself and the lady mouse will have babies. Now, if, before the embryo implants itself, the lady mouse smells the urine of a different male (one with which the female mouse did not copulate), the embryo will NOT implant. Oh, snap.
Now for one of the cooler things as per the human side. The new nerve scientists have discovered runs very close along the olfactory nerves. The olfactory nerves go to a part of the brain that can be consciously recognized. However, the pheromone detecting nerve bypasses this part of the brain and goes to a part of the brain that we don’t consciously recognize. Put another way, the inputs from this nerve effect our brain on a completely unconscious level. This means that you have no idea that these pheromones are effecting you and your decisions in incredibly complex ways.
Reason with you mind, love with your nose. Love might truly be blind.