Just because we are not consciously aware of the influence of chemical communication signals that inform and direct our behaviors does not mean they are not present in abundance. The same way chemical signals like hormones within the body inform and direct the behaviors of various cells and organs, chemical signals also do this between us. Pheromones are chemical signals that change the behaviors of other animals of the same species.
Pheromone actions in humans have been investigated, but the evidence thus far is generally considered weak. While the evidence of pheremonic communication among every other organism is staggering, signaling such things as alarm, where food sources are, triggering sexual arousal and behaviors, bonding behaviors, repulsion and attraction and so on, somehow we have resisted acknowledging this same communication channel happening among humans.
My guess is this area of science has been historically stagnated by false assumptions and wishful thinking. Perhaps a desire to keep humans in a special class, perhaps due to the fact that we idolize verbal awareness so much we confuse our meager, error prone , but convincing verbal map with the actual territory, but the evidence that we are just like every other biological organism, the product of a complex tapestry of communication on multiple levels, which we only get to see a fragment of, is now emerging with more convincing vigor. Here is one such study along those lines: