1) The first research on pheromones was conducted in the 19th century and showed that female butterfly antennae detect male pheromones. 2) Further research provided evidence that human pheromones can synchronize women's menstrual cycles, as demonstrated in a famous study by Martha McClintock. 3) Additional studies showed that human pheromones come in two forms: primer pheromones cause long-term changes like hormonal changes, while releaser pheromones produce rapid short-term effects like sexual arousal.