Final answer:
Pheromones in animals are used for communication and behavior modification within a species; however, their role in humans is less clear and still being researched, with some evidence suggesting they can affect behaviors like menstrual synchrony.
Step-by-step explanation:
Pheromones serve various roles in animal communication, often being used by species for a range of behaviors, including mate attraction, alarm signaling, and trail marking for food sources. In humans, the role of pheromones is much more contentious. Although humans do produce substances like axillary steroids, which seem to affect human perception and certain behaviors like menstrual cycle synchronization, the extent and significance of pheromonal communication in humans compared to animals remain an active area of research. In terms of perception, pheromonal signals are usually sent to neural structures separate from those of standard odors, which project directly to the brain's emotional and reproductive centers, such as the amygdala and the hypothalamus. This distinction highlights the different way pheromones function as compared to other odorants.