Plants create essential oils by mixing together dozens of fragrant molecules. The functions of these fragrant molecules is primarily to attract pollinators and repel herbivores (generally insects in both cases) and to guard against fungal or bacterial infection. Interestingly, bacteria often produce fragrant molecules too. Insects produce the same aromatic molecules, which they use for intra-species communication. In insects we call them pheromones, and they impart messages that relate to mating, scent trails to food, alarm signals etc.
Mammals don’t produce the same highly volatile fragrant molecules. […]