Animals use a wide range of signals to communicate with one another. In addition to the auditory cues like barking and meowing that everyone thinks of when considering animal signals, we know that they also utilise chemical, visual, and tactile signals. Using these varied signalling systems or combinations of them, some species have developed highly advanced methods of transferring information to one another. One great example of this was discovered in honeybees by animal behaviourist Karl von Frisch. Dr von Frisch was the first to interpret the round and waggle dances that foraging honeybees perform when they return to the hive. From his research, he found that these were a form of signalling for the bees. Using dances, the bees could communicate the distance and locations of sources of high quality pollen. He also noted that by performing the dance in close contact, the bees could also signal the type of food through their scents.↵
Signalling, however, is not used only for food gathering. Many animals use various means to signal their ownership of a territory and its boundaries. Perhaps the most common is scent marking. In this system, animals mark their territories by rubbing on items or urinating and defecating within their territories to warn other animals. This can also lead to a visual signal to other animals. Brown bears, for instance, rub their scent into trees and often leave behind tufts of hair in the bark. These clumps of hair can signal that the bear was there even after the scent has dissipated.↵
The great amount of information that animals can communicate using signals raises another important question: Does signalling constitute a language? Noted 19th-century naturalist Charles Darwin conducted basic research into this topic for his book Descent of Man (1871). In it, Darwin discussed similarities between animals' auditory signals and human communication. Although he ultimately felt that language distinguished humans from lesser animals, he could not help but notice that baby birds are taught to signal by their parents and that some gibbons utilise musical sounds for courtship and competition with rivals, much like humans.