A new study has found that silverback gorillas use odor as a form of communication to other gorillas

According to the results, the male silverback may use odor as a modifiable form of social communication, where context-specific chemical-signals may moderate the social behaviors of other gorillas. The authors predicted extreme silverback odor, where the odor was the only element that could be smelled in the surrounding air, by the presence and intensity of interactions between different gorilla groups such as silverback anger, distress and long-calling auditory rates, and the absence of close proximity between the silverback and the mother of the youngest infant. The authors suggest that odor communication between apes may be especially useful in Central African forests, where limited visibility may necessitate increased reliance on other senses.
Michelle Klailova added, "No study has yet investigated the presence and extent to which chemo–communication may moderate behaviour in non-human great apes. We provide crucial ancestral links to human chemo-signaling, bridge the gap between Old World monkey and human chemo-communication, and offer compelling evidence that olfactory communication in hominoids is much more important than traditionally thought."
Source-Eurekalert