and determining the presence of prey or predators in the local environment. Communication: Dogs and cats use licking both to clean and to show affection among themselves or to humans, typically licking their faces. Many animals use licking as a submissive or appeasement signal in dominance hierarchies. Thermoregulation: Some animals use licking to cool themselves. Cats do not sweat the way humans do and the saliva deposited by licking provides a similar means of evaporative cooling. Some animals spread saliva over areas of the body with little or no fur to maximise heat loss. For example, kangaroos lick their wrists and rats lick their testicles. Mating behavior: Post-copulatory genital grooming often occurs in male rats and prosimian primates. This behavior may prevent disease transmission. In primates Ring-tailed lemurs lick each other's babies as a means of collective grooming and of reinforcing social cohesion within the community. Macaques and other primates lick leaves for water in addition to dipping their arms into tree crevices and licking the water off. Chimpanzees use licking in a variety of ways: licking objects, such as dead trees, that others in their community have licked, licking each other's body parts for grooming and sex and licking rocks for salt. Gorillas use licking in addition to other senses to determine the nature of an object. In humans Compared to most other mammals, licking has a minor role for humans. The human tongue is relatively short and inflexible, and is not well adapted for either grooming or drinking. Instead, humans prefer to wash themselves using their hands and drink by sucking or pouring fluid into their mouth. Humans have much less hair over their skin than most other mammals, and much of that hair is in places which they cannot reach with their own mouth. The presence of sweat glands all over the human body makes licking as a cooling method unnecessary. Nonetheless, licking does play a role for humans. Even though humans cannot effectively drink water by licking, the human tongue is quite sufficient for licking more viscous fluids. Some foods are sold in a form intended to be consumed mainly by licking, e.g. ice cream cones and lollipops. Though useful, in some cultures it is considered improper table manners to clean one's fingers by licking during a meal. Some people in the Afar tribe of Ethiopia have been reported to have used their tongues to lick