Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon (P. lotor), is often known simply as 'the' raccoon, as the two other raccoon species in the genus are native only to the tropics and are considerably lesser-known. Genetic studies have shown that the closest relatives of the raccoon are the ring-tailed cats, coatis and cacomistles. Raccoons are unusual, for their thumbs (though not opposable) enable them to open many closed containers (such as garbage cans and doors). They are omnivores with a reputation for being clever and mischievous; their intelligence and dexterity equip them to survive in a wide range of environments and are one of the few medium-to-large-sized animals that have enlarged their range since human encroachment began (another is the coyote). Raccoon hindfeet are plantigrade similar to those of humans and bears.