A human being, or modern human (Homo sapiens), is the most common and widespread species of primate. Humans are characterized by their hairlessness, bipedalism, and high intelligence, with large brains that enable advanced cognitive skills, the ability to thrive and adapt in varied environments, develop complex tools, and form intricate social structures and civilizations. Anatomically, humans are similar and related to the great apes, such as orangutans, chimpanzees, bonobos, and gorillas, but are distinguished by a more highly developed brain that allows for articulate speech and abstract reasoning, as well as a marked erectness of body carriage that frees the hands for manipulative use. The term "human being" refers to a person, especially as distinguished from other animals or as representing the human species.