Humans have a highly developed brain, capable of abstract reasoning, language,introspection, and problem solving. This mental capability, combined with an erect body carriage that frees the hands for manipulating objects, has allowed humans to make fargreater use of tools than any other species. Mitochondrial DNA and fossil evidence indicates that modern humans originated in Africa about 200,000 years ago. With individualswidespread in every continent except Antarctica, humans are a cosmopolitan species. As of August 2010, the population of humans was estimated to be about 6.8 billion.
Likemost higher primates, humans are social animals. However, humans are uniquely adept at utilizing systems of communication for self-expression, the exchange of ideas, andorganization. Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans haveestablished an extremely wide variety of values, social norms, and rituals, which together form the basis of human society.
Humans are noted for their desire to understand and influencetheir environment, seeking to explain and manipulate natural phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the developmentof advanced tools and skills, which are passed down culturally; humans are the only animal species known to build fires, cook their food, clothe themselves, and use numerous othe