Modern humans (Homo sapiens, primarily ssp. Homo sapiens sapiens) are the only extant members of the hominin clade (or human clade), a branch of the great apes; they are characterized by erect posture and bipedal locomotion, manual dexterity and increased tool use, and a general trend toward larger, more complex brains and societies.Early hominins—particularly the australopithecines, whose brains and anatomy are in many ways more similar to ancestral non-human apes—are less often referred to as ""human"" than hominins of the genus Homo. Some of the latter used fire, occupied much of Eurasia, and gave rise to anatomically modern Homo sapiens in Africa about 200,000 years ago. They began to exhibit evidence of behavioral modernity around 50,000 years ago, and migrated in successive waves to occupy all but the smallest, driest, and coldest lands. In the last 100 years, this has extended to permanently manned bases in Antarctica, offshore platforms, and to orbiting the Earth.The spread of humans and their large and increasing population has had a profound impact on large areas of the environment and millions of native species worldwide. Advantages that explain this evolutionary success include a relatively larger brain with a particularly well-developed neocortex, prefrontal cortex and temporal lobes, which enable high levels of abstract reasoning, language, problem solving, sociality, and culture through social learning. Humans use tools to a much higher degree than any other animal, are the only extant species known to build fires and cook their food, as well as the only extant species to clothe themselves and create and use numerous other technologies and arts.Humans are uniquely adept at utilizing systems of symbolic communication (such as language and art) for self-expression and the exchange of ideas, and for organizing themselves into purposeful groups. Humans create complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established an extremely wide variety of values, social norms, and rituals, which together form the basis of human society. Curiosity and the human desire to understand and influence the environment and to explain and manipulate phenomena (or events) has provided the foundation for developing science, philosophy, mythology, religion, anthropology, and numerous other fields of knowledge.Humans began to practice sedentary agriculture about 12,000 years ago, domesticating plants and animals, thus allowing for the growth of civilization. Humans subsequently established various forms of government, religion, and culture around the world, unifying people within a region and leading to the development of states and empires. The rapid advancement of scientific and medical understanding in the 19th and 20th centuries led to the development of fuel-driven technologies and improved health, causing the human population to rise exponentially. By 2014 the global human population was estimated to be around 7.2 billion.