Human evolution and computerized dating
The social brain hypothesis was proposed by British anthropologist Robin Dunbar, who argues that human intelligence did not evolve primarily as a means to solve ecological problems, but rather as a means of surviving and reproducing in large and complex social groups.
Some of the behaviors associated with living in large groups include reciprocal altruism, deception and coalition formation.
One consequence of this was that the north African tropical forest began to retreat, being replaced first by open grasslands and eventually by desert (the modern Sahara).
As their environment changed from continuous forest to patches of forest separated by expanses of grassland, some primates adapted to a partly or fully ground-dwelling life.
This reduced the human population to less than 10,000 breeding pairs in equatorial Africa, from which all modern humans are descended.
These environmental pressures caused selection to favor bipedalism: walking on hind legs.They spread throughout Africa over the following approximately 50,000 years.According to proponents of the Toba catastrophe theory, the climate in non-tropical regions of the earth experienced a sudden freezing about 70,000 years ago, because of a huge explosion of the Toba volcano that filled the atmosphere with volcanic ash for several years.Many traits of human intelligence, such as empathy, theory of mind, mourning, ritual, and the use of symbols and tools, are apparent in great apes although in less sophisticated forms than found in humans, such as great ape language.The great apes (hominidae) show considerable cognitive and empathic abilities.