Humans
Modern humans evolved from a lineage of upright-walking apes that has been traced back over 6 Ma to Sahelanthropus. The first known stone tools were made about 2.5 Ma, apparently by Australopithecus garhi, and were found near animal bones that bear scratches made by these tools. The earliest hominines had chimp-sized brains, but there has been a fourfold increase in the last 3 Ma; a statistical analysis suggests that hominine brain sizes depend almost completely on the date of the fossils, while the species to which they are assigned has only slight influence. There is a long-running debate about whether modern humans evolved all over the world simultaneously from existing advanced hominines or are descendants of a single small population in Africa, which then migrated all over the world less than 200,000 years ago and replaced previous hominine species. There is also debate about whether anatomically-modern humans had an intellectual, cultural and technological "Great Leap Forward" under 100,000 years ago and, if so, whether this was due to neurological changes that are not visible in fossils.
Read more about this topic: Evolutionary History Of Life
Famous quotes containing the word humans:
“Because humans are not alone in exhibiting such behavior—bees stockpile royal jelly, birds feather their nests, mice shred paper—it’s possible that a pregnant woman who scrubs her house from floor to ceiling [just before her baby is born] is responding to a biological imperative . . . . Of course there are those who believe that . . . the burst of energy that propels a pregnant woman to clean her house is a perfectly natural response to their mother’s impending visit.”
—Mary Arrigo (20th century)
“To not be afraid in our world is the message that doesn’t derive from reason, but maybe from this mysterious capacity given to humans which we call—not without a little embarrassment—faith.”
—Friedrich Dürrenmatt (1921–1990)
“The worst condition of humans is when they lose knowledge and control of themselves.”
—Michel de Montaigne (1533–1592)