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:
“It is quite a common and vulgar thing among humans to understand, foresee, know and predict the troubles of others. But oh what a rare thing it is to predict, know, foresee and understand one’s own troubles.”
—François Rabelais (1494–1553)
“...there is hope for a tree, if it is cut down, that it will sprout again, and that its shoots will not cease. Though its root grows old in the earth, and its stump dies in the ground, yet at the scent of water it will bud and put forth branches like a young plant. But mortals die, and are laid low; humans expire, and where are they?”
—Bible: Hebrew, Job 14:7-10.
“Here we also see: what this divinity lacks is not only a sense of shame—and there are also other reasons for conjecturing that in several respects all of the gods could learn from us humans. We humans are—more humane.”
—Friedrich Nietzsche (1844–1900)