Since Darwin revealed his seminal theory of evolution by natural selection, human beings have endeavored to understand their own evolutionary origins and history. A lot of questions still remain, but these mainly pertain to the specifics. Today, paleoanthropologists understand in great detail the evolutionary emergence of a number of traits that we consider, at least superficially, unique to modern humans.
Human beings and chimpanzees, our closest living genetic relatives, are thought to share a common ancestor that lived 6 to 8 million years ago. This is based on genetic differences, where anthropologists have compared rates of mutation in both species and estimated how long this might have taken to result in the genetic differences we see today, resembling something of a genetic clock.
Since then, multiple branches in the tree of human evolution have come and gone, while some had descendants who evolved into species that eventually became modern humans.
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