Ask A Scientist© Biology Archive

Author:      jmagee
Text:        How long has man as a species existed on the planet?

Response #:  1 of 1
Author:      wizkid
Text:        Human evolution is a matter of considerable debate.  Since the 
phrase in the question, "man as a species," is a bit vague, here is a brief 
run-down of the fossil evidence for the evolution of hominids (animals able to 
walk upright):
  Australopithecus - the first hominid, appeared on the African savannas 2-3 
million years ago.  Brain size was 1/3 modern human's.
  Homo habilis - the first hominid to make and use tools.
  Homo erectus - a. k. a. Peking and Java man, evolved from Homo habilis about 
1.5 million years ago, built fires, resided in huts, and had a brain capacity 
of 1,000 ml (versus modern man's 1,375 ml).
  Homo sapiens -
    1.  Neanderthals:  130,000 - 30,000 yrs ago,
    2.  Cro-Magnon Man:  90,000 yrs ago

The oldest fossils of Homo sapiens are those of the Neanderthals (130,000 - 
30,000 yrs ago), found in the Neander Valley of Germany.  Compared to modern 
humans, they had heavier brow ridges, less pronounced chins, and slightly 
larger brains.  Plus, they were adept in making and using tools and even had 
burial rituals.  They eventually became extinct and probably did not 
contribute to the modern human gene pool.  The oldest fully modern fossils are 
those of Cro-Magnon man, dating back 90,000 years.  Interestingly, Cro-Magnon 
and Neanderthal Men may have coexisted, but only Cro-Magnon Man contributed to 
the modern gene pool.