What is known about human evolution from between 6 to 4 million years before present?

Question

What is known about human evolution from between 6 to 4 million years before present?

Answer 1

WHO KNOWS???? The earth is not that old.

Answer 2

Honestly, not that much. There are three hominin genera found before the first Australopithecine we know (A. anamensis 4.1 mya): Sahelanthropus, Orrorin, and Ardipithecus. We believe that they are human ancestors due to their rudimentary morphological adaptations to bipedalism (foramen magnum placement, tibia angles, femoral neck size) and their dentition (some species have thick enamel which is not present in other great apes).

Answer 3

If your talking Apes, what has that got to do with human evolution. There are some big names in Anthropology do believe that Man has walked the earth for tens of millions of years.

Answer 4

I liked lightnings response.  I would add that bipedalism probably evolved in Ororin more than 5 million years ago.  This tends to suggest that our common ancestor with chimps was a biped.  This doesn't set to well with anthropologists who assume that we are superior and therefore must have evovled from a knucklewalker.  There is very little evidence that we ever had a knucklewalker in our ancestry.  Human children never knucklewalk, but juvenile chimps do tend to walk bipedally.  Very little is known about this period.  Every fossil that is found is generally claimed to be a human ancestor because that makes it more valuable.  The truth is that they really don't know.  There is far more they don't know that they know.

Answer 5

What is fascinating is that our knowledge of human evolution changes with each new discovery.  The model I learned back in the early 1980's when I was an Anthropology student, including the human "family tree", is different than it is today.

Based on the most recent information:

Comparisons of DNA show that our closest living relatives are the ape species of Africa, and most studies by geneticists show that chimpanzees and humans are more closely related to each other than either is to gorillas. However, it must be stressed that humans did not evolve from living chimpanzees. Rather, our species and chimpanzees are both the descendants of a common ancestor that was distinct from other African apes. This common ancestor is thought to have existed in the Pliocene between 5 and 8 million years ago, based on the estimated rates of genetic change. Both of our species have since undergone 5 to 8 million years of evolution after this split of the two lineages. Using the fossil record, scientists attempt to reconstruct the evolution from this common ancestor through the series of early human species to today's modern human species.

Our understanding of the fossil record shows that distinctively human traits appeared neither recently nor all at once. Rather, they evolved piecemeal over a period of roughly 5 million years. By 4 million years ago, humans were habitually bipedal (walking on two legs) yet had brains roughly a third of the size of a modern human's (about the size of a modern ape's brain).  For more information see

http://anthropology.si.edu/humanorigins/...

For the Smithsonian Institute's "Human Family Tree" see

http://anthropology.si.edu/humanorigins/...

Answer 6

Virtually nothing is known.  It is highly likely that our common ancestor with a chimp occurred during that time but it is possible that it was sooner.  There are fossils during that time that have characteristics that indicate they were upright and possibly bipedal 6 million years ago.  It doesn't mean they were our ancestors.  The same thing goes for the bipedal fossils that were 4 million years old.  The current evidence points to them being most likely ancestors.  There just aren't even close to enough fossils to be sure.