FlexThis wrote:
I like the way you split the apes from the humans by a common ancester. Unfortuanately we have no proof of this common ancestor, no proof that humans could ever swing from tree to tree.
Well, its an important point. Most people believe that biologists suggest that we evolved directly from chimps, but this is not what evolution teaches. The theory of human evolution believes that we evolved from a series of ancestral forms. Modern animals are all descendants of some ancestral forms, and those ancestors are, in almost every case, long since extinct. Modern animals and humans all came from something previous that is long since gone. At some time in the distant past, wolves and lions shared a common ancestor. Populations of this common ancestor would have become isolated from one another geographically or behaviorally (animals that take on nocturnal habits could be said to become isolated form animals of the same species in the same location who are diurnal [the opposite of nocturnal], and the nocturnal animals will tend not to breed with the diurnal animals, and so differing mutations that gradually build up in each population of the same species can eventually build up differently in the two populations, and since the two populations are not exchanging these new genes by breeding with one-another, the eventual result is two different species from the original one, no longer capable of interbreeding even if they were operating on the same schedule), and genetic changes that build up in the two isolated populations of the same animals are not traded between them. The differing environmental pressures of the isolated areas (different temperatures, terrain, and available food) will cause these two isolated groups of the same species to gradually adapt differently to their different habitats, and eventually these two isolated populations of this one species will branch into two different species with different characteristics developed to fit their different habitats and you wind up with the ancestors of dogs and cats from a common ancestor.
The point is, cats and dogs share a common ancestor, and it is important to understand that that is not the same as saying that cats evolved FROM dogs, or vice-versa. Similarly, humans and chimps both evolved from a common ancestor, which is not the same as saying that humans evolved FROM chimps.
Damon, fossil evidence has been found of a variety of human ancestors. You are correct, the common ancestor of humans and other Apes is not known and described yet. However, this common ancestor of our and the other Apes is believed to have existed about six million years ago. Finding fossil evidence of human ancestors as old as three million years is rare and difficult to do, but over the past 100 years, since the search for the fossil evidence of human ancestors really took off with the discovery of the Neanderthals (dating from about 100,000 years ago to as recent as about 30,000 years in Europe and the Middle East) anthropologists have gradually uncovered, bit by bit, a relatively consistent fossilized trail of evidence of human ancestors going back a little beyond 3 million years (before we made stone tools, before we had brains any bigger than chimps, but not necessarily before we began to start walking upright). The majority of that older evidence is all from east and south Africa. Recently fossils were discovered in central Africa that date from around 4.5 million years old. The majority of existant chimps and gorillas live in west Africa. The point is, we haven't found all the fossil evidence that there is to find yet, not by far. We haven't even begun to look everywhere that there is to look. Unfortunately, bones simply don't fossilize the same everywhere; some environmental conditions favor fossilization, and some don't. In many cases we will not find fossils of human ancestors in places where our ancestors lived because bones were simply not preserved due to acidic soils or greater erosion or other problems. Not all the evidence that we could wish for even exists today. But there is still more evidence to be found, and it will gradually build up to demonstrate a very clear picture of the human evolution from earlier primate ancestors.
