Danismyname would like someone to explain why we don't see species forming before our eyes. The short answer is that it takes a long time. Just confining ourselves to the subject of the original posting which deals with the evolution of H. erectus from some Australopithecus species:
The article shows that change was fairly slow, seems it took a million years, from 2.5 to 1.5 million years ago. A single small group of apes did not wake up one morning and suddenly find themselves to be human. It's not like becoming a rock star.
I remember finding an article in Nature vol. 441, no. 7097, 17th May 2006, entitled "Genetic evidence for complex speciation of humans and chimpanzees". Unfortunately I cannot find the full article on the net again. However you should be able to find at least a summary somewhere if you type in the above information in your search engine. In it the authors suggest the earlier split between apes and humans took three and a half million years, from 7.5 million years ago to 4 million years ago. In other words all the time from Sahelanthropus to Australopithecus. The divergence involved several periods of back hybridising.
Lets concede for a moment that all humans have evolved from a single human, a couple or even a small group. How can we account for the regional variation of modern humans without falling back on some form of evolution? We know that nearly all species vary over their geographic range. Sometimes the extremes are classified as separate species. Do horses, donkeys and zebras for example come from a common ancestor? In spite of myths the hybrid between a male horse and a female donkey are not always sterile. It's just the hybrid is useless to us humans.
Hope that clears up your puzzlement
