How far removed are we from our proto-human ancestors? Not as much as one would think. Richard Wrangham has a creative way to illustrate that in the beginning of his book Catching Fire: How Cooking Made Us Human:
Although the australopithecines were far different from us, in the big scheme of things they lived not so long ago. Imagine going to a sporting event with sixty thousand seats around the stadium. You arrive early with your grandmother, and the two of you take the first seats. Next to your grandmother sits her grandmother, your great-great-grandmother. Next to her is your great-great-great-great-grandmother. The stadium fills with the ghosts of preceding grandmothers. An hour later the seat next to you is occupied by the last to sit down, the ancestor of you all. She nudges your elbow, and you turn to find a strange nonhuman face. Beneath a low forehead and big brow-ridge, bright dark eyes surmount a massive jaw. Her long, muscular arms and short legs intimate her gymnastic climbing ability. She is your ancestor and an australopithecine, hardly a companion your grandmother can be expected to enjoy. She grabs an overhead beam and swings away over the crowd to steal some peanuts from a vendor.
Evolution may happen at glacial pace from our perspective. But if you zoom out a bit, it happens incredibly fast. Interesting stuff.