In the beginning, some 4.4 Billion years ago shortly after water liquefied scientific consensus is that 'life' developed on our planet.
From then we have to wait quite the while for the appearance of our earliest ancestor - for the sake of argument we will begin with is the so called Millennium Man some 7 Million years ago. This is Orrorin Tugegenesis the first known human ancestor after divergence with out chimpanzee ancestors.
From their we move on to 'Lucy'. Lucy is an example of Australopithecus Afarensis and is a 3.2 Million Year Old partial fossil. From this we know that this species is perhaps a link with the Homo Species. A. Afarensis had smaller teeth than the great apes of the time and a noticeably different facial bone structure.
We have to move forward to 2.4 Million Years ago till we meet Homo Habilis which translates as Handy Man. Since H. Habilis was designated by some as an extinct species controversy has raged to whether it is our oldest 'homo' ancestor since some believe it closely resembles some Australopithicine species. Whats more is that with further studies and research some scientists now believe that H Erectus may predate our current estimates for its divergence. (Not to mention H Ergaster yet!)
Both H Habilis and H Eragster had far larger cranial capacities in comparison to the Australopithicines and used some rudimentary tools. It is thought H Habilis and H Erectus shared the earth at the same time.
H Erectus is also at the spotlight of debate - was it an ancestor or not? At the minute it is considered so. We know that Erectus was had a larger brain capacity as well as a shorter face and smaller jaw a shortening of the forearm and an exterior nose. In most ways H Erectus look very much like us. They are fossilised remains of H Erectus from 1.8 MYA to 1 Million Years Ago.
Moving to a mere 700,000 years ago we have Homo Heidelbergensis which is believed to look much like H Erectus although compared to Erectus's 74% Brain Capacity they had a 93% - when compared to Homo Sapiens. This species is also believed by some to be the common ancestor between Homo Sapiens and Homo Neanderthalensis. There are footprints caught in volcanic ash of this species in Italy.
Neanderthal Man has always held some sway over me, it may be to think that as little as 25,000 years ago they shared the earth with Homo Sapiens! Neanderthal Man is thought to have existed from around 350,000 years ago but its extinction is the subject of much debate. Did they just die off? Where they absorbed by breeding or was it like we see now and just displaced like so many other cultures?
The subject though of the most heated debate is when modern Homo Sapiens evolved. Many believe it was around 200,000 years ago. Even now debates rage regarding the Out of Africa hypothesis or multi regional belief. I do like the arrogance though, Homo Sapien - The Wiseman.
It is strange to think, is it not, about how little direct history we have - to think of our inexact records of Ancient Greece and compare that few thousand years to the unknown history of early man is quite mind boggling. I know that creationists shudder at the thought, I do too but in excitement - our current understanding is but a scratch on what their still is to find out and it is the honest and truthful journey that will bring the rewards of knowing.