Evolution did not just happen overnight. It was very gradual and in order for humans to become the way we are today, we had to go through phases which took countless generations. Some of the first steps towards modern humans can be found in the Sahelanthropus Tchasensis which dates back 6-7 million years. While they still had a small brain (unlike our realtively large brain), their faces were flat and they had large brow ridges and small teeth. Those are features that are not found in apes and indicate that evolution towards modern humans had begun. Next, the Orrorin Tugenensis which dates back 6-5.8 million years was a huge discovery. What was so special about this species was its bipedal legs. Much like the rest of evolution, habitually walking bipedally did not happen quickly. Many of our ancestors had long arms along with bipedal legs which indicates that they may have primarily still lived in trees, however they were also comfortable on the ground. Later dating back 5.8-4.4 million years ago is the Ardipithecus, or “Ardi” for short. This species too still contained primitive features such as large canines, small brain and a grasping big toe, however it had bipedal legs with its forearm magnum underneath its skull which indicates that it was habitually walking on two feet and the shape of some of Ardi’s teeth look like those of later hominins. All of these species show some primitive traits along with some modern traits which help us in modern biology by giving us an idea of what the evolutionary tree looks like and how humans were created.
I found the most interesting part of this lesson to be the last two videos on Ardipithecus Ramidus and Australopithecus Sediba. These discoveries helped us understand that while humans and apes came from a common ancestor, that ancestor was neither ape like nor human like. We have often assumed that the ancestor resembled an ape simply because we have very little fossil records to prove that it did not. Realistically, apes and chimps have also been evolving for just as long as humans so they too could be very different from the common ancestor that we originated from. However, these discoveries show us that our common ancestor was some kind of entirely different species. Ardipithecus Ramidus fell very close to the point in time where humans split from apes on the evolutionary tree, however his hands were not as strong as the hands of apes would be. This indicates that Ardi was not walking on his knuckles. This tells us that knuckle walking is something that developed on the ape side of the evolutionary tree after we split from them. Ardi also had a grasping big toe so while we was walking bipedally, it was still not exactly how we are walking today. Australopithecus Sediba was also an important discovery because he is a very close to whole skeleton of a 9-year-old boy. This is still a recent discovery which means we are still learning new things about this species. We do however know that his legs were long and strong so he could walk upright and run comfortably.