Week 5 – Early Fossils

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.

3 thoughts on “Week 5 – Early Fossils

  1. Archaeologists found a suspected new species of ape jaw fossil, which apes and gorillas, chimpanzees and the last common ancestor of humans is very close. The researchers said the fossil fill some gaps in the fossil record, but also a primate evolution hypothesis challenges.
    Gene study shows that humans and apes about 800 million years ago split from a common ancestor, paleontologists have been struggling to find living fossils 13 million years ago, the ancestors of modern African apes. However, scientists have found in a large number of European and Asian ape fossil evidence of that period, they found that between Europe and Asia, apes and modern African apes have some similarities. Some paleontologists inferred that the common ancestor of apes and humans was already left Africa, and evolved into several different species, and one later returned to the African continent, to become human beings and their closest primate relative common ancestor.
    However, the emerging new evidence seems to undermine the rationality of this theory. Because of this new species of ape found in Kenya living in Africa is not alone, most recently in Kenya also found evidence of another ancient African ape. Which I think it is talked about in the last slide of the video.

  2. As you stated evolution has been a gradual process that has led to us. So many generations of our species have come and gone in order to for us to be where we are in our evolutionary state. I however do not believe we are the pentacle of this great evolution process. We have room for improvement as a species and it will take many more generations down the road to see just how much more we can evolve. You also mentioned that most people have the notion that we have evolved from apes. However, we know this is not true because apes themselves are on a separate branch on the evolutionary tree. Yet most see human evolution as a linear phenomenon and fail to see how much more complex it is than that.

  3. Hello, I think your blog post was very informative and a very good summary of the information from this week’s lecture and readings. When you look at what the human race has become and how fast we seem to evolve technology, infrastructure, cities and really just change most things about the earth, it’s humbling to realize how long it took for us to become us. To think how short of a time our species has been around and who knows how much longer it will be. Aside from all of that, I definitely agree with you that I thought the most interesting thing from this lecture were the videos on Ardipithecus Ramidus and Australopithecus Sediba. I for one had always assumed that our common ancestor with primates was something that pretty much just looked like a primate. The video did a really good job in enlightening me to the fact that it really was not a primate of any kind that is alive today– because primates themselves have also been evolving for millions of years.

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