[MUSIC] Human evolution has been of interest to people as long as anyone can remember. It's intrinsic to understanding who we are, where we came from, and where we are going. Now, there are many aspects of human evolution that have been added to the, the, the puzzle of knowing the history of the trajectory of the evolutionary sequence that went from primates to homo sapiens. And there is a lot of intensive research work going on, on, in that area around the world as we speak. The Awash region of Ethiopia is rich in fossilized human remains. And that's because it's a, a very large series of rivers and lakes that have been there for millions of years. And, in that process of having these water rich lowland environments it was a very important environment in which to have the early primate transition into the Homo sapien lineage. Now, that region of the world though is difficult. One difficulty is that it's very hard to get in there. It's isolated. You have to carry water and gasoline. And another thing about that region is that it's, it's often times politically unstable. So the ability to conduct science in this area is dependent upon overcoming the logistical problems and that takes just a lot of planning, and, and the other part about this is that you have to wait for windows of stability, politically, within the region to be able to go in and do the research. So, combining logistic capabilities with that political window teams of scientist over the last decade have been able to get into this portion of the, Ethiopia and, and complete detailed analysis of the primate hominid transitional remains of the fossil record in this region. But one of the most important was on a time frame that went from approximately 4.2 to 4 million years before present, and this is when we had the transition of the primates evolving into the early Australopithecus, which are the earliest of the hominid series of organisms. And within that time frame, a group of researchers have been working in the Awash region of Ethiopia, and they found a remarkable series of, of skeletal remains. And they now called that Ardipithecus ramidus, and Ardipithecus ramidus represents a very early divergence going from the early primates towards the line of australopithecus and into human beings. So, let's just review a little bit about what that, that finding yielded to us. They were able to start working their way through a series of Pliocene age deposits that were laid down around the, the margins of a large river system that was in that region. And what they were able to find is that at multiple layers within this, they, they, they found, like, a complete skeleton of this organism they called ardipithecus ramidus. And the importance of this is the following, that, we generally think of that, that normal progression of diagram that shows that something that was chimp like would evolve to something that was more australopithecine-like to something that was more early-human-like and then into the Homo-sapiens. But that's not actually a very good representation, as we see from this diagram of what was going on. Really, what we want to consider is that the idea that the gorillas and the chimpanzees are as evolved and as different from the root ancestor that we came from, as we are from that root ancestor. So, in other words, there was a root group of organisms, of primates from which gorillas and chimps and humans all evolved. And as they evolved away from that original root organism, the, which we call the last common ancestor, the E, the LCA. As evolution and the progression of time went on. The chimpanzees in particular, and the humans both evolved dramatically away from the last common ancestor. So that means that, what we all evolved from in terms of a rootstock of primates, was very different from what probably the modern day chimpanzee looks like. And as different from that early root common ancestor as we are. So, the importance here is that we haven't had much understanding of what that root organism, that, at least that last common ancestor was. Australopithecus ramidus gives us a snapshot that took place just after the diversification, or the branching away in terms of the phy, phylogenetic tree of the chimps in one direction and the humans in the other. Now, what they find in this Ardipithecus ramidus? One of the things is, as you can see in this diagram, that the feet have a large toe that's actually projecting out the lateral side of the foot. And so that means that these were organisms that could not run like we could, but they could do something we can't do, which is, they could climb very well in trees. So they had this, this thumb-like extension which was their big toe that came off on the middle side part of their foot which allowed them to grasp tree trunks and, and, and branches as they, as they moved through the trees. And that's very important to us because in this time period, the, kind of, the, the picture that was presented before the work of Ardipithecus ramidus was presented is that, humans, and the Australopithecus, lineage, that they were living in savannas, large grassy areas that were almost devoid of trees. The structure of, of, and, and the short for the organism, Ardipithecus ramidus is called Ardi. The, the foot structure of Ardi tells us that, it had to have lived in trees. So that means, instead of an open savannah, it was actually a arboreal, or, or tree, rich area, a forested area, in which the, this early evolution took place. Another one is the structure of the hands. Ardipithecus ramidus has very long, slender hands, and the bones are fragile, and they're not very robust. They're not very strong. And there's, they aren't suited for knuckle walking. So in both the gorillas and the chimpanzees knuckle walking is a, a, a characteristic that they both possess, and it takes very rigid and shorter and, and very strong bones. Ardipithecus ramidus does not have that capability of knuckle walking, and in fact their hands are slender like ours, but they're actually much larger. So, they aren't adapted at all for knuckle-walking. So two things that this brings to the, the table for us which is dramatically important. Number one is the age, and that's at 4.2 million years we had already beginning to evolve, and that was after branching away from the root ancestor. The second one is that the Ardipithecus ramidus evolved in a, in a forest. And the third one is that they were not knuckle walkers, and so that means that some of the characteristics that we think of in terms of early last common ancestor for humans, something that's chimp-like, something that's a knuckle walker, something that has a very different kind of lifestyle from, from modern day humans. It doesn't fit the picture anymore because Ardi proves to us that those characteristics of knuckle-walking, were, was a trait that evolved after the last common ancestor with human beings. So, Ardipithecus ramidus has given us a brand new snapshot and a fundamentally different understanding of, of hypothesis that are now going to be tested vigorously for the next several years. And it's, it's painting a very, very different picture for us of that early evolutionary transition going from the primates into the lineage of Homo sapien. And it provides for us a, a very important context then. For seeing how the evolution of these organisms actually provided us with a whole series of intermediate steps that, that, that make sense in terms of the morphology and the ecology in the environment in which these early homosa, hominid lines were evolving [MUSIC]
