By Jessica Meng
Do you remember when you were a child and went through a “fossil” phase? Maybe you’re still in it. Teachers fascinated us with stories about dinosaurs and mammoths and saber-toothed cats, and we would go scrambling about, digging holes in our backyards in hopes of finding a skull of some gigantic prehistoric beast. And then, not really knowing what a fossil looked like, we would dig up some weird pointy rock and excitedly say it was a dinosaur tooth.
Of course, most of us were greatly unsuccessful in this quest for paleolithic remains; however, a graduate student from Ethiopia, Chalachew Seyoum, managed to realize this dream.
In 2013, Seyoum found a human jawbone, with five teeth intact, in the Afar region of Ethiopia, near where Lucy, the famous 3.2 million years old Australopithecus Afarensis, was found. The bone was poking out of the eroded side of a hill. This jawbone is 2.8 million years old, 400,000 years older than scientists first thought the human race was.
Yet, this is not the only reason why this was such a remarkable find; earlier, humans only found fossilized remains of the 3 million year old Australopithecus, and then the remains of the genus Homo, our genus, was found to be 2 million years old- and nothing was found in the gap between. It seemed almost as though Australopithecus just dropped off the face of the planet, and Homo randomly popped in.
Of course, this is never the case; scientists knew that there must have been a transition between the two, but one was never found. Despite the fact that only a jawbone was found, scientists are sure that this marks a transition between the more apelike Australopithecus and the first humans. Brian Villmoare, a paleoanthropologist at the University of Nevada and the leader of the team that made the discovery, states that “…it’s a reduction. It’s becoming ‘less’. The teeth are not these big blocky rectangular things, they become more slender.” In other words, the jaw, although not identical to ours today, was considerably smaller than the jaws of the Australopithecus; somewhere in between the two. What could have caused the reduction in jaw size? Well, scientists theorized that huge, powerful jaws and teeth were made unnecessary by the development of stone tools that grinded up, cut, and pounded the food, making it easier to chew. In the future, we may find even more human remains demonstrating the intriguing transition from the Australopithecus and the Homo.
What was life like on Earth 2.8 million years ago? Well, other than our jaws changing shape and our bodies in general transitioning into the humans we are more familiar with today, it was also towards the end of the Pliocene epoch and the global climate was cooling down. During the Pliocene, the Indian and Eurasian plates were colliding, forming the Himalayan mountain range. The Isthmus of Panama also formed, allowing for creatures in North and South America to mingle. In addition to this, the land was becoming more arid, and analysis of the sediment in which the jawbone was found suggests that the land was dry and grassy, with few trees. It was this very environment that led to the success of bipedal hominids, who could look over the tall grass and walk farther distances while being hands-free to carry things.
