A Evolução da Neoplasia

Anima Anwar

Dr. Hodges-Simeon

AN102

25 March 2014

Technology for Uncovering Fossils

One interesting topic emphasized in the “NOVA: Becoming Human” video was technology. The technological devices used to uncover fossils and create visual models/examples were revolutionary. When Selam, the fossil similar to Lucy, was uncovered, it was hard to determine the details of the fossil. It was dated back 3.3 million years ago and stuck under sediment. It took about 8 years of scraping away the sediment with precision tools in order to finally see this skull fossil for what it really was. Other technology introduced was sculptures. While this is not considered “advanced” technology, the use of clay-like material to reconstruct the muscle forms on the fossils provided a visual comparison to human faces. For example, the reconstruction of the turkana boy’s head showed that there was still a significant protrusion of the snout. Another instance where technology proved to help visualize the fossils were in the computerized movement example. Humans were asked to run while computers were tracking their movement. Scientists would then use these human movements as reference. Scientists could then replace these human movements with that of the predicted turkana boy’s movements. Turkana boy’s pelvis inferred bipedality, and therefore using human references, scientists created computer-generated locomotion examples. The computer generation illustrated that, while turkana boys movements were not nearly as fast as humans, they were still closer to human movements than that of apes. Another technological introduction in the video was a digitation of a skull using a pen-like instrument. This instrument created a 3-D image of a Neanderthal skull on the computer that was able to rotate. This was done for a young Neanderthal’s jaw bone as well. These technological advances make it so that scientist’s from all over the world can compare their findings and keep track of these priceless items.  

Brain Size and What Lead to Humans

 

Lucy, Sahelanthropus tchadensis, Orrorin tugensis, Ardipithecus ramidus, Kenyanthropus platyops, and Australopithecus afarensis were all bipedal. However, they all had chimp sized brains. Endocasts indicate that chimp’s brains are fully developed at a younger age where as all the others take longer for their brains to develop. This is one main difference in the smaller brains. Also, the brains of the hominids are shaped differently. The brains of hominids like Selam and Lucy showed that the back of the brain are bigger. In S. Tchadensis, there is a receding back skull like that of a biped and the endocast shows that there a bigger space for the neocortex of the brain. These hominids, while smaller brained, were becoming “smarter” and their brains were rewiring. While brain size did not change for a long time, they could have suddenly developed because of environmental pressures. Another brain size reference in the video was that of Neanderthals. Their difference in brain sizes is significant because their brains are bigger than humans. However, their brains are flatter and elongated, meaning that the parietal and temporal lobes of the brain are smaller.        

Locations and Climate Change

Scientists used rocks and diatoms to determine the geology during Selam’s time. The information suggested that the area was once a lake area and not as dry as it currently is. Scientists were able to use the geology to prove that the water became shallower as years went by. Theorists suggest that once the water disappeared, the species around were forced to become smarter in order to deal with the sudden climate changes. Hominins like Homo habilus survived better in these conditions than Australopithecus afarensis. This is one theory for why the hominins brains were rewiring and also why their bipedality might have even advanced in the later stages of evolution.