Blog Five: Human Evolution

Looking at different human remains and their fossil record can tell us about who we are today and how we got to this point. This week’s lectures focused on the different traits that came about, their uses, the ever changing environment that the early hominins lived in, and the different methods of dating the fossils. I found the topics this week to be really interesting, especially learning about some of the changing traits from one to the next, and the advantages and disadvantages that they had in certain environments or under certain conditions.

One trait that I found highly intriguing was the skull. The location change in the foramen magnum to be under the skull indicates that the creature would walk in a bipedal way, instead of on four legs.  The skull also has a secondary trait, which is the overall size of the skull. We learned that chimps and other non-human apes typically have a relatively small brain, usually 450cc or smaller, while a modern human has a size of about 1200cc. Both the change in head size and in the foramen magnum show a progression in bipedalism, and an increase in complex thought. The change in head size also correlates with the use tools as well to show the increase in this thought. These tools help anthropologists learn how the early human thought, and how this thought grew into the modern human’s abilities of complex thought. The wide variety of earl hominins goes to show how some lines are able to adapt to the conditions around them, and how some have difficulty with it and they end up dying out.

Another trait I found interesting was the change in teeth. In early primate-like hominins you see larger canine teeth, which are useful for fighting if one were up in the trees with all of their hands occupied with holding on. As these early hominines started coming down from the trees, they no longer had such a huge need for large canines because they could do more work with their free arms and hands instead. The reduction of the canine teeth is mainly shown in Australopithecus Afarensis, which we know from the Laetoli footprints that they were bipedal and also lived in less treed locations similar to the Serengeti plains, as well as in marshy areas. In later Australopithecines you can see the transformation to more modern looking teeth, which are good for both chewing (molars), and ripping/cutting action (incisors). You can learn from the diverse environmental conditions that they lived in, that these type of teeth would be highly useful to eat a large variety of foods without expending a ton of energy trying to eat them. Anthropologists can make connections between the teeth of these individuals, and the type of foods they ate by referencing the teeth and the type of environment they may have mainly lived in. We can see from Paranthropus that they specialized in chewing, and that they spent a majority of their time doing so due to the large mandible and sagittal crest and large molars.

The large diversity of early hominins helps anthropologists gain a better understanding of how humans have evolved into their current state, and they can also get a pictures of what early traits “failed” and the reasoning on why some of these branches went extinct. I found this week’s lecture to be very interesting because of the large amount of changes that occurred with our early ancestors.

3 thoughts on “Blog Five: Human Evolution

  1. Hey Kathleen!
    I really liked your blog post! I also thought that this week’s lectures were really interesting and insightful into human evolution. I like how you talked about the skull and brain size. I like how you used numbers in your comparison, that chimps and non-human apes had brains of about 450 cc, whereas humans have brains of about 1200 cc. To me this seems like a huge difference and the numbers really helped me with perspective. It is interesting, because it is important to remember that as much as humans and chimps seem similar, the real difference does lie in brain capacity. Think of all the things that humans can do that chimps can’t, because of our complex brain function. I would be curious to know the brain sizes of some other animals, just because chimps seem like some of the smartest animals that I can think of, so I’d like to know the difference in brain size between like a dog and a chimp. I think that would interesting.

  2. Hi Kathleen,
    Thank you for your well thought out and written response to this week’s blog assignment. You made a number of excellent points throughout the blog post. I also found that the qualities and characteristics of hominin skulls and teeth can provide a significant amount of information about the lives of hominins (what was their diet, were they capable of complex thought, etc.). It is amazing to think about the amount of change that the hominin brain has experienced. As you stated, the hominin brain increased in size from 450cc to 1200cc. In association with that increase in brain size were the evolutionary developments of bipedalism and tool making/complex thought. Once again, excellent job on this week’s blog post.

  3. The two traits you picked are some of the most interesting, I think. The skull location in relation to the spine also piqued my interest. I think it’s fascinating how scientists can tell about when our ancestors and those related to our ancestors began to walk upright. It’s a logical strategy but I never would have thought of that as the tell-tale sign.
    I also think it’s interesting that the actual size in skull is relative to brain capacity, more complex thought and thus the ability to create and use tools.
    I agree that the development and change in teeth size and shape is also indicative of our evolution. This shows a number of things, I think, including the change in diets which, in turn, shows the change in environment in which they lived.

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