Hominin traits are quite useful in helping scientists construct a history of the evolution of the modern human. Some of the hominin features that can inform us about modern human biology are bipedalism accompanied with the positioning of the foramen magnum, a face that sticks out a little more, and smaller canine teeth. According to fossilized skulls, early hominins like Sahelanthropus tchadenis who have a brain about a third of the size of a human show the evolution of the human brain in both size and structure. We see that having flatter faces is a more primitive feature. This is most likely due to the development of a larger pre-frontal cortex in more modern species. The pre-frontal cortex is attributed to human qualities like personality and what we determine higher judgement that makes us “civilized”. Walking on two legs is also an evolutionary change that we begin to see crop up even before the development of a slightly larger brain. Bipedalism is a pivotal point in evolution because it marks the end a long era that was quadrapedalism. Even if it was only for a fraction of the organism’s life, walking on two legs had never been seen before Sahelanthropus tchadenis. This is advantageous because it frees up the arms to do other things rather than having to use them for movement. Since they are still very primitive, they do all of the things that apes did but they walk on two legs. The foramen magnum is now more towards the bottom of the skull, therefore the spine is positioned directly below the head for a more upright posture. Humans are now well adapted to only walking on two legs and bearing weight on one leg at a time while walking. This feature of head positioning leads into the next feature of smaller canines associated with bipedal species. Larger canine teeth were needed for defense and fighting because it was better to lunge face first at the target and to fight with their teeth and bite the opponent. However, with an organism that is upright, it is not in their best interest to lunge at something teeth first because their head is no longer the most fore-front aspect of their body and the canine teeth actually transition to incisors used for being omnivorous. Each of these traits can be seen in varying degrees throughout the different species over time, eventually leading to what we see as the contemporary human.
Humans have only been around for a few thousand years and can learn a lot from our not so distant ancestors. Anthropologists can pool their knowledge of the numerous intermediate species to surmise what led to their extinction and help humans make the best of our evolutionary compromises. Becoming bipedal led us to have softer bones, more fragile joints and spines, and riskier births. With the medical advancements we have developed over time, these detriments have been minimized but are still a threat to our well-being. Our spines are more exposed and fragile but this is because they have to support our larger skulls. Our larger brains have given us the opportunity to explore our extensive ancestral history and help us to assemble the best way to proceed and further the modern human race.
I like how you went step by step analyzing the many traits that have slowly changed throughout time. I especially thought that your point about how being bipedal allows the hominin to use its arms for a variety of different things, which the hominins are eventually able to use to their advantage. Using our hands is something humans take for granted, but for these early hominins, it was a complete game changer. I agree that while we have evolved in a beneficial way, there are always some compromises. Humans developed larger and more complex brains but also more fragile joints and softer bones. I think that this is fair since we have larger brains and can develop technology that can help us counter our weaknesses. Humans are not perfect, but having a large brain is such a big advantage over other animals that it doesn’t really matter.
Jessica,
Your examples of traits that help anthropologists study the evolution of humans are spot on; the transitions of foramen magnums appearing under the skull, faces becoming rounder, and canine teeth becoming less prominent are all viable traits that can be observed on various fossils. I liked how you dug deeper into the reasonings for the cessation of the respective primitive traits that correspond to the derived traits you chose. For example, you contributed that the enlargement of the prefrontal cortex over time would directly affect face shape, which is a very valid point.
Additionally, I very much agree with the point you made in your last paragraph about how studying fossils allows us to adapt our lives to our evolutionary changes. Technology, too, helps us discover reasons for physical evolutionary changes, allowing us to anticipate future changes.
I enjoyed how you explained the change in each trait – describing its change over time and why it has developed to aid human life currently. The benefits gained from an increase in brain size, as well as smaller canines, have helped us thrive in our environment but even then, there are always compromises. Because of this reliance on our brain and other humans, we are not able to defend ourselves as well in unfamiliar environments or when faced with a predator (by ourselves). As you mentioned before, our natural weapons such as our teeth and longer arms have been traded in due to our other “derived” features we have gained over time.
I also liked how you viewed the observation of other hominin species as an aid to help us learn and thrive with our “evolutionary compromises.”
Hi Jessica, I enjoyed your title: Hominins helping present humans. This week’s lecture videos and articles were very interesting. Looking at hominin features can allow anthropologists to provide insight into our ancestors and how we became the way we are today. I felt one of the most important traits that we have seen from hominins was bipedalism, seeing that evolutionary change from our ancestors that have made us bipedal. Allowing us to walk and go about our lives. Your point was interesting on the flatter face perspective, I noticed the difference in skulls of humans today vs hominins back millions of years ago. Back then they were said to have smaller brains, and our developing pre-frontal cortex would explain why our skull has a more flat look because it made room for our larger brain! Great point to make Jessica, I did not think of that!
Hey Jessica! I found the way that you structured your post, as well as the content, very fascinating! Prior to this class, I had no idea that species evolved according to a “mosaic evolution”, in that our unique traits, like bipedalism and brain size, occurred in a certain order and not all at once. The difference in brain size between these 300-500 cc in early hominins, and as we will learn in the next lectures, Neanderthals and humans have about 1500 and 1400 cc respectively, is really intriguing to think about how significant that difference is. I had not fully understood the trade-offs and consequences of becoming bipedal, like more fatalities related to child birth, back/foot pain, etc. But in particular, I found your explanation regarding anterior placement of the foramen magnum really interesting. I had never thought about the difference in impact of a quadrupedal and bipedal lunging in attack. I knew that canines had become smaller because they were no longer really used to attack like more ape-like or chimpanzee-like hominids and hominins, but I had not visualized it in this way.
Hi Jessica!
Your comments about the bipedalism in hominins makes me wonder exactly what life would be life if we were still walking on our hands and feet. We would hardly be able to complete any task in the timely manner that we do now. I think of everything I do while simultaneously walking, such as eating, writing, reading, and so on. So many tasks could not be completed because you would have to be stationary while performing them. I believe that bipedalism is evolutionarily one of the most vital changes in human history.
Hi Jessica! I liked how you summarized the major hominin traits nicely. I found the statement about flatter face as being more primitive very fascinating. I also feel that bipedal locomotion played a big part in evolution. It was interesting to see some hominin species using bipedal locomotion. Later, we saw Lucy also used bipedal locomotion. The footprints of Laetoli were found almost identical to the footprints of modern humans. These studies helps to understand traits of modern humans. This is why the study of fossils is crucial. It provides evidence on evolution. It also helps us understand the physical differences between males and females. We can also help understand how the species were adapted to their environment based on where the fossils were located and how old they were when studied.
Hi Jessica. I didn’t know that the pre frontal cortex was connected to traits like personality and high judgment, that is interesting. You noted that being bipedal increases risks of softer bones, riskier births, and fragile joints, so weighing the pros and cons, it makes you wonder if evolution will continue to work on these issues, or if being bipedal evolved that way too quickly? We have studied that the size of our brains and skulls have evolved to be much bigger, do you think this will continue to increase, or stay where it is now? I went to the museum here at MSU a couple of weeks ago and comparing the size of fossils was amazing. If you think about it, it’s sad that we evolved to be bipedal and see forward the way we do to go on and develop issues like posture problems and “text neck”.
Hello, Jessica! I enjoyed reading your thoughts on the hominin traits that inform us about human biology. I liked how you presented your information starting with bipedalism and transitioning to the effects it had on hominin evolution. Bipedalism was the turning point for hominin evolution that allowed us the use of our hands freely. Our hominin ancestors were able to carry more food and things such as tools that improved their successfulness. The effect of bipedalism on the structure of the body can inform us about some of the drawbacks of bipedalism, such as having more back issues and more difficult childbirths. Anthropologists ability to paint a picture of human evolution through the evolution of hominins allows us to understand with much greater depth who we are and where we came from.