Spotlight on Students: Understanding Paleoanthropology

The following pieces are written by students who were enrolled in SA 202: Introduction to Anthropology.  In one of the course assignments students were provided a scenario where they had to imagine that they were paleoanthropologists who were asked to revise a press release a student composed for their recent discovery.  The following works are the students who provided the most exemplary submissions.  Please show your appreciation for their hard work through the comments.

By: Nicholas Howser

Dear Student,

As I was looking over your press release for our newly discovered species, Homo lincolnenesis, I noticed some errors in the classification of this species as being a part of the genus Homo. This specimen does have a large cranial capacity, and since “Genus Homo [is] characterized by enlarged brain” (Welsch et al., 2017), it would make sense to, at first glance, believe that this a part of the genus Homo. However, the rest of the morphological characteristics of this discovery beg to differ, giving evidence that this is most likely a transitional species due to it sharing features from both Australopithecine and Homo genera.

The first indication that this is a transitional species, and not something definitively part of the Homo genus, is the placement of the foramen magnum. The foramen magnum is the “opening at the base of the skull (cranium) where the spinal cord enters and connects to the brain,” (Welsch et al., 2017). As the Homo species evolved, their foramen magnum changed location from the back of the skull down to the bottom. The foramen magnum’s change in location is vital to the change from quadruped locomotion to bipedal locomotion, due to the fact that a fully bipedal creature would not use their arms to move around, so their spinal column would go straight down, like yours and mine. A creature that has not yet fully abandoned climbing in trees for walking on the ground would still have a slightly displaced foramen magnum, like our lincolnenesis does. Its foramen magnum has not quite reached the base of its skull, meaning there was still a very likely chance it had not abandoned climbing.

The second indication was the height (or stature) of our fossil. Judging from the fact that our specimen had a gracile, or “a body of a slender build” (Welsch et al., 2017) stature, an Australopithecine characteristic, it is very unlikely a member of the Homo genus would be short and slender. Similar to a monkey, the Australopithecines would be very short in stature, due to the idea that they would be still climbing trees and not have developed the need height to reach things. Australopithecine however, were evolved enough to make tools, as they had “hands able to manufacture tools” (Welsch et al., 2017) even though they have never been discovered with tools. This could mean that if they made tools, they would not have made them out of something that lasted, like rocks, and instead could have sharpened sticks.

The third indicator of is the size of the arms in relation to the body. According to the slideshow Human Evolution Power Point, slide 13, Australopithecus afarensis has the primitive characteristics of long arms and short legs. On the very next slide, you can see a comparison of the Australopithecine versus a Homo species. The diagram on that slide shows a clear comparison that it is easy to derive that an Australopithecine has a much larger arm to body ratio compared to a human, due to the fact that there is a high likelihood that these long arms were used to reach distant tree branches when climbing.

While you were correct in identifying some of the features of this specimen as Homo features, such as the large brains and the bowl-shaped pelvis, stating that this fossil is 100 percent of the Homo genus is incorrect, as the foramen magnum’s location, the arm length in comparison to the height, and the short and slender stature are more so traits of the Australopithecine genus. Therefore, it is clear that from the mix of these characteristics, we can draw the confident conclusion that this is much more likely a fossil of a transitional specimen, on its way to becoming a full member Homo genus. Have a wonderful day.

Works Cited

Welsch, Robert Louis, et al. Anthropology Asking Questions about Human Origins, Diversity, and Culture. Oxford University Press, 2017. (Welsch, Vivanco, & Fuentes 2017)

Unknown Author, Human Evolution PowerPoint, 2007

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By: Kimberly Hill

Greetings Student!

I want to thank you for taking the time to participate in the press release of the new discovery Homo lincolnenesis. Such a major discovery and exciting time for our school. With this new discovery and information we have studied regarding paleoanthropology, there are a few things I would like to go over. I understand that there is a lot of material that we have covered and it can seem confusing. I want to ensure that everyone understands the material and the process of how paleoanthropologist study fossils and classify them. I’ll walk through some of major steps that help determine a Genus and why these key elements are important. Please review the information provided below in reference to our press release. I took the time to outline the information that was provided both correctly and incorrectly. I also broke down the review of fossils as related to the press release and how it pertains to each specific genus. This can serve as a learning tool for all of us to use as a reference.

As paleoanthropologists, we take pride in all of our work and discoveries. We strive to provide the most accurate information possible. I want to discuss some of the key pieces of morphological evidence that are examined when determining the genus placement of a new species. First, you want to determine the size of the species’ brain. “There will be various modifications” (Welch et al., 2017:199-200) according to our text. The modifications mean that the shape of the skull and brain size varies with different Genus and species type. Other critical aspects of the species include pelvis shape, arm length, legs, and jaw/teeth placement. These are just a few of the major characteristics to look for when identifying or classifying new species.

During our press release you mentioned the species body structure/shape, brain size, foramen magnum placement, and pelvis shape. You also identified this species as definitively Homo. Let us break down each of these characteristics and see if the information that we provided was accurate to the genus Homo. “A Homo species must definitively have a large cranial capacity.” (Welch et al., 2017: 201-203) I like that you were able to correctly identify the large brain regarding this species. Australopithecus species had smaller brain sizes when compared to the Homo species.

Their body structure is roughly 5’6” tall and they have a forward-placed foramen magnum. In reference to size difference, “Australopithecus were roughly 3’11” to 4’7” tall” (Welch et al., 2017: 202-203), which means that the Homo species were taller than the Australopithecus species. This characteristic allowed the Homo to stand up straighter and not slouch over while walking. By identifying the body shape as shorter it was incorrectly stated that the new species is definitively Homo. You indicated that the newly discovered species has a posterior foramen magnum, but this is incorrect when identifying a species as part of the Homo genus. This statement is false because to the Homo species were able to stand erect. The Australopithecus species, however, were competent bipedal had a posterior facing foramen. This characteristic made them slouch and wobble while walking.

When identifying the bowl shaped pelvis and short stature of our newly discovered species these characteristics fall under genus Australopithecus. The Australopithecus species are classified based on their pelvis shape and ability to be arboreal with a bipedal gait. Having this allowed the species to walk on two legs but not erectly. As the species started transitioning to become more bipedal, we started to see a shift in the positioning of the pelvis.  What we saw is that the pelvis bone began to shorten and reposition its hip blades. This was an important reconstruction as this improved the movement of the muscles which stabilize the pelvis during bipedal walking. Genus homo did have a curved, basin-like pelvis. When comparing these specific characteristics from each species we can see how they differentiate. When identifying the new species as having long arms this is also referring to the Genus Australopithecus. In the Genus Homo, “their arms were shorter relative to their legs and their legs longer relative to their body.” (Welch et al., 2017: 204-210).

The characteristics listed above are important when identifying a species because these allows us to see what part of the lineage a species fall in. Due to this particular species showing characteristics of both Australopithecus and Homo it is safe to conclude that the fossils were of transitional species. What this means is that this species began readapting to its new environment and with that came changes to its bone structure. It no longer spent its time roaming through the trees, but now starting to walk on two legs on the ground. This gave them a slight disadvantage from its predators, because they could not quickly retreat from them. The good thing about transitioning to a bipedal species is that you are able to see your predators before they attack and are able to carry items

I am so glad that you were able to experience conducting paleoanthropology field work and identify key morphological evidence. The information can be a lot to remember and sometimes it is easy to confuse different species. Remember, keep up on your notes and research. The more you study and become familiar with the fossils, lineage and terminology used, the easier it will be to identify different species. I look forward to working with you, again. If you have any questions or want to follow up on additional ways to familiarize yourself on paleoanthropology, please stop by my office or contact me via email.

Best Wishes,

Professor Hill

Works Cited

Anthropology: Asking Questions About Human Origins, Diversity, and Culture

Robert Welsch-Luis Vivanco-Agustin Fuentes - Oxford University Press – 2017