Humans are primates; however, we are not the only primates on Earth. According to Trzepacz, Timmons, and Duobinis-Gray, “Primate classification includes animals such as the tiny tarsier, the acrobatic lemur, the flamboyant mandrill, and the powerful gorilla.” (12-2) What makes us primates is the certain characteristics we share; the main characteristic being our ability to grasp objects using our hands. Humans are further classified as hominids. This is a subgroup family of primates that have roamed the Earth for around 13 million years.
To show how similar we are to other hominids O’Neil explained, “The African apes and humans have essentially the same arrangement of internal organs, share all of the same bones (though somewhat different in shape and size), lack external tails, and have several important blood type systems in common.” Paleoanthropologists study these similarities between hominids and help piece together human evolution. Paleoanthropology is extremely important because it helps us understand where we come from and why we have certain traits that other species do not have.
The hominids have many similar traits which are why they are grouped, but they also have many different features especially concerning their skull structure. This is how we can distinguish skulls between different hominids. By measuring different features of the skull, we can determine the difference between a human, gorilla, and chimpanzee. We hypothesize that the features that are most similar to the human skull will be the closest relatives to humans. However, with this hypothesis, we are aware that features vary between humans and also other primates.
According to Parr, “The second type of configural information described by Diamond & Carey is the second-order configuration. This refers to the relative spatial arrangement of facial features with regard to one another, which is unique in every face.” Keeping this information in mind we acknowledge that measurements may not be an exact representation of an individual species.
To test this hypothesis, we measured eight different skulls belonging to unknown species. To measure the features of the skull we used calipers and meter sticks. Calipers were used for an exact length between two points on the skull, then we carefully placed the calipers next to the meter stick to find out the exact measurement of the feature we measured. The features we measured include cranial breadth, cranial length, facial breadth, facial projection length, total skull length, vertebral attachment length, total skull length, incisor length, and also canine length. To get the cranial index, we first had to measure the cranial breadth and the cranial length. After measuring these features, we then divided the breadth and length and also multiplied them by one-hundred, giving us the cranial index measurement. This simple calculation was repeated using different features to determine the skull proportion index, facial proportion index, vertebral attachment index, and canine incisor index. We used these measurements to place our skulls in order from most related to humans, to least related to humans. For example, the cranial breadth of a human is around 15.5 cm, the closest relative to humans would have a measurement close 15.5 cm.
There were several trends represented by this data. One being the similar measurements of the facial projection index. This trend shows that as humans have evolved the facial projection index has not seen a significant change like many other features of the face have. The data seems odd in a couple of places. The most distant relative to humans, skull D, has a left canine length and vertebral attachment measurements that are close to Homosapiens (humans). Our initial ranking of the skulls was similar to the correct results. However, it was very difficult to rank the skulls due to the similarities and differences in lengths that varied across the skulls. However, our group kept in mind that every individual may not be a perfect representation of a certain species. Our hypothesis was supported, the closest relatives to humans had the most similar facial measurements to humans. It is extremely important to understand the process of hominid evolution. It can explain the flaws in the human anatomy. One example of this is our S shaped spine. This shaped spine is very different than our distant ancestors and is the reason for why many humans struggle with back pain. This is also a trade-off of humans being bipedal.