106 - 11 online new

Wichita State University Name: ANTH 106 Fall 2022 Tuesday/Thursday Instructor: Buchanan-Burke Lab 11 –The Genus Homo SECTION 3: The genus Homo Each fossil of a hominin represents a unique individual. Therefore, no two fossil hominins share identical morphologies. Morphological similarities can cluster fossils into the same species, but there is no rule regarding how similar fossils must be to each other to belong to the same species. Sometimes researchers disagree over whether a fossil represents a new species or belongs to a previously established species. This is especially difficult to determine because primates can have high degrees of sexual dimorphism. Males and females of the same species can look very different and establishing the sex of an individual from fossil remains can be very difficult. Therefore, a new fossil could represent the other sex of a species already established in the fossil record or a truly new species. Measures of variation (i.e., size and shape differences) can help determine whether a fossil’s morphology reasonably falls within the estimates of an existing species. In this lab, we will examine the morphological characteristics of each of the fossils and discuss the justifications for separating them into subsequent genera and species. Australopithecines Australopithecus afarensis – This is one of the oldest of the australopithecines. Australopithecus Afarensis lived between approximately 3.9 and 2.9 mya. Australopithecus exhibit post-orbital constriction that is greater than more recent hominins, but less than extant (still alive) hominoids. Australopithecus africanus – A. africanus was one of the first hominin ancestor fossils ever discovered, when in 1924 Raymond Dart excavated the Taung Child . A. africanus is remarkably similar to A. afarensis , yet we still prefer to keep them separate. Paranthropines Most of the Paranthropines were discovered in eastern Africa. The Paranthropines are known for their wide, ‘Dish-shaped’ face. This is a result of large temporal muscles (chewing muscles) that run underneath the zygomatic arches. The wide face shape combined with the robust, flat molars of the Paranthropines led to the hypothesis that Paranthropines ate mostly grasses and seeds. The sagittal crest is also a characteristic of the Paranthropines that is a result of the strong temporal muscles. Paranthropines have been classified into three species: P. aethiopicus (2.5 mya) , P. robustus (1.8-1.2 mya) , and P. boisei (2.3-1.2 mya). Early Homo

H. habilis is currently the oldest species included in the genus Homo (the oldest known specimens have been dated to ~2.4 million years ago). However, this taxon is controversial, because the specimens included within it exhibit a high degree of variation. It is not known whether these specimens truly all belong to H. habilis or whether the sample includes representatives of multiple species. Also, although H. habilis shares certain morphology, especially its limb proportions, are more similar to the earlier australopiths. Some researchers have even proposed that Australopithecus habilis is a more appropriate species name. Sagittal Crest 3.1 (5 pts) Do the morphologies between the Australopithecines and Paranthropines differ drastically? I would not say that they differ drastically but there is a difference between the morphologies of Australopithecines and Paranthropines. Most notable differences would be the teeth/jaw difference as well as a possible cranium difference. 3.2 (5 pts) How do the Paranthropines compare to the morphology of Homo ? Post Orbital Constriction Sagittal Crest Face to Vault Ratio and Prognathism

SECTION 4: Punctuated equilibrium and gradualism In 1972 Eldredge and Gould took a look at the fossil record and noticed a trend. The trend was that there were major evolutionary changes that occurred in spurts in-between long spans of time. The theory was that evolutionary changes and development would occur rapidly and in spurts, and it was termed ‘Punctuated Equilibrium’. The other side of the argument is gradualism. Gradualism suggests that evolutionary changes occur gradually and slowly over long timespans. Microevolutionary changes occur at a very slow rate which slowly build up to a macroevolutionary change. 4.1 (5 pts) What are some of the problems regarding punctuated equilibrium when one looks at the fossil record? Some fossil records indicate that there is slow gradual changes over time rather than rapid changes in a short period of time. There is also no explanation as to how and why these drastic changes could occur so quickly. 4.2 (5 pts) Is gradualism a better or worse interpretation of the fossil record than punctuated equilibrium? Why? Right now, the fossil evidence seems to support punctuated equilibrium rather than gradualism as a more accurate interpretation of the fossil record. However, it is important to note that neither idea has been proven 100%. Therefore it is important to keep an open mind about both interpretations when it comes to trying to understand the complexities of evolution. 4.3 (5 pts) Could punctuated equilibrium and gradualism be combined to form a new intermediate hypothesis? Explain why or why not. I think we can blend punctuated equilibrium and gradualism to form a new intermidiate hypothesis. Evolution could happen slowly over time or in sudden bursts, depending on the environment and it’s challenges. This approach acknowledges both sides, and can help form a sophisticated guess that embraces the complexity of the evolutionary process.

Take-Home Assignment: Visit https://humanorigins.si.edu/evidence/human-fossils/mystery-skull-interactive Identify Each of the Mystery Skulls and provide an explanation for how you correctly (or incorrectly) identified each fossil. 1. Mystery Skull 1- I chose Homo Neanderthalensis from France 60,000 years old. Because of the prominent brow ridge, large face, and the cheekbones that are angled back from the nose. 2. Mystery Skull 2- I chose Homo Habilis from Kenya 1.9 million years old. Because of both having smaller teeth, slightly sloppy face, smaller braincase, and seem to be slightly similar in shape and size. 3. Mystery Skull 3- I chose the Homo Erectus from Indonesia because they are both portraying a elongated braincase and a bigger brow ridge. I chose Indonesia over China because the shape/size seemed to have matched more.