Student 1
For me, pigmentation is an interesting topic as it deals with the coloring of skin. There is varied skin pigmentation in the world that is found across all races (Avise & Ayala, 2010). As a young child, I had always been baffled by the varied skin colors I saw. However, now that I am grown up, I can understand the variation. Scientists affirm that pigmentation is as a result of genetic inheritance where modified mtDNA of a woman is passed through generations. Research explains that human pigmentation is a result of natural selection where the skin is adapted to adjust its levels of pigmentation with the UV radiation (UVR) it is exposed to (Avise & Ayala, 2010; Jablonski & Chaplin, 2010). The dark pigmentation is explained as being the result of high UVR for inhabitants living near the equator while the lighter pigmented skin was an adaptation of the skin to sustain cutaneous photosynthesis of vitamin D3 in low UVB environments (Jablonski & Chaplin, 2010). I agree with you that variation in pigmentation is as a result of natural selection where man evolved with regards to UV levels in their environment.
References
Avise, J. C., & Ayala, F. J. (2010). Human skin pigmentation as an adaptation to UV radiation. In In the Light of Evolution: Volume IV: The Human Condition. National Academies Press (US).
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Jablonski, N. G., & Chaplin, G. (2010). Human skin pigmentation as an adaptation to UV radiation. Proceedings of the National Academy of Sciences, 107(Supplement 2), 8962-8968.
Student 2
Scientists affirm that evolution is a continuous process that began eons ago. The question of what makes us different from our archaic ancestors is one that has been debated over time and has interested me as well (Clinton, 2015). The evidence in evolution is found in the remains of previous species of man. Although there are many differences between the modern man and the previous species, skulls are commonly used as they have obvious discrepancies and have survived degradation over the years (Climate Effects on Human Evolution, 2019). Homo sapiens indeed has a relatively smaller brain size as compared to his predecessor, homo neanderthalensis whose brain sizes are 1350 and 1500, respectively (Clinton, 2015). Research shows that people who live in the cold have larger brains as compared to those living in warmer regions which would explain the differences in brain size as the ancestors of modern man lived in colder regions (Climate Effects on Human Evolution, 2019). Other than these, there are evident differences that can be observed in the skulls, face and brain cavities of modern man and his predecessors. The modern human face is relatively smaller and less retracted than that of homo sapiens and other predecessors (Clinton, 2015). I agree that these evident evolutions occurred due to human necessity and climatic changes.
References
Clinton, K. (2015) Average Cranium/Brain Size of Homo neanderthalensis vs. Homo sapiens . Retrieved from https://www.cobbresearchlab.com/issue-2-1/2015/12/24/average-cranium-brain-size-of-homo-neanderthalensis-vs-homo-sapiens
Climate Effects on Human Evolution. (2019). Retrieved 8 November 2019, from http://humanorigins.si.edu/research/climate-and-human-evolution/climate-effects-human-evolution
