Part I: Humans are the only mammals to have lived in the most extreme environments from remote islands, to deserts, and high mountains. For over 1,000 years the Bajau people, often referred to as sea nomads, have lived an almost entirely marine-dependent existence, gathering food and resources by freediving up to 230 feet without an oxygen tank. These freedivers spend approximately 60% of their working time under water. Scientists sought to determine whether the Bajau’s freediving abilities were the result of natural selection for certain genetic adaptations or if these abilities were due to practice and training within the Bajau’s culture during an individual’s lifetime. They designed an experiment comparing the Bajau to the Saluan, a nearby population that does not traditionally freedive. Scientists found that the Bajau had significantly larger spleens than the Saluan, even in individuals who were not freedivers. Watch the following video or review the following article:
● Ilardo, M., Moltke, I., Korneliussen, S., et. al. (2018, April 19). Physiological and genetic adaptations to diving in sea nomads. Cell, 173(3). https://www.cell.com/cell/fulltext/S0092-8674(18)30386-6
Then, address the following questions.
1. Why do you think scientists measured spleen size? Based on the reading, what role do you think the spleen plays in an individual’s ability to dive?
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2. How does the experiment measuring spleen size support the following hypothesis: “The freediving ability in the Bajau is a result of natural selection”? Give an example of a more specific, testable hypothesis for the larger spleen size and how it may contribute to the extraordinary diving abilities of the Bajau.
Answer Here
Part II: List the physical evidence of evolution the authors discuss in your textbook. Then, choose ONE of these and summarize it in your own words.
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Part III: While on an ecological trip to the tropical rainforest, you discover a small unfamiliar object that looks like a living organism. You think it may even be a new species. What characteristics would you look for in order to decide if your discovery should be classified as a biotic organism? Apply each of these characteristics of living things from Unit 1 and identify your “object” as biotic or abiotic.
Answer Here
Part IV: During this week, you reviewed the characteristics of living things and the characteristics of our species, Homo sapiens. As we have learned, humans have biological and cultural adaptations that enable them to survive in even remote areas of our planet. Describe one cultural and one biological adaptation exhibited by humans where you live. What cultural challenges might you face if you had to live among the Bajau? How might someone overcome some of the challenges listed in your response?
