SC235: Human BiologyUnit 2 Assignment

Name: __
Please address each question and submit the completed worksheet to the Unit 2 Assignment
Dropbox when completed.

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 called 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 underwater. Scientists sought to determine whether Bajau’s freediving abilities
resulted from natural selection for particular genetic adaptations or if these abilities were due to
practice and training within 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:

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?
   The scientists measured the spleen size of the Bajau people to establish how this
   population differs from people from the same region, particularly the Saluan. According to

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Ilardo, Moltke, and Korneliussen et al. (2018), the Bajaus’ bigger spleen is crucial for making
more oxygen available in their blood to enhance diving.

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.
   The freediving aptitude of South-East Asia’s Bajau people results from natural selection
   because they developed bigger spleens crucial for diving. Ilardo, Moltke, and Korneliussen et al.
   (2018) find that the Bajau are traditionally seafaring and nomadic, surviving by gathering
   shellfish from the seafloor.

Part II:

The primary physical evidence of the evolution of the Bajau people in the development of
larger spleens which is 50 times the size of normal humans. This evolution has enabled the Bajau
to free-dive and stays underwater longer when collecting shellfish from the seafloor. This
development differentiates the Bajau from other people within the same region, prompting
increasing scientific studies worldwide.

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 to decide if your discovery should be classified as an abiotic
organism? Apply each of these characteristics of living things from Unit 1 and identify your
“object” as biotic or abiotic.

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Biotic describes an ecosystem’s living components, for example, organisms such as
animals and plants. Some of the characteristics that I would look for to decide if my discovery
should be classified as an abiotic organism include the physiognomies of plants and animals such
as growth, excretion, reproduction, movement, nutrition, sensitivity, and respiration.

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?
Examples of biological and cultural adaptations of humans include bipedalism and
figures of speech, respectively. Bipedalism refers to the ability of human beings to walk on their
two feet. On the other hand, establishing local languages and figures of speech helps people get
by better in new cultures. Living among the Bajau presents a cultural challenge of acquiring
information at the appropriate level for demonstrating how specific actions such as ‘no-take’
fishing zones enable them to accomplish their aspirations (Ilardo, Moltke, & Korneliussen et al.,
2018). Overcoming this challenge necessitates the reassessment of the Bajaus’ assumptions
concerning the worthwhile aspirations of what is good for them and their roles and rights in
establishing the outcomes (Baranova et al., 2017).

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References

Baranova, T. I., Berlov, D. N., Glotov, O. S., Korf, E. A., Minigalin, A. D., Mitrofanova, A. V.,
… & Glotov, A. S. (2017). Genetic determination of the vascular reactions in humans in
response to the diving reflex. American Journal of Physiology-Heart and Circulatory
Physiology, 312(3), H622-H631.
https://journals.physiology.org/doi/pdf/10.1152/ajpheart.00080.2016
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