Monday, August 1, 2022

Physiological and Genetic Adaptions to Diving In Sea Nomads

Environmental & Science Education, STEM, Biological Evolution

Ed Hessler

The BBC Reel has a video (5m 33s) about "a semi-nomadic tribe of fishers with extraordinary freediving skills." They are the Sama-Bajau of SE Asia. 

The introduction includes that shop-worn phrase, "research has shown that their anatomy has evolved to help them...." This research, as is all too usual is not given much time in the film and no scientists involved in it are included.

So I looked for the data, evidence, how it has been interpreted, etc. These are numbered below and range from general to technical papers.

One.  Elizabeth  Pennisi in a news comment in Science (April 19, 2018), * reports on research reported in CELL (173 (43), April 19, 2018 by Melissa A. Ilardo et. al., in the paper titled "Physiological and Genetic Adaptations to Diving in Sea Nomads." Here are the key findings from the paper.

--The Bajau, or "Sea Nomads," have engaged in breath-hold diving for thousands of

--Selection has increased Bajau spleen size, providing a (reservoir pf oxygenated red blood cells), i.e., an oxygen reservoir for diving.

--We find evidence of additional diving-related phenotypes under (natural) selection.

--These findings have implications for research on hypoxia research, a pertinent medical issue.

The paper is technical but there may be segments that interest you such as data, charts, graphs. The paper includes a video abstract and a graphical abstract. The discussion includes a statement on what the results suggest overall. (I've removed the references which you can find in the discussion.)

Overall, our results suggest that the Bajau have undergone unique adaptations associated with spleen size and the diving response, adding new examples to the list of remarkable genetic adaptations humans have experienced in recent evolutionary history. Similar to other of the most extreme adaptations human have experienced, such as adaptation to diet associated with pastoralism) or shifts in environmental availability of food resources), these genetic adaptations have emerged as a consequence of new cultural practices, illustrating that human culture and biology have been co-evolving for thousands of years.

Pennisi's discussion includes comments on consequences most mammals experience when "their faces hit cold water"; how the measurements were taken; DNA comparisons; comments by skeptical scientists, including limitations of the research; and possible biomedical applications. Pennisi's comments are preceded by a video on recent human adaptations to living in less-oxygenated environments.

Pennisi notes that "Mark Aldenderfer, an archaeologist at UC Merced who was not involved with the work," said, 'Perhaps the biggest takeaway from this paper is that natural selection continues to work on human populations.'"

Two. And this essay from The Conversation provides a discussion for generalists on the paper in Cell by Ilardo et al.

Three.There is a splendid Science Friday for April 20, 2019 conversation with Dr. Ilardo (17m 34s) in which the research and its meaning is discussed with the lead author. It is worth the listen providing insights on the science.

Dr. Melissa Ilardo is currently employed at Maze Therapeutics. She also is an Adjunct Assistant Professor at the University of Utah.

*At the top of Pennisi's column is a video (2m 44s) on human adaptations to living in oxygen deprived conditions. 

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