Friday, December 19, 2014
Part III- Chapter 23-38: Question 11
Explain Van Valen's theory that HeLa cells are no longer human. Was his theory accepted by the scientific community? According to Stevenson, why did scientists develop the argument that HeLa cells are no longer human? Who do you think makes the more persuasive argument, Van Valen or Stevenson?
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Because cultured cells are placed in different environment conditions and are exposed to different chemicals, cells alter their DNA code, just like in the human body. During cell division, these cells with altered DNA code then pass the changes on to the daughter cells. Since HeLa cells were distributed to many scientists around the world, HeLa cells would produce different HeLa cells; however, all of those cells came from a common ancestor. When Van Valen, a evolutionary biologist at the University of Chicago, found out that HeLa cells were slightly different, he proposed a theory: “HeLa cells are evolving separately from humans, and having a separate evolution is really what a species is all about” (Skloot, 2010, p. 216). Researchers then proposed a different name to label the HeLa cells. They proposed that the name should be changed from “HeLa” to “Helacyton gartleri” (cyton = Greek word “cell”, gartleri = Stanley Gartler—he dropped the “HeLa bomb”). The scientific community was neutral to his theory; no one challenged it, but no one supported it; therefore, Henreitta’s cells were still considered human. However, in the modern scientific community, scientists argue that it’s incorrect to claim that HeLa cells are related to Henreitta, because since HeLa cells have performed cell division for a long time, the DNA of HeLa cells isn’t identical to Henrietta anymore. For example, when Robert Stevenson, a researcher who devoted much of his time to manage the HeLa contamination, heard about Valen’s theory, he said, “’It’s just ridiculous’” (Skloot, 2010, p. 216). He believed that scientists came up with the idea that HeLa cells aren’t human, because scientists find it easier to do experiments on a species that’s not human. I think that Stevenson’s argument is more persuasive, because as he said, “if you could get a sample from Henrietta’s body today and do DNA fingerprinting on it, her DNA would match the DNA in HeLa cells” (Skloot, 2010, p. 216); therefore, disproving Valen’s theory.
ReplyDeleteSkloot, R. (2011). The Immortal Life of Henrietta Lacks. New York: Broadway Paperbacks.
I also agree with Karen. I believe that Robert Stevenson's argument was more effective. Although Henrietta's cells were exposed to chemicals and other things that could have caused DNA changes, all the new generation of cells that came from Henrietta's original cells are still human. Just because these daughter cells evolved throughout the years, does not mean they are no longer human. Yes, their DNA might be different, but that does not mean anything. The only difference that makes these daughter cells different from the original HeLa cells is that they evolved in order to adjust to the environment they were put into.
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