Pages

Friday, February 24, 2012

The Essentials: Skin, Kidneys and the Rest of the Inconsequential Organs


If you’ve ever received an email from me composed on my iPod you may have seen one of my favorite quotes.  The excerpt is from a The Lives of a Cell by Lewis Thomas and the extended passage reads as follows.
“Nothing would save me and my liver if I were in charge, for I am, to face the facts squarely, considerably less intelligent than my liver. I am, moreover, constitutionally unable to make hepatic decisions and I prefer not to be obliged to, ever. I would not be able to think of the first thing to do."
I like the respect and admiration for the complexity and internally programmed aptitude of the human body Lewis expresses, but I’m most impressed with the humility that comes from an appropriate view of science.  In light of the quote, and the light it sheds, why create a post title that depicts the body with such contempt? My text book told me so.
When reading in Essential Cell Biology about how genes and genomes evolve, the first point the authors make is that in terms of evolution our body doesn’t matter, only our germs. Again a clarification is needed. 
There are two basic types of cells in humans (and mammals and other organisms): somatic cells and germ cells.  Somatic cells make up the bulk of the body including skin, kidney, liver, heart, brain and bone. Basically everything except sperm and eggs are somatic cells. So that just leaves sperm and eggs in the category of germ cells.  Germ cells are the reproductive agents of the body and therefore the only cells of any consequence when passing on genetic information.  As my textbook puts it, “In this sense, the somatic cells can be considered to exist only to help cells of the germ line survive and propagate.”
Of course germ cells have all of the information that lead to somatic cells, but anything that happens after the line blossoms into a body will not have an impact on the next generation of reproductive cells that follow. The only events that can impact the germ line are sex and mutation.

No comments:

Post a Comment