Viraj's Weblog

I just finished reading Dawkins' The Ancestor's Tale, quite an amazing history of life told backwards in time. Dawkins' eloquence rivals Carl Sagan, and watching Cosmos in parallel to reading this book, I notice striking similarities. It seems the important scientists of today are restating what Sagan said years ago. Sagan was definitely ahead of his time.

In the chapter on Sponges, Dawkins talks about germ-line vs soma cells:

... germ-line cells are those that are capable of giving rise to reproductive cells and whose genes are therefore in principle immortal. The germ line is a small minority of cells residing in ovaries or testes, and insulated from the need to do anything else but reproduce. Soma is that part of the body that is not germ line -- somatic cells are destined not to pass their genes on indefinitely. In a eumetazoan such as a mammal, a subset of cells is set aside early in embryology as germ line. The rest of the cells, the cells of the soma, may divide a few times to make liver or kidney, bone or muscle, but then their dividing career comes to an end.

To consider that the genes in your germ-line cells can be traced back to the origin of life is quite amazing. But what if a cell that's supposed to stop dividing continues dividing. That's cancer. A pretty good article on mercury poisoning in Discover states:

One cause of cancer is healthy cells' growing out of control and losing their identity: They forget that they are programmed to be liver or heart cells and go rogue, not dying in the usual manner but instead continuing to replicate into more rogue cells.

Dawkins' goes on:

Cancer cells are the sinister exception. They have somehow lost the ability to stop dividing. But as Randolph Nesse and George C. Williams, the authors of The Science of Darwinian Medicine, point out, we should not be surprised. On the contrary, the surprising thing about cancer is that it is not more common than it is. Every cell in the body, after all, is descended from an unbroken line of billions of generations of germ-line cells that have not stopped dividing. Suddenly being asked to become a somatic cell like a liver cell, and learn the art of not dividing, has never happened before in the entire history of the cell's ancestors! Don't be confused. Of course the bodies that housed the cell's ancestors had livers. But germ-line cells -- by definition -- are not descended from liver cells.

Indeed it is rather incredible that cancer is not more prevalent. It just goes to show just how honed our bodies are through evolution. Any slight error in this descendency is liable to end that germ-line forever; a death of a lineage. Nature is not forgiving. The book paints a grim tale. Evolution is essentially the history of death and the honing of survivability. There are so many branches, organisms, species, individuals, that died without reproducing. So I ask, is it really important that any one individual reproduce?

Modern-day medicine counteracts the death of an individual, keeping the lineage going when in the past the individual may not have survived to reproduce. Rise in cancer is almost inevitable if we prolong the lifetime of our error-prone genes.

But if you think of the whole world as an organism, the death of lineages in the evolutionary tree is reminiscent of "soma vs germ." In this tree, some species die off. These are like the soma. They make the "liver" of the world, providing some function to the overall survivability of the world's life but ultimately dying. They are unknowingly altruistic to a much larger organism. Then you have the species that produce offspring. These are like the germ-line cells, continuing their path through evolution. The soma are the cells that die in our webbed embryological hands to make way for fingers. Both their life, and their death, serves a purpose. Might looking at the world, or even the universe, as one big living organism with internal organs and an embryology of its own, lead to a different understanding of life as we know it?

Hulu has all of the episodes of probably the greatest science show of all time: Cosmos. The only annoying thing is the commercials.

Some really good TED talks:

• Wearable tech
• Importance of Play
• Dirty Jobs