I saw recently that Christopher Hitchens died of throat cancer. Very sad. I really liked several of his essays for GQ and was inspired by his Enlightenment thinking and the way he bulldogged for atheism, not making concessions, even for the soft forms of religious belief. What did they call him in the obituaries, anyway, a "public intellectual?" That sounds dumb. He was much more than that.
But another obit was more important to me personally. Lynn Margulis, who formulated the theory of bacterial endosymbiosis, died after a stroke. I remember learning about the theory when I was 12 or 13. Until around that time I had pursued a passionate but undisciplined interest in living things. It was at that age that I learned about the real stuff, the molecules of life and deep time and the mechanisms of evolution. As the theory goes (and it is now very much supported by the evidence), eukaryotic cells had their origin in an event where cells took on other cells that eventually functioned as organelles. The membranes of organelles such as mitochondria and chloroplasts are similar to bacterial cell membranes, and mitochondria even have their own genome that replicates independently of the larger cell’s chromosomes.
I even found a modern, clinical consequence of this theory, a diagram of which is posted on my fridge because it was so fascinating: researchers were wondering why crush injuries were often so severe and why the response to the injury is often worse than the trauma itself. They did some experiment (I can’t remember the design) where they found out that the mitochondria were triggering a host immune response from the mouse’s cells. It was as if the mouse’s cells were attacking an invader which had actually invaded two or three billion years previously. Essentially their defenses were raised by the prokaryotic components of their own cells. All very interesting.
For me bacterial endosymbiosis was my first Big Idea in the study of life, which I loved. Coincidentally, I remember (and will always remember) Carl Sagan describing his first Big Idea in astronomy as a boy: it was when he found out in a book that the Sun was actually just a nearby star, and the stars were just distant suns. Well, Lynn Margulis was married to Carl Sagan and had a kid with him. Funny coincidence.
As I glance at her Wikipedia page I find that she is apparently linked to some zany ideas that had alienated her from some of her colleagues, which is a common pattern in famous scientists. Also she is apparently not the first scientist to theorize about complex cells arising from symbioses between simpler cells, just the first to detail the theory and provide microscopical evidence of it.
pseudoisaac 