The Unbearable Lightness of Evolution
It is rare that I read a book and find myself mumbling under my breath in anger, but such was my response to reading Simon Morris’ Life’s Solution: Inevitable Humans in a Lonely Universe. The central thesis of the book is that life was unlikely to have evolved on planets other than earth, but that here the evolution of us, or something like us, was very likely.
Morris begins his argument by accepting the standard Drake equation (here simplified somewhat- see this site for the full equation), that the number of planets with life on them somewhere in the galaxy, Nl, is a estimate by the product of the total number of planets, Np, and the proportion of the planets that are habitable, Fl: Nl=Np Fl. Now, many things have to occur for a planet to be habitable (it has to have the right distance from a star, has to be neither too big nor too small, etc.), and Morris rightly argues that Fl is very small. From this, without quantifying how small Fl is or how big Np is, he leaps to the conclusion that the most likely value of Nl is 1- that is, there’s just Earth!
Morris then moves to the process of organic evolution under natural selection, and cogently describes the process as a path of evolution occurring through a space of possible evolutionary trajectories. The author stress how convergences in traits during natural selection, like the repeated emergence of binocular vision, imply that this “space” may be smaller than previously thought. From this sensible observation, he leaps to the conclusion that this “space” is so bounded that intelligent life is bound to develop, and indeed is destined to look a lot like us humans- binocular camera eyes, big head, probably bipedal, the whole shebang!
As a scientific work, the book is lacking, for its series of fascinating anecdotes do not justify its grand conclusions. However, as a philosophical piece it is fascinating. Morris’ central goal is to reinsert teleology into the universe. Ultimately, he wants to feel that the existence of humanity is not just a cosmic accident, a contingency, but has some sort of inevitability to it. In contrast, I find the contemplation of the contingent nature of the universe somewhat bracing and invigorating By personality, I am closer to the late Stephen Gould, who continually stressed that if one ran back the clock of life and reran evolution, things would turn out very different. As the scientific evidence isn’t adequate to separate out which viewpoint is accurate, the issue becomes a Rorschach test. For some people, as Milan Kundera once said, enjoy viewing life thus: Es muss sein! For others, life could just as well be otherwise (Es konnte auch anders sein).
