Ruminations on the "Tree of Life"

 A few things in the first video from class for August 26 annoyed me a bit. They said for example, that "for a tree of 50 species there are more possible ways of building a tree than there are atoms in the universe". This is a problematic statement for me since my studies of astrophysics tell me we haven't figured out if the universe is infinite or not (perhaps I just haven't read the newest theory on that however). If there are infinite ways of building a tree that would change things, but to my understanding there are only so many DNA combinations you can have (an astronomical amount, but still finite). Most sources I have googled on the subject make the distinction "observable universe", and I wish this video also put in that caveat. The video also said that "the study of the tree of life typically begins with the study of the visible characteristics of the organism". I had hoped that we had progressed to the point that we no longer did this, as in my opinion we should go by the organism's genome. Convergent evolution (the process whereby organisms independently evolve similar traits) would play havoc with such a system, especially once we find extraterrestrial life. Anyone who has studied dinosaurs also knows the problems that can arise from this method, as they have been shifted quite a bit from branch to branch on the Tree of Life (we used to not consider birds dinosaurs, even though genetically they most certainly are).

This is the video by the way: