Something I’ve been thinking a lot about lately is the idea of universal common descent. I know there has been some recent questioning of common descent, but let’s pretend for a second that common descent is indeed the model — and even if it is not, the fact that life has basically come from one branch of evolution is still pretty phenominal.
My thoughts, however, have been less along the lines of “oohh everything is related to everything an intertwined and has a common history” (a la the whole “all humans descended from the same first humans so therefore everyone is good and the same”), but more about the fascinating aspect that since the first collision of proteins or whatever the made the first (or first three) cellular-type structures, that act of “life begining” has not happened again.
All life that we know of is carbon-based and somehow consists of cells and consumes energy. And that is all we know of “life.”
With the Mars Rovers treking across another planet and the new Mars Reconnaissance Orbiter equipped with even more tools for trying to find “life” on Mars, I wonder what it is we are looking for? Obviously we are looking for carbon-based lifeforms that we are familar with — a plant, bacteria, an incest, an animal, etc. But for all we know, “life” on Mars evolved very differently so as it didn’t require cells or solar energy. Maybe “life” on Mars (or anywhere else in the universe, for that matter) is invisible to our eyes and instruments or lives in a different plane or existence due to it’s different base-atomic structure.
I wonder if there is any value to considering the definition of life. Could a star be considered “alive”?
On a related note, I wonder why evolution has only allowed sentient life (as far as we know) to happen once. Does the fact that humans exist as we do create some sort of metaphysical impossability for other animals to develop language as seemingly complex as ours? Can no other animals learn to create fire?
… I apologize for the “everywhereness” of this post and its rather abstract nature, but I do wonder what “life” is and how it came to be that “life” only started on Earth once. I’m sure the chances aren’t that high of “life” randomly starting, but it seems really strange to me. What is going on?