Nothing. No one thing. There is no meaning. Squirrel, fish, microbes...no pondering about the meaning of life occurring there. Gibbon or gorilla: maybe some mind activity going on about life's meaning. These beings exist with little/no reflection on meaning. My personal meaning is there is no meaning, no meaningful job, no God, no reason to exist other than that we do. Yet I remain realistically optimistic or optimistically (optimystically) real about all that life encompasses.