Is there a purpose to life?

There are lots of interesting snippets in Bill Bryson's A Short History of Nearly Everything. For example, a lichen grows very very slowly and it seems the only purpose of its life is to just keep on living. As for human beings, the whole history of our existence is very very short, compared, e.g., to the history of the Earth. If I should stretch my arms to their fullest extent and imagine that width as the entire history of the Earth, in a single stroke with a nail file I can eradicate human history. It seems so insignificant!

Yet most of us human beings feel, or believe, that there must be a purpose to life, at least to "my" life, if not the lichen's. We refuse to accept that our lives are purely a matter of chance, that there is no long lasting purpose or meaning to it. We find it hard to believe that we would exist for no particular purpose. Some people commit suicide when they cannot find the purpose of their lives; other keep on searching. Most people feel lost if they do not know the purpose of their lives. It is a cruel world indeed if we are compelled to spend our lives looking for a purpose, while there is none to be found.