> Viruses are the enigma of evolution. Are they just chemicals, or living? Biology is full of edge cases like this. For a few more examples, google "species pr

> Viruses are the enigma of evolution. Are they just chemicals, or living? Biology is full of edge cases like this. For a few more examples, google "species problem". Human beings often like to classify things into discrete groups, but that doesn't necessarily map onto the natural world all that well.