Atheism is only a response to the proposition of a deity's existence.
Being unconvinced of a deity doesn't require other beliefs. I know atheists who believe in crystals, chi energy, spirits, etc.
In our culture, the answers for questions like why are there so many animals, or how did the universe begin are often answered by scientific fields w\o religious explanations, but that doesn't mean an atheist must accept those explanations, as my crystal friends show.