How can something as simple as a fly prove the Sunnah without a shadow of a doubt?

There's nothing much to prove because modern science is already beginning to agree with such things where as islam discovered things century's back.. Not only facts about the fly but sunnah also tells us to lick the tips of the fingers after eating.. modern science proved that there are chemicals there that help digestion. Only people who want to believe and listen will understand. This is the beauty of Islam. There's an answer for all problems and proof of why we do things in such a manner. No other religion is as strong as islam.. every other religion has been changed and altered in many ways. But islam is one that has been the same for years.