I saw a theory on one of the health letters that stated that the various things that can go in our circulatory system that blood veins and arteries can punture because of different thing circulating thru us and that the body sends the so called bad cholestrol (ldl) to the rupture to patch it up. They equated this to an alien ending up on earth and come upon a train wreck with lot's of ambulances there with their flashing lights and sirens etc. the aliens would conclude that ambulances caused train wrecks

I didn't state that near as well as the original publication but I hope you got my point