There is no such thing as recreational drug use. Alan I. Leshner More Quotes by Alan I. Leshner More Quotes From Alan I. Leshner Evolution is an organizing principle and when we call it a theory, we mean it's a theory, we don't mean that it's a belief that someone holds. Alan I. Leshner principles belief mean Evolution is far more than a belief or an educated guess about how people came to be as they are. It is, in fact, the product of converging evidence from many, many different fields of science. Many, many thousands of studies that, in fact, have provided a theory, an organizing principal in fact, that describes how humans came to be. Alan I. Leshner fields facts people
