New research challenges the one-level view of evolution, showing natural selection works on individuals and groups together.

Introduction. Definition of natural selection ; Relationship to genetic drift and evolution ; Restricted meanings of "natural selection" ; Modes of selection ; Summary -- Philosophical comments.

Have you ever wondered why our universe is made up of something rather than nothing? It can hurt your brain if you think about it too much because if there were nothing you would have no brain—no you ...