CharlesDarwin? was the father of evolutionary biology. See also Evolution.

I believe you'll find the Darwin being referred to in relation to MacOSX (pronounced "Mackoss Ten" or something like that).

Darwin is the "base OS" that includes the Mach micro-Kernel and a (mostly FreeBSD-derived) UserSpace. Hence the claim that MacOSX is "Unix". On top of this sits all the OSX graphics environment (Aqua) and the programming APIs Cocoa and the older Carbon. These APIs don't really use the unix way of doing things - for example, OSX has its own "!NetInfo?" service for resolving things instead of using /etc/passwd or /etc/hosts.