This is a question geared toward human evolution, but I figured a biologist would be able to answer it. There are two parts: 1. If supposedly, we physically evolved (less hair, stand up straight, etc.) because we changed our behaviour, would it be safe to say that generally, as something mentally evolves, it physically evolves? Does intelligence cause physical evolution? (of course over a long period of time). 2. Furthermore, if this is true, could it be possible for humans to physically de-evolve back into more ape-like animals if for some reason we mentally became more ape-like (for example, if all forms of communication and education were somehow lost)? As is obvious I am not an expert in any respect, just curious. Thanks!