How to be rational about ethics
http://www.arn.org/blogs/index.php/literature/2008/04/11/how_to_be_rational_about_ethics
4/11/2008
"From an evolutionary perspective, we humans have good reason to
be wary of things that seem to be 'unnatural'. Anything out of the
ordinary can be dangerous. But the evolutionary origin of that
response also guarantees that it will be guided more by emotion than
by reason."