Natural selection almost always builds on what went before.... It is the resulting complexity that makes biological organisms so hard to unscramble. The basic laws of physics can usually be expressed in simple mathematical form, and they are probably the same throughout the universe. The laws of biology, by contrast, are often only broad generalizations, since they describe rather elaborate (chemical) mechanisms that natural selection has evolved over millions of years.... I myself knew very little biology, except in a rather general way, till I was over thirty...my first degree was in physics. It took me a little time to adjust to the rather different way of thinking necessary in biology. It was almost as if one had to be born again. By