Creationist critics often charge that evolution cannot be tested, and therefore cannot be viewed as a properly scientific subject at all. This claim is rhetorical nonsense.

Facts do not 'speak for themselves'; they are read in the light of theory.

All evolutionary biologists know that variation itself is nature's only irreducible essence... I had to place myself amidst the variation.

Life shows no trend to complexity in the usual sense-only an asymmetrical expansion of diversity around a starting point constrained to be simple.

Some beliefs may be subject to such instant, brutal and unambiguous rejection. For example: no left-coiling periwinkle has ever been found among millions of snails examined. If I happen to find one during my walk on Nobska beach tomorrow morning, a century of well nurtured negative evidence will collapse in an instant.

Precise adaptation, with each part finely honed to perform a definite function in an optimal way, can only lead to blind alleys, dead ends, and extinction.

Theory and fact are equally strong and utterly interdependent; one has no meaning without the other. We need theory to organize and interpret facts, even to know what we can or might observe. And we need facts to validate theories and give them substance.