"Fact" is commonly used to refer to the observable changes in organisms' traits over generations while the word "theory" is reserved for the mechanisms that cause these changes: Writing in 1930, biologist Julian Huxley entitled the third book of the wide-ranging series The Science of Life, which dealt with the fossil record and the evidence of plant and animal structures, The Incontrovertible Fact of Evolution.
O termo "feito" úsase comunmente para referirse aos cambios observables nos trazos dos organismos co paso das xeracións, mentres que a palabra "teoría" resérvase para os mecanismos que causan estes cambios: En escritos de 1930, o biólogo Julian Huxley titulou o terceiro libro da ambiciosa serie The Science of Life (A ciencia da vida), que trataba do rexistro fósil e as evidencias de estruturas de plantas e animais, The Incontrovertible Fact of Evolution (O feito incontrovertible da evolución).