Aristotle is often characterized, by both philosophers and evolutionary biologists, as the fountainhead of a typological theory of species that is absolutely inconsistent with evolutionary thinking. D'Arcy Thompson, on the other hand, in his remarkable On Growth and Form, claimed that the idea of using quantitative methods to help understand morphological relationships among animals of different species took root in his mind during his work on Aristotle's biology:

A theory that asserts that species of a genus differ only in the relative magnitudes of their structures sounds very different, and might be thought to be incompatible with, a theory that claims that there are complete discontinuities between one eidos and all others. Can Aristotle consistently have held both these views? He can, and he did. To understand how he did so, one must understand the way in which he used the Academic technical notion of ‘the more and the less’ in his biology.