Cuvier's Anatomical Rules 1. As it is not in human record, but in natural history, that we are to look for the means of ascertaining what has already been, it is here proposed to which have been transacted in time past. Resemblance between insular inhabitants and those of the nearest continental mainland 4. Differences, and yet relationships, between the inhabitants of the various islands in the Galapagos Archipelago 5. Sexual selection and reproduction as a means to 'passing on' a favorable variant, i.e., the promotion of adaption.
Heritable variations are fortuitous, viz., at random, by chance.
The development of organisms is basically non-teleological, viz., no apparent purpose, design, or direction is implied. Species cannot be considered to have reached a state of 'perfection' - the very possibility of improvement, in the sense of better adaptability, is evolution. The potential reproduction rate of organisms is higher than the increase rate of the food supply, the Mathusian population pressure. The number of individuals within a species remains fairly constant. Individuals within a species are not identical but show variation.