Change in the properties of groups of organisms over the course of generations
Groups of organisms undergo descent with modification. may become subdivided so are derived from a common ancestral population.
before Darwin. Believed that variation is accidental imperfection. Each species has been created individually by God. (special creation)
classified plants and animals hoping to discover the pattern of the creation
same processes operated in the past as in the present, and that the observations of geology should therefore be explained by causes that we can now observe.
proposed that each species originated individually by spontaneous generation from non living matter, starting at the bottom of the chain of being. Species originated at different times so we now see a hierarchy of species because they differ in age.