1. A gradual process in which something changes into a different and usually more complex or better form. See Synonyms at development.
a. The process of developing.
b. Gradual development.
a. Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
b. The historical development of a related group of organisms; phylogeny.
I do, however, respect your opinion.
I think gradual is the key word here.
Marylin, we are discussing science here so I thought I would use a scientific definition and skip all the other ones that do not apply to biology. I used a definition which simplified it a bit. Let's see the "Biology" one you skipped.
"change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift." -dictionary.com via Random House
Essentially, the genes change over generations as genes which favor an organism to survive to reproduce are carried on. As seen with the hunters and the deers as the small racks are selected.