The current state of evolutionary biology is one of a flourishing science. With recent advances in molecular biology, we are now able to pursue questions that our scientific forebearers could only speculate on. Since Gregor Mendel's papers were rediscovered in the early part of the 20th century, biologists have had the tools to follow and analyze many heritable traits. It is precisely these traits which can be accounted for in evolutionary change. Charles Darwin defined natural selection as a struggle for existence. Moreover, those individuals best suited for a particular environment will survive to give life to individuals who are similarly well suited.

This is all too simple, though. To say that individuals are selected for unique adaptive traits within a given environment is not enough. Populations of individuals is the level at which ultimate evolutionary change will be seen. This is often confusing for people. Natural selection acts upon individuals. Evolutionary change occurs in populations. This change requires many generations. This is why it is so difficult to follow during the relatively long generation span of our primate heritage. Herbert Spencer coined the phrase, "survival of the fittest." This is misleading, however. Individuals do not survive through geological time, but evolutionary lineages often do, and more accurately, what they inherit and pass on to future generations, does survive: that is, genes. Charles Darwin, in defining his theory, preferred to use the phrase, "descent with modification." (Incidentally, this theory was concurrently discovered by the naturalist Alfred Wallace.) This is all far more easily seen if we choose to study organisms with much shorter generations, such as bacteria or fruit flies. There are other suggested mechanisms for evolutionary change: genetic drift, symbiogenesis (see Lynn Margulis), founder effect, among others. Still, even amidst all of this theorizing, it is not disputed that natural selection plays a very large and important role in evolution.

It bothers me when someone asks me if I believe in evolution. What? What does belief have to do with it? I understand evolution, and I know how it has shaped our natural world. I have read much of the scientific literature on evolutionary biology, therefore its mechanisms are familiar to me. In so far as belief is defined as having confidence in a given set of scientific facts, then yes, I suppose I do believe in evolution. But in the common usage of the word belief, as something accepted upon faith, it has no place in this discussion. Evolution is as well founded as any discipline of science can be. There will continually be fervent discussion on the intricacies of the mechanisms that make evolution work, but that only serves to justify its place as a well-founded science.