6. Explain the process of natural selection and why it is considered a "blind" process.

The following is a synopsis of Darwin's formulation of the theory of evolution by the process of natural selection:

Darwin assumed that organisms naturally vary in almost every attribute that they display.

Such variation might lead to differences in survival or reproduction.

Because an excess number of progeny are produced in all organisms, there is a competition amongst them to produce successful progeny, or what Darwin called a "struggle for existence."

If the variation that leads to differences in survival or reproduction is heritable, then those individuals that produce the most progeny will also tend to have offspring that resemble the parents, and the species will evolve by a process that Darwin referred to as natural selection.

New species arise from old species by the acquisition of slow changes in traits, behavioral traits included, and such changes are driven by the blind force of natural selection.

Evolution by natural selection is really blind. At its core, the process of natural selection is stochastic or governed by the laws of chance. Individuals die and survive and reproduce as a function of their traits, but it is a probabilistic outcome. Moreover, the ultimate source of all genetic variation, the raw material for natural selection, is the process of mutation. Mutations arise in a probabilistic fashion. Sometimes the mutations are beneficial, but, more often than not the mutations are detrimental and such detrimental mutations are weeded out by natural selection. Natural selection tends to sift out those beneficial mutations that tend to arise only rarely in a population, and eliminate detrimental mutations.