Why Do Genes Give us Cancer?

Why hasn’t natural selection ensured that the protective versions of all the genes associated with cancer development or progression are the predominant type in the human population? The answer to this question is quite possibly a good example of the disequilibrium between our modern genetic makeup and what might have been the ideal human genetic condition throughout our history as a species.

Female reproduction is one of the traits that evolved most rapidly in humans relative to other primates. Hormonally regulated processes such as the timing and cycling of menstruation and preparation for breast feeding changed greatly a few hundred thousand years ago. This almost certainly involved selection on genes involved in hormone production over a period of thousands of generations.