Thank you for the clarification, Evo. I certainly did not mean to suggest that any significant changes to the gene pool can occur in one generation. Most changes to species or traits occur over very many generations (for example, in the Lenski long-term evolution experiment
, the ability to metabolize citrate evolved after 31,500 generations).
Although 30-35 years may be the current human generation time, generation times were almost certainly shorter than that throughout most of human evolution.