These foods included, predictably, cultivated foods such as bread (made from grain), rice, and potatoes. Zuk couldn’t resist asking a question, namely why the inability to digest so many common foods would persist in the population, observing, “Surely it would have been selected out of the population.” Cordain’s response? That humans had not had time to adapt to these foods, to which Zuk retorted, “Plenty of time.” Apparently, in her book, Zuk produces numerous examples of evolution in humans occurring in a time frame of less than 10,000 years, including: