1.Until recently (in terms of the evolution of our species), our ancestors tended to go to sleep when the sun set and wake up when it rose. Once our ancestors learned how to control fire, they undoubtedly stayed up somewhat later, sitting in front of a fire. But it was only with the development of cheap, effective lighting that many members of our species adopted the habit of staying up late and waking several hours after sunrise. Considering that our biological clock and the neural mechanisms it controls evolved long ago, do you think the changes in our daily rhythms impair any of our physical and intellectual abilities?