Viewing the 17,000-year-old cave paintings of our Cro-Magnon ancestors in Lascaux, France yesterday, I wondered what they would think of their more developed descendants. Suddenly, I thought I heard a Cro-Magnon chorus echoing through the caves:

“Vous pensez que vous êtes supérieur. Vous êtes très stupide. Votre intelligence et le comportement insultent vos ancêtres Cro-Magnon. On n’a jamais changé le climat!”

• Gordon C. Stewart, Beynace et Cazenac, France, June 15, 2016