In Tuesday's Science Times, Carl Zimmer grants us access to scientists who are asking the question, "If it's so great to be smart, why have most animals remained dumb?" Researchers hypothesize that any animal with a nervous system can learn, but in the case of the test subjects—good old Drosophila melanogaster—the fast-learning fruit flies (the smarter ones) live on average 15 percent shorter lives than their unschooled counterparts.

In his brief response to the story, author and New York Times editorial board member, Verlyn Klinkenborg, reframes the question behind the research by asking whether there is "an adaptive value to limited intelligence."

Being smart, it turns out, is often high-priced: "It takes more upkeep, burns more fuel and is slow off the starting line because it depends on learning—a gradual process—instead of instinct. Plenty of other species are able to learn, and one of the things they’ve apparently learned is when to stop."

At last, perhaps, evolutionary biology explains the age old adage, "Ignorance is bliss."