Cro-Magnon man, who carved out a primitive existence in Europe 20,000 years ago, would likely have been stumped by a Sudoko puzzle, but he had a bigger brain than you. In findings that defy conventional wisdom, paleontologists say the human brain has shrunk by about 10 percent over the last 200 centuries, losing a portion of brain mass "roughly equivalent to a tennis ball in size," says Kathleen McAuliffe in Discover. Does this mean human beings are getting dumber, or are smaller brains not necessarily bad?

Face it. We're becoming stupid: This makes sense, say the editors of The Economic Times. It took considerable wits to survive the perils of Upper Paleolithic life, but we no longer need to be smart to stay alive. So our heads have stopped evolving into ever larger melons, and we have the luxury of becoming "steadily more stupid."
"Shrinking brains are making humans dumber"

A smaller brain is not a disadvantage: "When it comes to brain size, bigger doesn't always mean better," say the editors of NPR. Duke University anthropologist Brian Hare says "the decrease in brain size is actually an evolutionary advantage," because it could indicate we're evolving into a less aggressive animal. Though common chimpanzees, for instance, have bigger brains than bonobos (or dwarf chimps), they're less likely to resolve issues through teamwork because they're more aggressive.
"Our brains are shrinking. Are we getting dumber?"

The planet still has plenty of smart people: "Even if the median human intelligence is decreasing," says Razib Khan in Discover, we'll do just fine. There are far more people on the planet than ever before, so, in raw numbers, our generation has more "very bright people" than any previous one. "If the stability of civilization rests not on the median human, but the coordination and mobilization of large numbers of cognitively gifted humans, then perhaps we should not worry too much" about the loss of a little gray matter.
"Slouching toward idiocracy?"