The controversy over the use of primates in research admits of no easy answers. We have all benefited from the medical discoveries of primate research--vaccines for polio, rubella, and hepatitis B are just a few. But we have also learned more in recent years about how intelligent apes and monkeys really are: they can speak to us with sign language, they can even play video games (and are as obsessed with the games as any human teenager). And activists...