In the past few months, animal-rights groups have stepped up their demonstrations against academic researchers who use animals, spawning a new wave of concern among scientists. In February, extremists caused a fire at the home of a researcher from the University of California at Los Angeles, and protesters struck the husband of a scientist from…

It seems hard to believe that Dolly the cloned sheep was born 10 years ago, kindling furious arguments over the prospects and ethics of cloning a human. Today, the controversy over cloning is entwined, often confused, with concerns over the use of human embryonic stem cells. Most people are unclear what cloning is, and they know even less when it…