Making Manimals

If you've been laughing at those Neanderthal presidential candidates who still don't believe in evolution, it's time to sober up. Every serious scientist knows we evolved from animals. The question now is whether to put our DNA and theirs back together.

We've been transplanting baboon hearts, pig valves and other animal parts into people for decades. We've derived stem cells by inserting human genomes into rabbit eggs. We've created mice that have human prostate glands. We've made sheep that have half-human livers. Last week, Britain's Academy of Medical Sciences reported that scientists have created "thousands of examples of transgenic animals" carrying human DNA. According to the report, "the introduction of human gene sequences into mouse cells in vitro is a technique now practiced in virtually every biomedical research institution across the world."

Why have we done this? To save lives. If you can't get a human heart valve, a pig valve will do. If you can't get human eggs to clone embryos for stem cell research, rabbit eggs will do. If you can't use people as guinea pigs in gruesome...