Scientists debate blending of human, animal forms

November 22, 2004 | Source: Washington Post

How human must a chimera (hybrid animal) be before more stringent research rules should kick in?

During one recent meeting, scientists disagreed on such basic issues as whether it would be unethical for a human embryo to begin its development in an animal’s womb, and whether a mouse would be better or worse off with a brain made of human neurons.