ALTHOUGH AMERICAN SCIENTISTS have made major contributions in stem cell research, progress has been limited by political decisions which have their basis in religious and ethical concerns rather than scientific considerations. Stem cell research is not prohibited in the United States, but restrictions on federal funding (which is the major source of funding for scientific research in this country) mean that less research is conducted in this area than would be expected if such restrictions were removed. Because of the political and religious basis of the restrictions, they could be changed at any time. In addition, recent scientific advances may make the major issues of the stem cell research controversy moot: for example in November 2007 by Shinya Yamanaka and James Thomson, working independently, both ...