This year?s Keystone meeting on stem cells -- surrounded by the dreamy mountains of Whistler, British Columbia -- started not with science, but with ethics. Specifically, the ethics of embryonic stem cell research, and what the scientists who study them need to remember.

Anne McLaren of the Wellcome Trust/Cancer Research UK Gordon Institute, Cambridge University, provided a basic overview of all of the ethical aspects to the work?a talk that lasted close to an hour. Some highlights: The "dishonesty" of unduly raising patients? hopes about the benefits of stem cells, whether it?s more or less ethical to create embryos versus using donated embryos, and research that has ethical impacts on society. A fascinating example of the latter: Creating gametes from pluripotent stem cells, perhaps enabling same sex couples to have a baby that is genetically from both parents, or a single parent to provide both egg and sperm. ("I would fine that a little difficult, but will my great-grandchildren?" she asked.)

Her conclusion? That stem cell scientists are not ethicists, but they have more knowledge about stem cell science, and therefore a duty to explain what they are doing to the general public.

McLaren told me after the talk that the meeting organizers asked her to start the meeting off by discussing the ethics of stem cell science. The remainder of the meeting is all science, she noted, and the ethical considerations provide an important backdrop for everything else to follow. It?s embryonic stem cell scientists? "responsibility to society" to always consider the ethical side of what they?re doing, she said.