An anonymous reader writes: The U.S. general population is often the butt of jokes with regard to their understanding of science. A survey by the Associated Press now shows just how arbitrary and erratic the public's dissent can be. 'The good news is that more than 80 percent of those surveyed are strongly confident that smoking causes cancer; only four percent doubt it. Roughly 70 percent accepted that we have a genome and that mental illness is seated in the brain; about 20 percent were uncertain on these subjects, and the doubters were few. But things go downhill from there. Only about half of the people accepted that vaccines are safe and effective, with 15 percent doubting. And that's one of the controversial topics where the public did well. As for humanity's role in climate change, 33 percent accepted, 28 percent were unsure, and 37 percent fell in the doubter category. For a 4.5-billion-year-old Earth and a 13.8-billion-year-old Big Bang, acceptance was below 30 percent. Fully half of the public doubted the Big Bang (PDF).'