Sometimes. I think some of the most amazing discoveries are made when people from different science backgrounds work together. Scientists become specialists in a very small area, but there is nothing to stop people looking at something in a different area of science. Of course it is easier to move into a different area of science if you work with someone who already knows a lot about that area.
Definitely! In fact I’ve recently moved fields from Psychology to Epidemiology to answer my PhD question. I think it’s really important to look to other areas for ideas, and some of the most interesting science ideas can come from 2 people with very different scientific outlooks coming together and working together.
I’ve never felt like doing that myself yet, but scientists do do it quite a lot. For example, the person who taught me when I was at University in America started off studying anthropology (the study of people, culture and how communities are formed), and realised that what interested her most about that was the languages spoken by the people she studied, so she became a linguist instead!