Actually, I was a Bio-Anthro Major and found out it was better not to put any of the classes, which maybe should be included in BCPM, as BCPM because they can send back the AMCAS and make you change the designations. This takes valuable time and energy and could screw you later in the process. That is what my pre-med advisor told me and it all worked out for the best. Just my $0.02. Good Luck.
I also had a few courses that I had questions about. To classify your course, you should first look for it in the "Course Classification" list in the AMCAS instruction book (page 66).
If your class isn't there, you can also call (202) 828-0600 and talk to someone at the AAMC for advice. When I called, they told me to analyze the curriculum and see whether it was mostly biology (or chem or whatever) or mostly another subject. They said that I could mark it BCPM if I want, but I would have to be able to produce a curriculum and justify my decision if a med school I apply to challenges my choice.
However, keep in mind if your class IS on their list and you classify it differently, they could easily change the classification when they check your app for errors, which is time-consuming as someone said earlier.
As a general rule, if you have to post a message asking if a particular course is a science course, it probably is not. Science courses are pretty clear when you sign up for them, attend them, etc. In most colleges, if a course is (for example) ANT 323, it is an ANTHROPOLOGY course. Even though you cover topics relating to English, History, and Biology. It certainly wouldn't make the course anymore a History course than it would a Biology course.
Further, BIO 421 - Human Genetics would not count as a Social Anthropology course even if you discussed how genetics influenced social displacement of humans.