Bad Evolutionary Arguments

The introductory psychology course I teach for is very heavy on evolutionary psychology. The danger with evolutionary explanations is that it's pretty easy to come up with bad ones. Here's the best illustration I've seen, from Saturday Morning Breakfast Cereal:

How do you tell a good evolutionary argument from a bad one? It's hard to test them with experiments, but that doesn't mean you can't get data. Nice supporting evidence would be finding another species that does the same thing. This hypothesis makes the clear -- and almost certainly false -- prediction that people are likely to adopt babies that fly in out of the blue. You would want to show that whatever reproductive advantage comes from having your genes spread widely (adopted children themselves have more children?) is not overwhelmed by the disadvantages of not being raised by your biological parents (there is data showing that, all else equal, step-parents invest lest in step-children than biological parents invest in their biological children. I expect this generalizes to adoptive parents, but I'm not sure; it might be confounded in modern day by the rigorous screening of adoptive parents).

Etc. We try to teach our students to critically evaluate evolutionary hypotheses. Hopefully it has taken.