I guess that is one thing to think about. This is a correlational study which means we can't say that these age preferences are an evolutionary strategy. However, they picked children from different households and asked them separately, therefore cutting down on learned strategies with respect to the entire study. Maybe doing this study in another culture is an idea.

I don't think the purpose of this study was to make people feel abnormal that do not think along this line. In evolution there are always exceptions and that is what makes evolution so interesting and hard to follow. These exceptions allow for variation and selection.

I think that since this is an evolutionary theory it would have supplemented the findings if the authors had included previous findings of how the age of chimpanzee's affects who they look for or mate with. If this research has not been done then the authors could have mentioned that this research could supplement their research.