Who cares about that then?
Well, studying child development is important, whether that's physical, social, emotional, learning, thinking, and communication and language.
Are there certain aspects of child development we should not study?
Overall, the study just shows that babies have an in-group preference, as opposed to an out-group preference. This is obviously no surprise, as evolution has biologically dictated that we have an in-group preference for survival and reproduction. However, it would be a mistake to reduce people to purely biological functions.