I'm actually looking for the answer for a philosophical paper. Heidegger says not everything people do can be objectively justified, some practices only make sense in the context of their culture, which is basically a self enclosed jumble of practices.

An Inuit guy I worked with told me the 'eskimo kiss' comes from wanting to expose minimal skin in a cold climate, so I thought different cultural greetings would be a good example of practices that only make sense in their own cultural context!