How does social science work with other cultures?

The social sciences have a great deal of interest in different cultures: in fact, most fields in the social sciences (anthropology, psychology, etc) have a discipline called "cross-cultural studies" that looks at similarities and differences across cultures. 
Many studies in the social sciences today make a point of exploring hypotheses across cultures. Psychology, for example, has historically conducted studies and experiments using mostly educated, wealthy participants from Western countries. However, more recently, the field has made a big effort to include people of all ethnicities and from many different countries in their findings (although there are still a large number of studies conducted only on psychology undergraduates!). 
This work is very important because we need to find out whether our findings DO actually apply to people from many cultures, or whether our findings only apply to certain groups of people. In this way, the field of social sciences can help uncover truths and knowledge about people from many cultures. For example, a great deal of very interesting linguistic studies have been done with the Pirahã people of the Amazon basin. Their language is extraordinarily unique and has challenged many assumptions linguists previously had about the nature of all languages.