It has no relationship to what used to be called linguistics. You can regard behavior as the topic of inquiry and you're trying to get an organized account of it. Or you can regard behavior as just data. There's a crucial difference between data and evidence. Data is just phenomena around you.
Evidence is a relational notion.
Something is evidence for something else. The second approach would say that data, or behavior, is interesting in so far as it is evidence for theoretical understanding. For me, the topic of inquiry is not the noises that you and I are making. That's just a way of helping us get to the topic of inquiry and learn something about it. Now, if the data of our interactions help you find out about that, good.