Firstly there is an awareness that they are part of the same environment as their peers. Secondly they begin to comment on this environment before they begin to comment on themselves. Why is this? It is safer to talk about something they have in common with other people than to talk about themselves.
This is why small talk is so important. Small talk acts as a bridge between talking about something that you know the other person will be able to relate too. Ie: What a miserable day, I can believe all this rain. For sure you know the other person is aware of the weather.