Comment by asdfman123

It's like letting a cat sniff your hand or get used to your presence. We're smelling each other out at a subconscious level.

And more concretely, you're determining someone's values before offending them. Through small talk you might discover they're more conservative. Maybe they're hippies at heart. Maybe they hate dark humor, maybe they love it.

If you know those things, you can choose which serious conversations you'd like to have and which you'd better avoid. Plus the process of sniffing each other out means there's more baseline trust going in.