You don't remember me...

I am not uptight about privacy because I'm hiding something. I'm uptight about it because the people who dismiss my right to privacy are dangerous to you and me and our families, personally, all the time.

Feed your friends. Feed your loved ones. Feed the people who help you. Feed your neighbors. Feed your community.

When Co-workers do things like ask about weekend plans, chat about non-work topics, eat lunch in the same room, they are--subconsciously--reaffirming that they are part of a cooperative (or, minimally, non-antagonistic) social group.

The other primates cement social bonds by grooming each other; we do it by making small talk.

If they solicit your participation in these rituals, and you repeatedly refuse those bids, you are marking yourself out as, at best, an outsider to the group, and thus potentially antagonistic.

This is all happening on the monkey-brain level; they have no idea what they're doing or how they are interpreting your response, so there's no way to clear up the misunderstanding.

To the ape sleeping in your co-worker's DNA, either you are part of the grooming circle, or you are an outsider who, for all it knows, may be coming to steal all the bananas.

at some point, either in response to an invitation, or just in the natural course of conversation, you can add in that you are a "quiet type" who "needs their silence" or what have you. customize to your personal needs. i find it helpful to imagine a well dressed elderly woman describing the sort of peace she needs to manifest.

roughly once a week if you see a group of people chatting, engage with them. keep it pleasant. it can be superficial. word will travel that you are Nice and Quiet and Not The Chatty Type protecting you from group lunches etc. if you have an office with a door that you keep closed a lot, putting up any kind of decor will also send positive signals.