There's an excellent essay on Anarchy Unbound about this. It analyses inter-group transactions and methods to not be cheated. Essentially, cheaters are defined as people who discount future transactions as 0. Therefore, I've easy to filter them out it's to require an upfront cost for any unknown person to transaction with you.
The thing that blew my mind was you can use non-monitary costs. E.g. if someone from an out group learns your language and your culture, that's a moderate investment. To recoup that, they need to make multiple transactions and are therefore less likely to cheat.
It's by no means a perfect metric - and it works much better in smaller, tribal settings - but it's still a fascinating analysis
The thing that blew my mind was you can use non-monitary costs. E.g. if someone from an out group learns your language and your culture, that's a moderate investment. To recoup that, they need to make multiple transactions and are therefore less likely to cheat.
It's by no means a perfect metric - and it works much better in smaller, tribal settings - but it's still a fascinating analysis