I once worked for a ~10 person consulting firm. We had a contract to do some IT work for a large firm's HR department. We'd joke that the HR department needed i

I once worked for a ~10 person consulting firm. We had a contract to do some IT work for a large firm's HR department. We'd joke that the HR department needed its own HR department, to work out the politics among them. And, we'd joke that we needed clients so we could borrow their office politics so we could have some. My pop-science (I learned about Dunbar's number from Malcom Gladwell's 'Tipping Point') theory for this is that we're wired to think of some small set of people (~150) as 'our group'/'my people', and that within that group we're more likely to forgive, and outside that group, we're more likely to blame.