Not sure whether the expansion of this 'psychological debt model' is desirable. Because it's impossible to quantify such debts without money, it becomes more difficult to optimize allocation. Maybe the people in the woods haven't found water during many days. Suppose I have some water. More than I'd need for now, but not enough to last for years. I would not be inclined to give any to them. Sure, the woods people might make me a meal or sing for me which is nice, but my water supply is ultimately a guarantee for my long term survival. But if they did have even the concept of money, they might offer a high price, a price that allows me to say 'hey, with these resources i could build a house/attract a partner/drive away in a lambo and that's more useful to me than one month out of my seven months of water'. The antropologies make a compelling case for a different precursor to money and these gift economies are very similar to a money based economy. But money does offer the additional benefit of value quantification and security of deposits.