Evolution of cooperation through cumulative reciprocity
phys.org
Understanding reciprocal cooperation is a key element to understanding how people work together. Whether it is friends who exchange favors, animals who exchange food or services, or nations that coordinate their policies, all are essentially reciprocal interactions.

“The fact that humans sometimes make errors when they interact with others can be detrimental to cooperation. As such, any model that wishes to approximate human behavior closely must take that into account.”