From Wikipedia:
Mismatch theory is a concept in evolutionary biology that refers to fluidity in fitness criteria.The essence of mismatch theory is that organisms possess traits (including behavioral, emotional, and biological) that have been passed down through generations, preserved by natural selectionbecause of their adaptive function in a given environment. However, the given environment of the evolutionary period can be quite unlike the current environment. Therefore, traits that were at one time adaptive in a certain environment, are now "mismatched" to the environment that the trait is currently present in. This can present a number of problems for the organism in question.
I think Delta as a whole might be "mismatched"; I think Deltas are better suited for hunter-gatherer, gift-based societies