  The evolution of cooperation has remained an important problem in
evolutionary theory and social sciences. In this regard, a curious question is
why consistent cooperative and defective personalities exist and if they serve
a role in the evolution of cooperation? To shed light on these questions, here,
I consider a population of individuals who possibly play two consecutive rounds
of public goods game, with different enhancement factors. Importantly,
individuals have independent strategies in the two rounds. However, their
strategy in the first round affects the game they play in the second round. I
consider two different scenarios where either only first-round cooperators play
a second public goods game, or both first-round cooperators and first-round
defectors play a second public goods game, but in different groups. The first
scenario can be considered a reward dilemma, and the second can be considered
an assortative public goods game but with independent strategies of the
individuals in the two rounds. Both models show cooperators can survive either
in a fixed point or through different periodic orbits. Interestingly, due to
the emergence of a correlation between the strategies of the individuals in the
two rounds, individuals develop consistent personalities during the evolution.
This, in turn, helps cooperation to flourish. These findings shed new light on
the evolution of cooperation and show how consistent cooperative and defective
personalities can evolve and play a positive role in solving social dilemmas.
