One can thus conceive of extraversion as leading to
benefits in terms of mating opportunities and exploration of
novel aspects of the environment but carrying costs in
terms of personal survival and possibly offspring welfare.
It is unlikely that there will be a universal optimal position
on this trade-off curve. Instead, local conditions, including
the density and behavioral strategies of surrounding individuals,
could lead to a constant fluctuation in the optimal
value, and hence genetic polymorphism would be retained.