Social behaviour is determined by reproductive success

In The selfish gene, Richard Dawkins explains human social behaviour in terms of reproductive success. For example, women are more faithful than men, because unfaithful men can reproduce more easily than unfaithful women, under the assumption that women put more effort in raising the kids.

Dawkins assumes that genes are crucial in this process: faithfulness is supposed to be a genetic trait. This may be justified in some cases, but blind application smacks of Lamarckianism.

There is considerable evidence to suggest that Dawkins' example is an instance of self-delusion. It may be adaptive for women to appear more "faithful" than men, but what is chiefly adaptive is to find at least one man (and that usually means only one man) who is willing to carry some of the burden of protecting, feeding and sheltering children.

Evidence from closely related primates has shown that a fairly high percentage of offspring among species that tend to practice pair bonding behavior similar to that seen in humans are not the biological offspring of the pair-bonded male.

Perhaps the male derives other benefits from pair-bonding, aside from simple reproductive success? Perhaps being a pair-bonded male with offspring signals to a larger number of females little more than that this is a reproductively competent male (not only that, but they can look at the children and decide whether the traits they suspect he has passed on to them are traits they desire in some of their own offspring?)

Reproductive success is almost incontestably a significant factor in shaping human behavior, at least in the aggregate. But accepting this notion doesn't necessarily have to lead to the first or most naive set of conclusions.