This doesn't even necessarily require "wiring". A group that behaves in a way that ensures its continued existence will continue to exist. A group that doesn't won't. Larger time scales favor a stronger focus on group survival at the expense of any other actual purpose.
A group that actively recruits, actively protects itself from threats, and actively reinforces in-group dynamics can outlast one that doesn't do those things. Few people will join a group that exists only manifestly for the purpose of perpetuating the group, though...
...so "fitness" in an evolutionary sense for a group depends on having ostensible purposes that make it attractive. For a young and growing group, being attractive to outsiders is more important than long-term survival.
But at the point where a group is well-established enough that people are being born and raised in it, the calculus changes.
Some people are studying these dynamics very carefully when they create a group (L. Ron Hubbard was very deliberate in how he crafted Scientology) and some people are just doing what works and some luck into the magic formula for group growth and survival.
And since we're talking about group dynamics, in any given group there will be some people acting more organically than others.
But however they get there, a group whose behavior reinforces the group will tend to outlast one that does not.
But however they get there, a group whose behavior reinforces the group will tend to outlast one that does not.
It's not that nobody anywhere in the hierarchy of the Cathlic Church, for example, believes in a higher mission for the church than survival... but at the group level, nothing will ever come before survival of the group. Centuries of social evolution have brought them there.
