In relation to the chimp expert's remark that it was inconceivable to him that one chimp would help another carry a log, Haidt brings in the mental ability of shared intentionality, which he says is undeveloped in all animals except humans and accounted for our ability to divide labor to get things done. We needed an ability to represent mentally the intention that another human had in order to join him in any shared effort. Language is sometimes thought to be the watershed event in human cooperation, but language is after all an agreement that a combination of sounds will represent some object or action, so it couldn't have gotten off the ground without shared intentionality.
Haidt had previously talked about a "shared defensible nest" as the key prerequisite for group selection. He spins a great passage off this idea:
We might see somewhere here an idea similar to the theory of memes. I find Haidt's formulation more comprehensive and satisfying, though.If the key to group selection is a shared defensible nest, then shared intentionality allowed humans to construct nests that were vast and ornate yet weightless and portable. Bees construct hives out of wax and wood fibers, which they then fight, kill and die to defend. Humans construct moral communities out of shared norms, institutions, and gods that, even in the twenty-first century, they fight, kill, and die to defend.
There is a process known as self-domestication that accounts for the way the early human groups slowly changed to more socially cohesive units by selecting
Although we usually talk about tribalism as a negative, Haidt sees it as the essential ingredient in our social natures.friends and partners based on their ability to live within the tribe's moral matrix. In fact, our brains, bodies, and behavior show many of the same signs of domestication that are found in our domestic animals: smaller teeth, smaller body, reduced aggressiveness, and greater playfulness, carried on even into adulthood. the reason is that domestication generally takes traits that disappear at the end of childhood and keeps them turned on for life
It may sound depressing to think that our righteous minds are basically tribal minds, but consider the alternative. Our tribal minds make it easy to divide us, but without our long period of tribal living there'd be nothing to divide in the first place. There'd be only small families of foragers--not nearly as sociable as today's hunter-gatherers--eking out a living and losing most of their members to starvation during every prolonged drought. The coevolution of tribal minds and tribal cultures didn't just prepare us for war; it prepared us for more peaceful coexistence within our groups, and, in modern times, for cooperation on a vast scale as well.