They don't replace it with artificial systems of just a few crops and domesticated animals. Instead, they use natural diversity to the full. They collect dozens of different kinds of wild roots and leaves, and hunt a wide range of animals and fish. Because their way of life doesn't demand any large scale organization, hunter-gatherer society tends to be easy on humans, too. They enjoy a good varied diet, and work much shorter hours than farmers.
Bands are egalitarian.
Hunter-gatherer religion reinforces harmony with nature. To avoid over-exploitation there are elaborate rules about which animals may be hunted and eaten, and when. All living things, and many non-living things like rivers or even stones, are believed to possess soul and demand respect, just like humans. The food crisis and the agricultural revolution. They were humans just like us.