What makes us a new kind of animal, and so different and successful as a species, is we rely heavily on social learning, to the point where socially acquired information is effectively a second line of inheritance, the first being our genes. Imagine something like a cyclical drought. You may have never experienced one, so you have no idea how to survive in one, and maybe even your parents haven’t, but say Grandma remembers that when she was a child, a drought came and everyone went to the mountain, past the forest, and they discovered water. So, she guides them to safety. These kinds of stories exist in the anthropological record.
That gets you to social learning, but dual-inheritance theory goes a little further and says, actually, that inheritance is itself an evolutionary system. It has variation. When people socially learn from each other, they often learn without understanding why what they’re copying—the beliefs and behaviors and technologies and know-how—works. People tend to home in on who seems to be the smartest or most successful person around, as well as what everybody seems to be doing—the majority of people have something worth learning. When you repeat this process over time, you can get, around the world, cultural packages—beliefs or behaviors or technology or other solutions—that are adapted to the local conditions. People have different psychologies, effectively. We almost speciated around cultural lines.
— Read on m.nautil.us/issue/81/maps/the-cultural-distances-between-us