Cultural evolution

Chapter 7 endnote 20, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

Just because fear appears generation after generation in your culture does not prove that fear is coded into the human genome, nor that it was sculpted by natural selection in our hominin ancestors millions of years ago on the African savanna. [...] Case in point: the Hadza of Tanzania, who have lived continuously on the African savanna for at least 150,000 years since the Pleistocene Epoch, do not recognize posed facial configurations of fear, based on my lab’s visit in 2016.

Culture evolves as its concepts — a form of social reality — change. Some scientists have argued that cultural evolution is Lamarckian, as if a static concept, once formed, is passed from person to person. I am no expert in cultural evolution, but a different explanation emerges through the lens of the theory of constructed emotion.

Let’s consider the case of a mother and baby and a single concept, “Sadness.” The mother’s brain can construct a large population of instances of “Sadness” over her lifetime: a variable pool of information about sadness. She labels certain events as “Sadness” to her baby, stimulating the baby to learn the category "Sadness" and giving him the capacity to create his own population of instances of “Sadness.” On a given occasion, what is transmitted from the mother to the child (or from any one person to another) is just a particular packet of information, not the whole concept. Each person maintains the capacity to make his or her own population, yet the concept of “Sadness” is shared. The concept is not one static representation but ever-changing; and when the concept is used, some selection takes place to construct the best instance for a given situation.

With these ideas, it should be possible to explain cultural evolution in terms of Darwinian concepts of natural selection and population thinking.  

The human species has spread into more habitats than any other species on the planet.  Between 50,000 and 60,000 years ago, our ancestors left Africa and spread through Asia, Europe, Australia, and eventually to North and South America, into the most hostile climates at extreme hot and cold temperatures.  Few genetic changes have occurred to allow our species to live in such varied environments.  The adaptations are cultural, reflecting our ability to learn from others,  combined with our capacity for conceptual combination and ability to create social reality.  We invent concepts by imposing novel functions on the physical world, including our own bodies and the physical movements of others; and then we share them with others. These functions persist only by virtue of collective intentionality. This is what allows us to live in groups and survive in negative 30 degrees Celsius for months at a time.  A single human or small group of humans with the furriest parkas and sturdiest huts would not stand a chance.  Neither would a large group of humans without the capacity for conceptual combination and social reality.  Social reality may be the basic kernel of our cultural niche, an evolving product of human brains that exist in the context of other humans brains the capacity for conceptual combination, language and collective intentionality.

Concepts are not just a social veneer on top of biology. Concepts get under your skin. If you drink a carbonated beverage, your body metabolizes it differently if you’re told it’s a diet drink.  If you’re in the southern US and  you rudely bump into someone, the person will show a larger increase in cortisol (indicating a need for glucose) and testosterone (often associated with the likelihood of aggressive behavior) than a Northerner would.  Southerners have constructed a social reality where a violation of honor evokes more violent responses of anger than in the North.  Emotions do influence one’s ability to pass genes on, but not in the essentialist manner of the classical view.  Rather, we have more basic ingredients for natural selection to act upon: an interoceptive system, and a conceptual system that makes meaning from interoceptive sensations in relation to the social world.  As for emotion concepts, they are created with conceptual combination, held together by words and communicated from one generation to the next.