The Cultural Microbiome

A brief introduction to Hierarchical Cultural Selection.

One of the most fascinating things about the gut microbiome is that though it is subject to competition between fauna, the major determinant of species success isn’t microbial fitness- it’s what the host eats. The initial colonization of the gut microbiome starts from breastfeeding¹, and microbe populations can be shaped by this diet to both detrimental and beneficial ends.

Similar to the gut, we must colonize infant’s minds with ideas, norms, languages, and personhood. Science has been bucking against a solely genomic explanation of personhood for decades, but of late we are starting to see discrete experimental findings via brain scanning. The advent of “cultural neuroscience” is beginning to point to potentially replicable structures that are based in nurture.

I won’t go as far as to suggest this ranges towards the discovery of a cultural replicator, on which the field of Memetics bet and lost. The search for a sole replicator was a boondoggle from the outset. Single replicator theory, or “gene’s eye" theory has been increasingly challenged in genetics. Hierarchical selection theory is still growing, even with the untimely passing of its patron Steven Jay Gould; who at times made the genes-eye theory seem foolishly like “confusing bookkeeping for causality.”²

This short article is me planting a stake in the ground, a marker that says: “hierarchical selection is real, cultural selection is real, hierarchical cultural selection is real.” Establishing and defending this idea is one of the principal goals of EoSV, and I intend to pursue it to the end.

Hierarchical Selection is real.

Cultural Selection is real.

Hierarchical Cultural Selection is real.

So, back to the microbiome. The gut microbiome is a good example of hierarchical selection at work, where competitive adaptation on the scale of individual microfauna has relatively little effect on the population distribution in comparison to active selection occurring at a higher level up in the hierarchy (hosts deciding what to eat). As with all complex systems, there is reflexivity and cross-talk that make the signal too fuzzy to simply state the gut microbiome doesn’t back-influence brain cravings. That doesn’t change the fact that the most well-adapted, craving-inducing microfauna is unable to overcome its host being tied up and force fed something else.

Much of the literature around dual inheritance theory embraces the “selection for fitness of cultural traits’ model. In attempting to universally explain the transmission of cultural traits via adaptive learning and mimicry, researchers fail to address the more specific nonadaptive patterns of learning that occur within families during childrearing and within societies during indoctrination. This is a shortsighted approach to modeling how values and norms are truly propagated through culture.

Much like the gut of a baby feeding only on its mother’s breastmilk, the brain of the same child feeds near-exclusively on its parent’s interactions. The gut suffers for lack of diversity in what it takes in. The brain suffers from the same. This is a blindspot in the prevailing desire to think cultural evolves through individual selection of useful traits to mimic, with the most useful traits being the most likely to propagate.

There is a cultural microbiome. Though its individual traits compete for reproduction and persistence, they are limited by the bottleneck of incoming information; much like populations of gut fauna are limited by the literal bottleneck of a formula container. Both individuals and and societies suffer from cultural “nutritional deficits” in the form of propaganda, misinformation, and maladaptive peer pressure.

Conclusion

We feed our minds and bodies simultaneously. Both the Environments that don’t provide full access to a healthy diet limit the development of a healthy microbiome. Truly adaptive thought can’t compete in a morass of force fed ignorance, backwards reasoning, and delusion.

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1. There’s also a competing theory that the microbiome begins transfer in-utero; but that conflicts with the uterine sterility hypothesis and doesn’t have strong experimental support.

2. There’s still blood being drawn in the streets over this disagreement; so don’t take my word as law. Here’s a great paper that attempts to refute “The Gouldian Knot”, which is a great turn of phrase. We’ll never get to see Gould’s response, because he died a few months after it was published. RIP to one of the greats.