Fermented Foods in Human Biological and Cultural Evolution

The Raw and the Rotten (1)

One third of the calories consumed worldwide come by way of fermentation. Moreover, there is no culture on this earth that eschews fermented foods. Fermentation is what Evolutionary Psychologists like to call a “human universal” Why? What is it about fermented foods that is so universally ingratiating. How could a process of microbial rotting be anything but bad for human health? For insight, in this regard, it helps to look inside our guts.

Most by now have at least heard of microbiomes, the myriad microbes that inhabit our bodies, without which we could not exist. (The number of these microbes far exceeds that of our own cells.) They are not evenly distributed. Hot spots include the skin, vagina and large intestine. The latter contains by far the most. Most significant for our purposes is what these gut microbes do, which is ferment. From these internal fermentations are derived all manner of essential nutrients. Bad things happen when these essential nutrients disappear, and not just in the gut. Among the host of physiological problems that result from dysfunctions in the gut microbiome are obesity, diabetes, cardiac diseases and more.  Included in the “more” are depression, anxiety and other psychological disorders. Closer to microbiomic home are gut ailments, such as Chron’s Disease and Irritable Bowel Syndrome.

In order to prevent these maladies, we are instructed to consume foods that make life easier for our gut microbes. Opinions vary widely and stridently as to what those good for your gut foods are. Many have turned to nutritional supplements in capsule form. These supplements are marketed in three categories: prebiotics, probiotics and postbiotics. Of these probiotic supplements are the most familiar.  They are supposed to contain live microbial reinforcements for the internal gut microbes. Prebiotics, on the other hand, provide the raw materials, mostly plant fiber, upon which the gut microbes rely. The third P, called postbiotics, provide exactly the same nutrients as the gut microbes, thereby lightening their load.

All of these pre, pro and postbiotic benefits can be had in fermented foods, externally modified by microbes through the same process used by our internal gut microbes. Call this “outsourcing”. We humans have been outsourcing the work of our gut microbes for millions of years. Some believe outsourcing is responsible for the two most striking anatomical differences between us and chimps—our much larger brains and our much smaller guts, an idea we will explore in subsequent posts.

Genomic research reveals that we have evolved to take advantage of fermented foods. One of the two basic types of fermentation results from the activities of lactic acid bacteria. (This is the kind of fermentation that occurs in our guts.)  One adaptation to acidic fermentation is an affinity, unique among primates, for sour foods. Another is a new taste receptor that responds specifically to byproducts of acidic fermentation.

Our biological predisposition for the fermented extends to alcoholic fermentations as well. We are exceptionally alcohol tolerant; even the least alcohol tolerant among us can tolerate alcohol levels that would kill all but a handful of other mammals. This too is a biological adaptation that extends back millions of years, when our ancestors came down from the trees. On the ground they found a host of new foods, including fermenting fruit. One byproduct of alcoholic fermentation is ethanol. Initially ethanol was ingested inadvertently but later deliberately manufactured by various means, for both nutritional and non-nutritional consumption.

The foregoing concerns what is biologically universal about our relationship with fermented foods. But that’s less than half the story that will be told here.  The bulk of the book concerns the incredible cultural diversity of fermented foods. We can trace, in broad geographic outlines, some of this diversity back to a point in time when all humans were so-called hunter-gatherers (henceforth foragers), well over 10,000 years ago. The resolution of this picture improves as we approach the present day. The fermented foods consumed by we humans became increasingly culture-specific, to the point that Americans are disgusted by much of the fermented fare available in the rest of the world.

For most of the world fermentation remains artisanal. Artisanal fermentations are spontaneous (also called “natural”), the work of indigenous microbes that colonize the raw material. In the West fermentation has become increasingly industrialized and far from spontaneous. Instead, pre-packaged starter cultures of mostly non-local microbes are deployed in order to increase efficiency, the most fundamental imperative for any form of industrialization. Two diametrically opposed responses to industrialization will shape the future of fermented foods in the West. One, represented by the indefatigable Sandor Katz advocates for a de-industrialization and a return to artisanal fermentations. In stark contrast, buoyed by breakthroughs in genetic and genomic research on the microbes responsible for fermentation, are many who seek to take industrialization to another level. Advocates for this approach lobby to employ genetically engineered microbes to further increase efficiency and produce new nutrients. The choice is not as simple as it may seem.