This is the last of 3 blogposts pertaining to evolutionary mismatch as it relates to addictions and behavioral compulsions.
In the previous post, I discussed sugar, fats, and salt as essential food components which have been exploited by modern companies which produce a plethora of varieties of junk food. However, there was one issue that I deliberately omitted, and that is the connection between ripening fruit, ensuing fermentation of ethanol (alcohol) by the yeast cells that are ubiquitous in the air, and our historical tendency to seek out sources of alcohol as a rich source of calories.
Dudley (2000) suggests that “low-level ethanol ingestion was an important feature of human nutrition over evolutionary time.” You can see him articulate his main points on the “drunken monkey” hypothesis in the video entitled “Why do we drink alcohol? The Drunken Monkey Argument”, which you can access via https://www.youtube.com/watch?v=87FOhjLK4yc. In the original article, he states that a number of predictions ensue from the “drunken monkey” hypothesis and provides some empirical evidence:
| Prediction | Supporting Evidence |
| Ethanol occurs naturally at low levels within many fruits and nectars. | A variety of tropical fruits, as well as some nectars, contain ethanol at low concentrations. |
| Olfaction can be used to localize and preferentially select ethanol-containing nutritional sources. | Fruits consumed by primates produce numerous volatiles, including ethanol. Olfactory abilities are well-developed in primates. |
| Ethanol at low concentrations is not aversive to frugivores and nectarivores. | Diverse vertebrates consume food items containing low-concentration ethanol. |
| Ethanol acts as a feeding stimulant. | Modern humans increase caloric ingestion following consumption of an aperitif. |
| Genetic variation in the ability to metabolize ethanol is correlated with the extent of dietary exposure. | Substantial variation in ADH (Alcohol dehydrogenase) tracks dietary inclusion of fruit and nectar among mammals. Ethanol catabolism was up-regulated in African apes ~10 Mya ago, in parallel with terrestrialization. |
| Hormetic advantage derives from chronic consumption of ethanol. | Mortality is reduced at low levels of ethanol ingestion in modern humans and rodents, and also in Drosophila flies exposed to low-concentration ethanol vapor. |
So arboreal primates, which are frugivores, were exposed to very low concentrations in the fresh fruits that they would ingest. For example, ripe palm fruits (Astrocaryum standleyanum) contain 0.6% ethanol within the pulp, but over-ripe fruits have levels of ethanol averaging 4.5%. have The evolution of terrestrial primates, including hominids, from their tree-dwelling ancestors coincided with a time of great climatic change in the Serengeti rift area of Africa. Rainfall is this area declined so large areas of lush forestland gave way to spotty forests and expanding grasslands.
As these arboreal primates descended from the trees to the ground, they were exposed to older, over-ripe fruit which had been colonized by yeast cells which, in turn, started to ferment the sugars to turn them into alcohol.
Any animal which could tolerate and metabolize the increased concentration of alcohol in fruit could therefore have a rich source of carbohydrates. The crucial event, a mutation in an alcohol dehydrogenase (ADH) gene yielded a form with enhanced catabolic capacity, and occurred about 10 million years ago (Mya), before the separation of the hominid line from the great ape line.
So hominids now have two significant abilities:
- To be able to metabolize alcohol at the concentrations found in fermenting fruit;
- To be able to detect alcohol from the plumes emitted from fermenting fruit, which would represent a transient resource in a heterogenous environment.
We have already seen that the human preference for sweet taste is an innate characteristic (Davis, 2014), but the detection of the fragrance of alcohol will help locate the location, and alcohol has certain advantages:
- Alcohol has antibacterial properties;
- Small amounts of ethanol can act as an appetite stimulant;
- It can facilitate social behavior, conducive to reproduction and safety;
- It has the ability to reduce social inhibition, anxiety, and discomfort, and to increase communication and intimacy.
Dudley and Maro (2021) then argue that there is evidence among studies of several animals, including fruit flies, laboratory rodents and humans, that there is an optimal daily intake of alcohol, below which there is either decreased fecundity (as in fruit flies) or increased mortality. “In humans, epidemiological studies suggest a reduction in cardiovascular risk and overall mortality at low levels of ethanol consumption relative either to abstinence or to higher levels of intake.”
Therefore, the evolutionary background of alcohol consumption by hominids suggests the following:
- The development of a form of alcohol dehydrogenase (ADH) which could efficiently metabolize alcohol into acetaldehyde, the first step of metabolism, occurred before the hominid line separated;
- This form of alcohol dehydrogenase allowed hominids access to a source of carbohydrates which could not be utilized by arboreal primates;
- The ability to detect the alcohol plume from fermenting fruit allowed hominids to find these sources of carbohydrates;
- There is an optimal daily dietary consumption of ethanol.
The mismatch starts with the advent of farming and agriculture
Perhaps we can attribute the evolutionary mismatch to a side effect of farming, for with farming came the ability to deliberately produce beverages containing ethanol. Humans have invented alcoholic beverages many times independently. For example:
| What kind of booze? | Where? | When? |
| Rice wine | China | 7,000 BC |
| Wine | Caucasus | 6,000 BC |
| Beer | Sumerians | 3,000 BC |
| Aztecs | pulque from the same agaves used today for tequila | N.A. |
| Incas | chica, a corn beer | N.A. |
In most cases, the concentration of ethanol in fermented drinks is higher than the 4.5% noted in over-ripe palm fruits, so I think we can assume that current alcoholic beverages have far higher concentrations of ethanol than what our deep Pleistocene ancestors would have ever encountered:
| Type of alcoholic beverage | Concentration of ethanol |
| Beer | 4-6% |
| Light beer | 2-4% |
| Malt liquor | 6-8% |
| Wine | 14% |
| Hard cider | 5% |
| Mead | 10-14% |
| Sake | 16% |
As you may surmise, different civilizations had very different drinking cultures. For example:
China
(https://www.theworldofchinese.com/2021/08/drinking-in-ancient-times/)
- In her article, Wang Lin describes how citizens enjoyed fine wines for all occasions, and would become poetic in their appreciation. They also stressed timing when it came to appreciating wine. “When it rained in spring, one drank while enjoying the greenery. When it snowed in winter, friends gathered around a cozy fire to chat and laugh over a pot of warm wine.”
- They would also play drinking games, as in the following: “Before the banquet, the guests were seated elegantly. After a while, many stood up with musical instruments and start to dance freely. In the Tang dynasty (618-907), a game called touhu (投壶), or “pitch pot,” was popular at banquets: People shot arrows into a wine vessel, and the one who missed the pot had to drink more. Instead of drinking blindly, why not make it a game for everyone?”
Egypt
- The Egyptians enjoyed drinking alcoholic beverages as part of their leisurely activities, but alcohol played an important role in their daily lives and religion. For most Egyptians who were not fortunate enough to be nobles, alcohol was the primary drink in their diets. Alcohol was also significant in ancient Egyptian religion as it played a central role in some of the myths and was commonly used in most rituals.
- All classes of ancient Egyptians consumed wine and beer for leisure and pleasure in different settings. The wine was favored by the royals for its taste, as well as its intoxicating effects.
- Modern scholars believe that wine production probably began even before Egypt was a unified state around 3100 BC. Still, by the Old Kingdom (ca. 2686-2181 BC), there was a full-fledged wine industry in Egypt. [4]
- Moderation was actually frowned upon as drunkenness was a sign of wealth and abundance.[5] Binge drinking was an acceptable past-time not just for the upper classes of Egyptian society, workmen and peasants also liked to let loose on special occasions.
Greco-Roman world
https://classicalwisdom.com/culture/traditions/alcoholism-greco-roman-world/
- In both the ancient Greek and Roman world, alcohol was an important element often taken for pleasure, for social reasons, and for medicinal purposes. However, as the Roman Empire grew, drinking began to change. The Romans’ traditional values that were modeled on those of the Greeks—such as frugality, temperance, and simplicity—were slowly replaced by heavy drinking and other vices, including degeneracy, blind ambition, and corruption.
- The consumption of wine was famously a part of the Greek Symposium, an important Hellenic social institution during which young men were introduced into aristocratic society. Men of respected families engaged in discussions and debates while wine was served. At a Greek Symposium, women weren’t allowed and wine was taken after dinner. At the similar Roman Convivium, wine was served before, during, and after a meal, and women were allowed at the gathering.
- Followers of Dionysus, the Greek god of wine, believed that becoming intoxicated brought them closer to their deity.
- The Macedonians also, among Greeks, perceived intemperance as a sign of masculinity, so men could drink to intoxicate themselves. Alexander the Great is a famous example, and may have died as a result of his habit.
Hindu
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4776591/
- Of all the multifaceted problems in India, the drink evil is the oldest one and indeed steeped in antiquity. The discovery and art of manufacturing some kind of intoxicating liquor are a corollary of settled habits and wandering savages have generally been found ignorant of it.[3] This proves the fact that we had a settled and advanced civilization. Such habits were prevalent in the earlier Egyptian, Babylonian, and Greco-Roman civilizations. It may be stated that, except for gambling, the greatest vice of the Aryan race in India was drinking.[4] Rig Veda is the most ancient and extant literature available to us on this subject. According to historians, both Western and Indian, these hymns in the praise of the various Aryan gods such as Indra, Varuna, and Agni were collated by various sages such as Angiras, Brihaspati, Bharadvaja, Vashistha, and Gautama during 1500-1000 BC. There are innumerable passages in ancient Sanskrit literature that prove conclusively this weakness of our ancestors,[5] and the Rig Veda Samhita has a hymn which shows that “soma (wine) was kept in leather bottles,[6] and freely sold to all comers.” It may be added that soma was freely consumed. Passages after passages in the Rig Veda are given to the praise of soma,[7] the liquor, which was afterward incorporated with the worship of soma – the moon god.
- Elaborate rules for the preparation of this intoxicating liquor are still to be found, which show the hold that the liquor had on the elite – if not the common people.
Norse/Viking
- “Mead, a honey-based alcoholic drink, was widely consumed by the Vikings and thought to symbolize strength, courage, and fertility. Beer made from barley or wheat was also popular among them; weaker than modern-day varieties, it was often mixed with herbs or honey for flavor. It appears beer was regularly enjoyed at feasts and gatherings for its taste as well as its perceived medicinal benefits.”
- “Alcoholic beverages were not only used for pleasure; they also served as currency among the Vikings. Mead could be traded for goods or services and even offered up as tribute during raids on foreign lands. This hints that drinking held a place of importance in Viking life and culture – though overindulgence was not tolerated due to the potential disruption it posed to order.”
- “Vikings had an affinity for drinking games such as ‘Hnefatafl’ (similar to chess) or ‘Kubb’ (akin to lawn bowling). Drinking competitions were also commonplace during gatherings, with the victor being crowned King or Queen of the feast. These contests usually involved physical challenges like arm wrestling or ax throwing. Furthermore, when attending a ‘blót’ (offering made to gods), it was customary for members of the community to bring mead or ale that could be shared amongst those present. This practice was believed to be a way of uniting them together in reverence to their faith.”
(BTW, yours truly had great fun reading the text on Norse/Viking drinking culture.)
The concentrations of alcohol in the beverages available to the cultures mentioned above are trifling, compared to the concentrations of ethanol attainable through distillation:
| Type of distilled alcohol beverage | Concentration of ethanol |
| Gin | 35-55% |
| Brandy | 35-60% |
| Whiskey | 40-50% |
| Rum | 40% |
| Overproof Rum | 75.5% |
| Tequila | 40% |
| Vodka | 40% |
| Absinthe | 40-90% |
Allow me to end this blog with the lyrics to the Doors’ cover of the Alabama Song:
Alabama Song (Whisky Bar) Lyrics
[Verse 1]
Well, show me the way
To the next whiskey bar
Oh, don’t ask why
Oh, don’t ask why
Show me the way
To the next whiskey bar
Oh, don’t ask why
Oh, don’t ask why
For if we don’t find
The next whiskey bar
I tell you we must die
I tell you we must die
I tell you, I tell you
I tell you we must die
[Chorus]
Oh, moon of Alabama
We now must say goodbye
We’ve lost our good old mama
And must have whiskey, oh, you know why
Oh, moon of Alabama
We now must say goodbye
We’ve lost our good old mama
And must have whiskey, oh, you know why
Yeah
By the way, the Doors version is a cover of a much older song: https://www.youtube.com/watch?v=EGUjGPrfA6U
And here is David Bowie’s take on it (1978): https://www.youtube.com/watch?v=5ibH-BkZg0o
Dudley, R. (2000). Evolutionary Origins of Human Alcoholism in Primate Frugivory. Q. Rev. Biol. 75, 3-15.
Dudley, R.; Maro, A. (2021). Human Evolution and Dietary Ethanol. Nutrients 13, 2419. https://doi.org/10.3390/nu13072419
Longrich, N. (2021). When did humans start experimenting with alcohol and drugs? https://the conversation.com/when-did-humans-start-experimenting-with-alcohol-and-drugs-161556#
Addictions and Recovery 