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June 20, 2018

Three drinks for the ages

Filed under: Alcohol,Coffee,Genetics,milk,science — Razib Khan @ 9:33 pm
Irish Coffee

The “Irish coffee” is a a delicious concoction. Coffee, alcohol, and dairy. What more can you ask for? Man does not live on bread and water alone. Cafes and bars are thick on the ground in large cities, but also grace country roads. Coffee and alcohol are congenial to conviviality among settled peoples, while milk is the staff of life for many pastoralists, consumed raw or turned into cheese.

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Of the three, coffee is a new on the scene, discovered within the past 1,000 years. The consumption of milk, whether raw or as cheese, goes back to prehistory. But on the geological scale it a recent cultural development. In contrast, the imbibing of alcohol in some form is probably as old as humanity itself, albeit not as a pint in the pub.

Alcohol is produced naturally by the fermentation process, a metabolic pathway which is far more ancient than the oxygen metabolism that has been dominant for the past few billion years. Humans are omnivores, and our ancestors consumed overripe fruit which had fermented to the point of producing alcohol byproduct. Meanwhile, “good bacteria” in our guts also produced alcohol.

This is not a bad thing. Alcohol is nutritious in that it provides calories.

Though in modern societies we “count our calories”, and the richness of a deep and dark beer is not always a selling point, for the vast majority of our species’ history those calories were a feature, not a bug.

Early civilization ran on beer. The Sumerians even had a goddess of beer, Ninkasi. The workers who built the pyramids of Old Kingdom Egypt were given rations of beer. In other words, the wonders of the ancient world were fueled by alcohol!

And this is not just forgotten history. Until very recently much of the world was awash in alcohol, whether it be beer, wine, or various distilled spirits. Public and private drunkenness were one of the major reasons behind the emergence of the American “temperance” movement. Though Prohibition was deemed a failure, American alcohol consumption has never recovered to its earlier highs.

One of the reasons that Americans, and many other peoples, drank so much is that alcoholic beverages is that not only did they provide calories, but they were often more potable than conventional water. Ancient humans in hunter-gatherer bands did not have to contend to cholera, but the first village societies, and those who lived in early modern cities, lacked modern sanitation. Safe drinking water was one of the major achievements of 20th century engineering, and obviated the role that alcohol had traditionally played in quenching the thirst of the common man.

But alcohol is not a matter just of history, biochemistry and engineering. Humans differ in their ability and capacity to metabolize alcohol due to variation on their genes. In particular, ADH and ALDH2. The ADH genes produce enzymes which breakdown alcohol for processing by later biochemical steps, one of which is catalyzed by the product of the ALDH2 gene.

If you’ve ever seen someone with the flushed face characteristic of having had too much to drink, they may have a mutation on ALDH2 which means that they don’t process acetaldehyde very well. As the cells build up acetaldehyde, a host of physiological reactions kick in. Research has shown that those who exhibit these reactions are much less likely to be alcoholic.

In contrast, those with mutations on ADH tend to process alcohol very well indeed. But in the process they produce more acetaldehyde than the body can handle, resulting in physical discomfort. And similarly to the ALDH2 mutation these individuals are less likely to become alcoholic.

Genetic variation in the ability to process alcohol is a consequence of the long history of human omnivory. In contrast, the evolutionary history around our consumption of milk is much more straightforward and strange. For the vast majority of our species’ existence adults have not had the ability to digest milk sugar, lactose. This is a characteristic we share with all other mammals. The adaptive reason for this is likely that it encourages and forces weaning, so that mothers can bear other offspring.

And yet a minority of modern human adults today can digest milk. How? Why? The LCT gene produces an enzyme lactase, and mutations in this gene allow humans in Europe, parts of Southern Asia, East Africa and the Near East to continue to drink milk into adulthood. Over the past 5,000 years unique mutations in Europe and South Asia, in Arabia, and in Africa, have all been strongly selected.

In Denmark the mutant allele is now at frequencies as high as 90%.

Ancient DNA tells us that the ability to digest milk sugar into adulthood did not arise with agriculture and sedentary lifestyles. It is not implausible that Neolithic people who domesticated goats and sheep fermented milk to produce cheeses, where the sugar was broken down to make it more palatable. But the adaptation to a predominantly dairy dependent lifestyle only emerged with full-blown pastoralism, over the past 4,000 years. The earliest pastoralists on the Bronze Age Eurasian steppe carried the lactase persistent genetic variant, but only at low frequencies.

Dairy is an essential part of the modern food pyramid, at least for the USDA. But perhaps it tells us more about our evolutionary present than the evolutionary past. So often we talk about evolution as a dynamic of the deep past. But with lactose tolerance we see evolution as a process which is just initiating.

Finally, there is coffee. Though variation on the CYP1A2, Cytochrome P450, effects how fast caffeine is metabolized, coffee is such a recent cultural invention that it is unlikely that there are any adaptive dynamics related to it on a genetic level. Rather, CYP1A2 is locus which controls processes designed to cope with toxic chemicals by breaking them down. Caffeine in some ways is such a chemical, and those who metabolize it fast need to drink more coffee to feel its effects than those who have more efficient metabolization.

The effect of caffeine on humans is literally inefficiencies of bodily detoxification.

Milk nourishes. Alcohol both nourishes and alters the mental state of those who imbibe it. In contrast, caffeine does not nourish, but stimulates. For the past few million years our species likely never interacted with caffeine, but we were pre-adapted because of our consumption of a wide range of plants which manufacture chemical defenses.

The legend of coffee dates back 1,000 years, when an Ethiopian goatherd saw one of his animals behave strangely after eating a coffee plant. Within the next five hundred years coffee beans were cultivated across the hillocks of the lands around the Red Sea, from Ethiopia to Yemen, and became part and parcel of Islamic culture. To this day the coffeehouse is a major social and cultural nexus in the Middle East, though colonialism has taken it far afield, from Java to Colombia.

By the Renaissance coffee had reached Europe, and the proliferation of coffeehouses, and their stimulative effects, may have triggered the early modern Enlightenment intellectual revolution. While alcohol softens and dims the outlines of world around you, coffee is a stimulant which sharpens our perceptions and accelerates our cognitive pace.

Coffee, alcohol, and milk, are such central aspects modern culture that it is hard to imagine our existence without them. Though there is genetic variation in how we can process them, their relevance to our lives transcends biology, and extends to economics, history, anthropology, and in the case of wine, religion. Though they may not be the ambrosia of the gods, modern civilization arguably stands on the shoulders of these beverages.

Wondering if you are lactose tolerant based on your genetics? Check out Metabolism by Insitome.


Three drinks for the ages was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

May 2, 2010

The Bible tells you to avoid demon rum

Filed under: Alcohol,Culture,Data Analysis,GSS — Razib Khan @ 11:07 pm

A few quick points on the post below. When it comes to some of the natural science related posts on this weblog I put a lot of effort quite often into them. On the other hand, when I present some quantitative social science data, it’s all preliminary and exploratory. I stopped presenting regressions a while back because it took too much time to do it right, since it’s so easy to manipulate the variables into the appropriate configuration of p-value significance, even unconsciously. I provide the link to the GSS and the variables in the hope that others with some time on their hands will follow up. Together we can aggregate into a lot of labor input, if we so choose.

Now, in terms of controls for the results below, I did look into that, and I came to the conclusion (supported by some logits I ran) that the biggest influence on the patterns is BIBLE. This is the question from the GSS:

Which of these statements comes closest to describing your feelings about teh Bible?

1. The Bible is the actual word of God and is to be taken literally, word for word.

2. The Bible is the inspired word of God but not everything in it should be taken literally, word for word.

3. The Bible is an ancient book of fables, legends, history, and moral precepts recorded by men.

In other words, the variable is an index of Protestant Fundamentalism. As you can see below, separating out this category into its classes reduces a lot of the variance. A few notes. SEI = “socioeconomix index.” It runs from 17 to 97, and I combined it into three categories. On Wordsum I also combined at the extremes, since the N was small there. I also took the Census Divisions and combined them so that all the Southern regions are together, and so forth. Here’s what I input into the GSS browser:

Row: drink

Column: region(r:1-2″Northeast”;3-4″Midwest”;5-7″South”;8-9″West”) wordsum(r:0-3;4;5;6;7;8;9-10) degree region sex sei(r:17-30″Low SEI”;30.1-70″Middle SEI”;70.1-98″High SEI”)

drinkbywordsum

drinkbyedattainment

drinkbySEI

drinkbysex

drinkbyregion

As for the title, I don’t really get it. Does the Bible really place a ban on alcohol? I thought on the contrary, even taking into account Noah’s lapse into drunkenness. Instead I’m pointing here to the importance of cultural evolution in shaping norms. You can’t just necessarily take a Fundamentalist Christian who claims that the Bible is the Word of God, and therefore to be followed, at his word, so to speak.* I’m sure that some of the books that John Emerson highlighted below will explain the regional variations, though most are probably aware of the nationwide temperance movements which swept the United States in the 19th century, with the locus of energy being amongst those who we would later term Evangelical Protestants.

* Conservative American Christians like to refer to a “Biblically based society.” But really their model of society isn’t that Biblically based because the Bible’s explicit references are to an early Iron Age culture!

People of class drink alcohol

Filed under: Alcohol,Culture,Data Analysis,Drink,GSS,Stupid People — Razib Khan @ 2:20 am

don-draperOn his twitter feed one Conor Friedersdorf made a comment about how beer unites people across the ideological spectrum. I raised my eyebrows at this, because I know that a substantial number of Southern white Protestants do not drink alcohol. With a name like Friedersdorf I suspect that Conor probably didn’t consider this because of the normative nature of beer consumption in his social circles. I’ve always meant to look into the differences in alcohol consumption by demographic because I’m sure you’ve seen all the medical “studies” which claim that drinking in moderation has benefits toward your health. The main concern I have is that a lot of these seem to be correlational studies (though not all), and there are also often conflicts of interest with the funding (the alcoholic beverage industry is naturally happy to front the cash to pursue research so as to make the correlation firmer in the public mind). Now, I have nothing against alcohol personally, I like dark beers and white wines. But I’m a little skeptical when people promote health benefits of a class of product with which a non-trivial minority of the population have substance abuse issues.

To sate my curiosity, I decided to look at the GSS. So you can replicate, here are my variables:

Row: Drink

Column: Year Race Sex Region God(r:1-3″Non-theist”;4-5″Believe, But Doubts”;6″Know God Exists”) Relig Polviews Degree Wordsum

Some of the variables are obvious, but in regards to the somewhat garbled gibberishy looking section I “recoded” it  so as to combine classes with very small N’s and such. Since you have the variable names you can follow up and see what I did if you’re curious.

Here are some results….

Not too much change over the years.

drinkyear

Now, some demographic variables of interest. Not too surprising. I knew that blacks were more likely to be teetotalers, and expected that women would be as well. Note the big difference by religion.

drinkdemcat

As I said, people in the South are less likely to drink. This partly tracks religion, but I’ve poked around these particular data and in New England both Catholics and Protestants drink a fair amount, so it is a regional Protestant subculture which is fostering teetotaling (here are the labels geographically by the way).

drinkregion

Some more variables, though note the spectrum. The conservative tendency toward teetotaling probably has something to do with the correlates of extreme conservatism (higher religiosity, tendency to live in the South, be Protestant, etc.). Keep an eye on the education though….

drinkideology

This chart pretty much floored me.

drinkwordsum

I was expecting it. That is, that the more intelligent, who scored high on a vocabulary test, would drink more than the dumb, who scored low. Look at the other correlates above. But I’ve rarely seen such a stark near-monotonic trend with Wordsum.

You can try to control for variables. Race doesn’t matter much for what it’s worth, the trends stay pretty much the same if you constrain to whites. I decided to check the “Bible” variable, which measures literal interpretation. As expected controlling for fundamentalism eliminates much of the Protestant vs. non-Protestant difference, as well as exacerbates the sex difference (fundamentalist women are much more teetotaling than men), but it really didn’t effect the rank relation on many categories. The regional and Wordsum difference remains even among those who are fundamentalists or irreligious. I think this points to the social aspect of drinking. Even if you like to drink, if you’re circle of acquaintances tends not to, you won’t get a chance to drink as much. Conversely, if drinking is expected, there’s more pressure to bend your norms to please your friends.

Anyway, just be careful of studies extolling the virtues of alcohol unless they control for confounds. It’s just a fact that stupid people tend to die earlier, because they often make life decisions in keeping with their nature.

Image Credit: AMC

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