Why Milk?

Throughout evolutionary history, most adult homo sapiens could not drink milk. Even today, most adults cannot drink milk. Adults who cannot drink milk don’t seem to lose very much, particularly as they can still eat yogurt and cheese. And yet the gene that allowed some adults to drink milk spread incredibly rapidly suggesting massive advantages to milk drinkers. Why? No one knows for sure but it seems to coincide with civilization. Slate has more:

[A]round 10,000 B.C….a genetic mutation appeared, somewhere near modern-day Turkey, that jammed the lactase-production gene permanently in the “on” position. The original mutant was probably a male who passed the gene on to his children. People carrying the mutation could drink milk their entire lives. Genomic analyses have shown that within a few thousand years, at a rate that evolutionary biologists had thought impossibly rapid, this mutation spread throughout Eurasia, to Great Britain, Scandinavia, the Mediterranean, India and all points in between, stopping only at the Himalayas. Independently, other mutations for lactose tolerance arose in Africa and the Middle East, though not in the Americas, Australia, or the Far East.

In an evolutionary eye-blink, 80 percent of Europeans became milk-drinkers; in some populations, the proportion is close to 100 percent. (Though globally, lactose intolerance is the norm; around two-thirds of humans cannot drink milk in adulthood.) The speed of this transformation is one of the weirder mysteries in the story of human evolution, more so because it’s not clear why anybody needed the mutation to begin with.

…A “high selection differential” is something of a Darwinian euphemism. It means that those who couldn’t drink milk were apt to die before they could reproduce. At best they were having fewer, sicklier children. That kind of life-or-death selection differential seems necessary to explain the speed with which the mutation swept across Eurasia and spread even faster in Africa. The unfit must have been taking their lactose-intolerant genomes to the grave.

…The rise of civilization coincided with a strange twist in our evolutionary history. We became, in the coinage of one paleoanthropologist, “mampires” who feed on the fluids of other animals. Western civilization, which is twinned with agriculture, seems to have required milk to begin functioning. No one can say why.

Hat tip: John Chilton.


My guess (and it is only a guess): as agriculture and hence population increased (agricultural societies can produce many more calories per person than hunter-gatherer societies, allowing population to increase) and diet increasingly shifted from protein- and fat-rich foodstuffs (dead animals) to protein- and fat-poor foodstuffs (grain), leading to malnutrition problems (there ain't no such thing as dietary essential carbohydrate, whereas humans must ingest sufficient amounts of protein and fat to survive), those who could drink milk were at an advantage because they had an additional, relatively plentiful source of protein and fat, and therefore were healthier and could out-reproduce their neighbors.

But, as with almost all evolutionary things, it's probably much more complicated than that...

This sounds very plausible to me :)

Also the transition from hunter-gatherer to agrarian societies was marked by the domestication of not just crops but also livestock (mainly wild cattle). No wonder we see the milk-tolerance emerging at around the same time people started producing food (circa 10,000 BC).

Your guess sounds extremely reasonable.

This and many of the theories posited below do a good job explaining why milk-tolerance would be a strong evolutionary advantage.

But none seem to address how this gene would spread so rapidly compared to the time scale of other typical mutations. To me that seems a key point begging for an explanation.

I think a missing part of the explanation may be cultural. If a lot of people start drinking milk as adults and adolescents, then soon everyone will be expected to drink milk. So perhaps people who were lactose intolerant died off quickly in part because they were drinking milk, and getting fewer calories from other sources.

Faster than the usual Fisher-Kolmogorov wave?

Military conquest?

To raise an army (really a militia or raiding party at this level), you need lots of healthy young men, which means you need lots of calories and lots of protein. Once you've mastered basic agriculture, calories come relatively easily and protein is the bottleneck. Given persistent conflict between adjacent tribes, villages, city-states, whatever, the ones which generates the most usable protein per acre havee a better than even chance of owning all the acres in a few generations.

Here and now, I believe the absolute highest protein-per-acre productivity on average farmland comes from corn (ie. maize) fed dairy cattle, by a significant margin. The closest competitor is probably soybeans - native to East Asia, where lactose tolerance never took off. Mind you, I'm talking here about modern crops/livestock, requiring thousands of years of selective breeding and global trade. But it may well be that, in Europe and Central Asia ca. 10,000 BC, grass-fed goats or proto-cows were the best protein-per-acre producers, if and only if you could drink the milk as well as eating the meat.

If your tribe doesn't drink milk, you are killed or enslaved by the more numerous warriors of the neighboring tribe that does. If your tribe does drink milk, you gain reproductive access to the enslaved women of the neighboring non-milk-drinking tribe. Sounds like a basis for extremely rapid genetic success, though it would require more study of early agricultural yields to pin down with real confidence.

Yet it wasn't necessarily a significant disadvantage for lactose-intolerant as they could still consume yogurth and cheese.

I think they could consume *some* yogurt and *some* types of cheese. I've read a few discussion boards on making your own yogurt at home. Lactose intolerant people seem to report that simple overnight fermentation of the milk is not enough to reduce lactose levels to tolerable amounts. Instead, they must filter the yogurt (retaining the solids) to remove most of the whey before lactose gets low enough. I can imagine that softer cheeses might also contain a significant amount of lactose.

So all the work to convert milk to lactose-free yogurt and/or cheese is quite significant, as Greg Ransom notes.

My guess is that drinking milk is not a particular advantage per say and only came to dominance as it is not recessive. I think we over do the idea that some trait comes to performance just because it is so superior to all other traits when in fact it could just be piggy backing on some other thing. White skin is held to be an advantage because it allows you to get vitamin D easier. And yet the Japanese don't seem to suffer even thought they do not get more sun then France. Some of the just so stories we tell have only a shaky basis on observed fact.

Sapporo, the northernmost major city in Japan, is at roughly the same latitude as Marseille, at the far south of France. Most of Kyushu lies further south than Gibraltar. Moreover, many Japanese people are quite light-skinned. I don't think they're any darker on average than Spaniards, Turks, Greeks, or Italians.

Direct milk consumption radically shortens the production time structure.

Read some economics,

This is economics 101.

Shorter production process = productivity gain / savings

The fact that economists don't understand the basic choice logic of production is very damaging to the economic waymofmthinking.

People won't undergo the cost of extending the length of production unless extending the length of the process promises superior output.

In terms of calories and nutrition and time of production, cheese can't match milk.

Econ 101.

Read some Bohm-Bawerk.

This comment is remarkably free of actual content. The lines between the sentences are as useful as the sentences themselves.

He could've just said "it saves labour". Expanding three words into READ BOHM BAWERK! naturally makes the signal-to-noise ratio bad...

The issue isn't labor.

You've just put a "I HAVEN'T READ BOHM-BAWERK" sticker on your back.

"Unless extending the length of the process promises superior output"

I would say that being able to consume cheese but not milk makes cheese a superior output.

And, no, I have not read Bohm-Bawerk, which doesn't excuse you're inability to explain the same.

It isn't *labor* thats being saved but risk and time due to shortening the supply chain.

we would have done better with a mutation to produce cellulase, digest grass directly, & bypass the cows...

or better yet, have photosynthetically active green skin, & absorb our nutrients direct from the sun...

Not to mention the Orion girls were HOT.

I suspect there is a fair amount of jest in your comment, but still, regarding your second suggestion... Erm, nope, we would not have done better. Photosynthesis is not a very efficient way to power an organism (hence the whole concept of ecological pyramids). Just a green skin would provide a very small supplement of the nutrition of a human being, while being costly in complexity terms - you'd need to evolve the whole metabolic chain of photosynthesis.

He/she would need to adopt a certain changes in order to make it worthwhile:
1) increase skin area, i.e. develop leaves
2) minimize movement to save energy and not break above-mentioned leaves
3) secure an uninterrupted supply of water (CO2 is easier) for photosynthesis, which is a major problem when you do not move - thus, he/she needs to dig in, i.e. develop roots
4) outsource the finding of similarly immobile mates, i.e. develop flowers to attract insects.
5) protect its vital structures from predators, i.e. develop bark.

I am sure you see where this is going. The little green men live among us - we call them trees.

As a matter of fact, a photosynthesizing animal is not impossible (see here) - it's just severely limited in terms of size and habitat (water helps mobility via Archimede's principle).

Moving back towards the bottom of food chain is at best a niche strategy.

See http://what-if.xkcd.com/17/ "If cows could photosynthesize, how much less food would they need?"

Milk can't be stored for very long, especially not without refrigeration. Hipster milk drinkers in Sweden are buying a whole lot of unpasteurized fat milk labeled "traditional", even though almost nobody drank milk before the industrial revolution since it was extremely wasteful to not make butter or cheese out of it.

Really? Nobody? Didn't like 90% of the population live on farms??

You are incorrect. Milk drinking dropped off after the industrial revolution, because people moved to cities yet there was no refrigeration.

If you're saying that:

1. It takes time and effort to turn milk into cheese and yoghurt.
2. These were, at least initially, risky and uncertain processes.

Then that makes sense. I don't know why the idea, at least, requires deep study to understand.

I'd also wonder about technology. Is it possible that the genetic advantage of being lactose tolerant was already in place by the time knowledge of cheese and yoghurt making spread widely? I don't know.

Storage of milk in the bladder of goats and such is the hypothesis I've heard for the process behind cheese making.

Is there any rival to that theory?

And if that is the causal pathway, it looks like we have milk drinkers before we have cheese eaters.

Lactose intolerance is the kind of thing you'd only find in mammalian adults if if being tolerant were selected against, which you'd figure it was since enzymes aren't free. So you could have some tolerants before milk drinking, but not a lot.

And it doesn't just take time, it reduces caloric content.

This isn't clear at all.

And you are mixing up biology with the economics of chice.

We are combining economic thinking, eg the logic of choice over alternative time-length production processes & outputs, with selective adaptation thinking, ie the logic of alternative reproductive consequences of alternative adaptive traits.

The biological payoff has to be biological, eg differential nutritional advantage with differential reproductive consequences.

The economic side of the situation helps us understand the existence or lack of the existence of a choice situation on the production side -- only those with the lactose-tolerance gene get the advantage of having the alternative of trade off between choosing higher nutritional output with no time wait, or expending resource to get few nutritional benefits but perhaps other benefits after expending time, labor and deferred resource use, eg the benefits of the storage properties of dried cheese.

The adaptive benefits of either of these two productive choices could then have selective/adaptive consequences of their own, eg biological changes in taste, for example.

Your econ 101 course covered the details of milk production and the calories of raw milk relative to cheese?

You sure it was econ 101 you were taking, and not food technology 304?

Sorry you don't get the Econ. Let me recommend Bohm-Bawerk.

This is discussed at length in The 10,000 Year Explosion:


The authors note that one can extract about 5 times as many calories from a cow by milking it its entire life than one can by slaughtering it alone; so individuals with adult expression of lactase would've had an enormous advantage as herders. They further argue that the Proto-Indo-Europeans had a high incidence of adult lactose tolerance, and spread the trait rapidly by conquest West from the Steppes.

Since the number of cows is not fixed, the question is not whether you can extract more calories from a given cow but whether a dairy cow is a more or less efficient way of transforming vegetable calories to protein and fat. A dairy cow over its lifetime produces more than a slaughtered steer -- I'll stipulate that -- but it lives a lot longer and presumably eats a lot more.

I don't know the answer to that question. However, that is the right question to ask.


The correct quote is "about five times as many calories per acre."

"The authors note that one can extract about 5 times as many calories from a cow by milking it its entire life than one can by slaughtering it alone"

That's not really a valid comparison, since a breeding cow can have calves and the rancher can eat them. Indeed, a milk rancher given unlimited land would still eat about half the offspring (the males). However, no one has unlimited land, so the advantage is just the net milk that the calves don't require in a full sized herd. I'm not sure the caloric difference is enough to account for such a rapid spread of the gene. Perhaps there were other factors at work?

I think this nails it.
The authors note that one can extract about 5 times as many calories from a cow by milking it its entire life than one can by slaughtering it alone; so individuals with adult expression of lactase would’ve had an enormous advantage as herders. They further argue that the Proto-Indo-Europeans had a high incidence of adult lactose tolerance, and spread the trait rapidly by conquest West from the Steppes.

i LOVE milk.

Per se--Latin--- in itself. Per say--??

I've always hated milk, even as a child. Now I save the calories for alcohol.

Protein(casein)--4 calories.
Carbohydrate(lactose)--4 calories.
Fat--9 calories.

Alcohol--7 calories.

The other 2 calories in alcohol come from the liver frantically converting (detoxifying) it to a carbohydrate(acetic acid) because it is a potent neurotoxin that can cross the brain-blood barrier. Bon appetit.

Acetic acid is not a carbohydrate; it's closer to a lipid than a carbohydrate. The 2 fewer calories in alcohol (per gram) stem from the fact that it is a very short-chain molecule, so the non-caloric oxygenated end of the molecule makes up a higher percentage of the total molecular weight than compared with lipids. And also your definition of "potent" seems a bit weird. What other neurotoxins require multi-gram doses to have any effect?

Lastly, when my liver does it, it's definitely not "frantic". Maybe you're doing it wrong?

I'll agree about "potent". It does take a lot compared to Mescaline(400mg) or LSD(400 micrograms).
The liver regards acetic acid as a carbohydrate. CH3COOH = C2H4O2 = C2 +2H2O. ( "=" are not reaction arrows just equivalence designators) and knows the muscles will burn it as a carbohyrate. Only the liver can "burn"(detoxify) alcohol. Maybe you're doing it wrong.

Despite stoichiometric equivalence to a carbohydrate, acetic acid doesn't go through glycolysis, and can't be used for any substrate-level phosphorylation (therefore it can't be fermented like most sugars). Into the TCA cycle (or into lipid biosynthesis) are the only two major places it can go.

Curt, it's been a long time and you're obviously more informed on this than I, but "Into the TCA cycle (or into lipid biosynthesis) are the only two major places it can go" equivalent(except for the lipid biosynthesis)to what us mere mortals would cal l"burning it like a carbohydrate"?

athEist -- Well, acetate is neither a lipid nor a carbohydrate, so in some sense we're both wrong. To your question, going into the TCA cycle is where stuff gets converted to CO2, so it is "burning it", but lipids (and in some cases proteins or amino acids) can also go into the TCA cycle. So you could equally well say that acetate "gets burned like a lipid" or "gets burned like a protein".

It's all a bit subjective but I do think acetate is more like a lipid than a carbohydrate, for the reasons I mentioned. But you're right that acetic acid is C2H4O2, which makes it look like a carbohydrate, and that it can be burned, and by muscle no less.

And of course a cow can live on grass and weeds thus opening a otherwise inaccesible dietary resource.

I remember from college 20+ years ago that this was presented as a solved problem in a human biology class. My memory is... The percentage of adult lactose tolerant population became almost perfectly correlated with latitude. It was therefore thought to be related to calcium absorption. Both vitamin D and lactose (when ingested with calcium) promote absorption. Obviously, people in higher latitudes have periods of the year where there is insufficient sunlight to produce an adequate amount of vitamin D. So being able to consume milk is a huge advantage in those latitudes/

The two major outlier populations where eskimos and bedouin. Eskimos consumed the livers of sea mammals year round which are very high in Vitamin D (and obviously winter herding of land mammals is less feasible). Bedouin were a bit of mystery but the hypothesis was that it provide them some sort of hydration/electrolyte advantage in the harsh desert climate.

Again, this is all from memory of a class decades ago but it was presented as if this was a well known solution.

There were only two exceptions, bedouin and eskimos.

So it's a theory that fails for the Americas, East Asia, Australia, north Africa, and most of South Africa?

I too bought the conquest mechanism in 10,000 Year Explosion.

Drinking milk means converting precious food calories in the form of grasses otherwise not consumable by humans, into a human consumable form. It's obvious why this would have been advantageous.

A huge percentage of the calories from milk are lost during fermentation. Drinking milk would have provided many more calories than eating yogurt or cheese.

Yes, those bacteria don't convert milk to cheese for free. They consume all the lactose, nearly one fourth of its caloric value.

They don't fully consume the lactose; they convert it to lactic acid. The laws of thermodynamics being what they are, this does consume some energy, but I'm pretty sure it's a fairly small percentage IIRC, full metabolism of lactic acid generates something like ten times as much ATP as glycolysis.

Yes, yogurt and cheese have disadvantages -- higher cost -- than milk, as measured by the calories obtained, the time cost a la Bohm-Bawerk, and the extra labor required.

But they have a huge advantage: they last longer without spoiling than raw milk does. Giving people the ability to detach consumption from production across time, instead of having to consume the milk in a day or two.

Being able to store calories in the form of cheese (and grain, and salted or smoked meat) can mean the difference between surviving a winter, or a year of drought, and starving to death.

The authors of "The 10,000 Year Explosion" have a blog, and a recent post on the origin of the term "mampire". I asked there why lactase persistence was so highly selected despite fermentation, and Henry Harpending responded.

It's just a precautionary preparation for being ready to eat ice-cream.

You spelled "Chocolate" wrong.

Real chocolate has no lactose.

Could disease have something to do with it? I imagine disease became a much bigger problem with the rise of denser populations of "civilization".

Could milk drinkers have avoided contaminated water supplies? I am not an expert on these things, but my impression was that traits could spread very rapidly when disease got involved (the whole dying early thing).

"Could milk drinkers have avoided contaminated water supplies"

One of the top causes of death for children, was iirc water borne disease.

We humans obviously start out with a gene for producing lactase, so it's not the case that we developed the ability to digest something we never could in the past. Is this really a genetic "mutation" or something simpler: the lactase gene merely stays active rather than switching off. That doesn't require an actual change to the genetic code: the gene for lactase is the same it just doesn't go dormant in some people.

It's a mutation - an actual change to the genetic code. . A single causative mutation in a wide stretch of Eurasia, a different one in Bedouins, several different ones in east African pastoralists.

I don't how see this in the mutation-- not in the sense that some people have a gene that other people do not have. Everyone has the same (in the generic sense) lactase gene. In some people it goes dormant after early childhood. In others it remains active throughout their life. The mutation, if you want to call it that, is in how the gene works, not in its chemical composition. Hence the change may not be a genetic one at all, but something farther up the metabolic ladder forcing the gene to remain active.

No, you are wrong. This is not a question of what it "may" be, we've found the genetic differences responsible in various populations.

Simplifying dramatically, the mechanism that controls whether the "lactose gene" "goes dormant" is another gene. The change to the control system is a genetic mutation.

Milk is also uniquely able to help adults add on and maintain muscle mass. Body builders even use the acronym GOMAD (gallon of milk a day). Using GOMAD, a strength coach can put 50 lbs of muscle onto a lanky kid in one year. There is no other way to do that without steroids.

Yogurt and cheese do not have the same effect.

Does the milk in a cappuccino count?

It's physiologically impossible to gain more than 2 pounds of muscle per month without using steroids. Your body is incapable of creating muscle at a faster rate. Half of that "50 lbs of muscle" (at the very least) is fat and water weight.

Well our paleolithic friends who developed tolerance wouldn't have had modern strength training to need to gain all that weight.

Brock (Lesner?) references body builders, many of them are on steroids.

But personally I know it's possible to gain roughly that amount without roids, not likely but possible.

Since muscles are bags of mostly water, this is tautologically true. But that's missing the point.

It's important to consider the context. GOMAD is typically prescribed to the 130 pound 15 year old. Moving a 130 pound guy who looks like a child to a 180 pound guy who looks like a man is a relatively easy transition around the time most people get into this sort of training. You don't need steroids for this sort of thing.

Taking a 205 pound athlete and making him a 255 pound powerhouse is much harder.

It's very possible, people do it, particularly those who have small muscles, have had large muscles before, young and are reasonably genetically gifted. While 50 pounds of pure muscles is unlikely 35 or so isn't. I agree people often forget that they almost always gain fat when they add muscle when the gains are that big. I don't think there is anyone who has gained 50 pounds in a year actually looked cut after the year. But taking a 120 pound guy and bring them to 155 in a year isn't physiologically impossible without steroids

There's also an element of perception. Take a 5'10" male at 130 pounds and 6% body-fat. Most people will think he looks sickly. Take the same 5'10" male at 180 pounds and 12% body-fat. Most people will think he looks athletic.

I think that's the source of "50 pounds of muscle" claim, even when there has been about 14 pounds of fat added.

Any deeper scientific reason than "Bodybuilders do it?"

Lactose tolerance is a classic example in the study of human biodiversity of how recent evolution in some human groups (but not in others) can have a large impact on economics and politics (i.e., conquest of land). The recent evolution of the sickle cell allele as a defense against the worst kind of malaria is another classic.

Of course, this is an exhaustive list.

Stay tuned ...

This is an extremely stupid analysis. My brother is lactose intolerant. Yet neither of my parents are. Nor am I. Apparently its a random thing, ALWAYS. Its not inherited. Its not a random mutation produced by evolution and then passed on. Its always random. There's a random change that you can be born tolerant or intolerant of lactose. It just happens. No inheritance--no evolution. Get a brain people. Quit grasping at straws to prove your false theory.

I, for one, welcome our randomly-mutated-in-every-generation-without-evolution lactose tolerant overlords.

random rey said, "Apparently its a random thing, ALWAYS".

Rey, you keep using that word, 'random'. I do not think it means what you think it means

Can't tell if serious...

It's a dominant. You only need one copy. So if each of two parents had one copy, some of their kids would have 1 copy and be lactose tolerant, some would have two and be lactose-tolerant, and some might have no copies and be lactose-intolerant.

I expect to hear a lot more people talking along this line in the future.

Ok, so you start with two pea plants, one produces green pods and one produces yellow pods....

"My brother is lactose intolerant. Yet neither of my parents are. Nor am I."

Hmm, does your brother look like your father, or perhaps he looks like the mailman?

There's a joke in here about the milkman somewhere, but I can't quite see the details.

Is there any reason to think lactose intolerance is conversely advantageous? If it's not helping (I'm not sure why it would be advantageous but there's bound to be a reason for it in the first place) then why should evolution care to preserve it if a mutation is available?

Evolution doesn't care about anything, ever. What on earth.

I apologize for use of personification. I apparently was not making my point well.

I'll try this - lactose intolerance may or may not have advantages. If it has no benefits then we're dealing with a situation where we should expect a mutuation that provides strong benefits to spread rapidly. Evolution doesn't necessarily find optimal solutions. Stephen Jay Gould's Panda's thumb is the line of thought here. It's not very good - but it gets the job done. Evolution works with what it's got (again personification - apologize again if this is not permitted in this forum). In the case of lactose intolerance a mutation bridges a gap and allows a rapid leap to a higher local maximum or minimum. At least that's the line of thought that prompted the initial post.

Lactose intolerance is advantageous if you don't consume lactose. Producing lactase costs more than not producing lactase. Humans quit consuming mother's milk after a few years, so there was no selective pressure to retain lactase production.

Muhry, good point. When I read this post I also recalled reading a book - sorry can't remember the name - of a British explorer who traveled w/ nomadic peoples in the deserts of Saudi Arabia (I think) - trying to find the source of desert locusts. Camel milk was one of their staples in their travels - and health of the camel was as or more important than health of the travelers. The Camel was their traveling food-source and difference of life/death in the desert. No need for refrigerator - but it was a traveling source of nutrition. They'd grab figs when they could - but those opportunities were rare. Not sure if this translates well to the overall move to lactose tolerance - but the milk's steady/dependable output might be very valuable to carry through periods of time when other food sources might be less reliable. Chicken/egg would be a similar model - but milk is even more easily portable.

Why first look at direct selection for an explanation? Why not drift. Or linkage. Or any other explanation that doesn't necessarily follow a pattern of evolution causing "advancements".

Because the trait has spread way too fast to be explained any other way. I know of a geneticist that doesn't believe that there has been strong selection on LCT variants, but he's an idiot.

The 10,000 B.C. date is somewhat misleading, even if it is possible that the mutation was present in very low frequencies by then as a neutral mutation in terms of selective fitess in that era (the margins of error around methods for dating the appearace of genetic mutations is huge). The reality is really more interesting.

Agriculture and the domestication of animals (other than dogs) arose in the Ferile Crescent around 8,000 B.C.E., with proto-farming of undomesticated plants and animals preceding this by as much as a couple of thousand years. Dairy farming probably arose a bit later than the use of domesticated animals including cattle. The oldest evidence of dairy farming in North Africa and Europe dates to 5,000 B.C.E., a thousand or two thousand years after the first evidence of any kind of farming or herding in these areas, with this development probably arriving somewhat earlier in the Fertile Crescent.

We know from dozens of ancient human DNA that the ability to drink milk as an adult was very rare in the first farmers and herders of Europe (who started to appear in Europe ca. 6,000 B.C.E.) who had origins in Fertile Crescent populations (and that it was likewise rare in the indigeneous European hunters and gatherers whom they demographically overwhelmed in all areas that was reasonably hospitable to their kind of agriculture).

This trait instead came to be common in Europe (again on basis of direct evidece of ancient human DNA samples) starting sometime in the copper age or early Bronze Age (ca. 3,500 B.C.E. to 2,500 B.C.E.) in connection with a subsequent wave of farmers and/or herders who made a major contribution to the European gene pool. Adult milk consumption was probably only one part of a package of genetic and cultural innovations (together with innovations like metal working) that allowed these second wave farmers and herders to gain a decisive advantage over the first farmers and herders of Europe. The expansion of this mutation, which reflects when it became important evolutionarily regardless of when this mutation first appeared in the gene pool, probably dates from around this time in Northern Europe and then migrates South.

Give the fact that the Basque (the last linguistic remnant of pre-Indo-European populations in Western Europe) have this mutation at the highest rates in Europe, while some neighboring linguistically Indo-European populations such as the Gascons have some of the lowest frequencies of this mutation in Europe, the mutation's expansion probably pre-dates the arrival of Indo-European linguistic populations in Western Europe (ca. 1,300 B.C.E. and later; Indo-European expansion happens earlier further to the east in Eurasia).

The overall processes involved echo the observations of economist Joseph Schumpeter in his 1939 book, "Business Cycles," that economic growth is driven largely by technological innovation (a welcome relief from the finance dominated theories of most contemporary macroeconomists), and as he observed in his 1942 book, "Capitalism, Socialism and Democracy," that the process by which technological innovation brings about economic growth is one of creative destruction in which the old order collapses in favor of a new one composed mostly of newcomers rather than through innovation by those who were the winners in the old order.

The notion that anyone would be surprised that this mutation would confer a major selective advantage is itself surprising. Obviously, it makes a huge difference in who survives bottlenecks of food scarcity.

"The notion that anyone would be surprised that this mutation would confer a major selective advantage is itself surprising. "


"Adults who cannot drink milk don’t seem to lose very much, particularly as they can still eat yogurt and cheese."

Wrong tense on the verb. This is true in modern times but until quite recently in most of Scandinavia and all of Ireland, raw cow's milk was the primary and the most reliable source of protein and fats. Being able to digest it usually meant the difference between suriviving and not surviving.


It was fun to read, but I was mildly put off by the overreach, equating Europe with "civilization" and ignoring two thirds of the civilized world that thrived without non-human milk for all recorded history. They were mentioned once in the third paragraph and then forgotten. The article becomes a bit more telling, perhaps not in the way the author intended, if one accurately replaces every generalization with "In Europe and the West ...(same generalization)". Some of the arguments become less convincing.

Example: "[In the West, but not everywhere else] We are still reeling from the change: Heart disease, diabetes, alcoholism, celiac disease, and perhaps even acne are direct results of the switch to agriculture." But why not link the ill effects to the consumption of dairy or to the lactase gene itself rather than blaming the switch to agriculture? There are many agricultural populations that have not been similarly reeling, and (coincidentally?) do not consume any dairy. The underlying assumption is clearly that grains are bad, whereas milk and meat are both good. Reading between the lines, I suspect the article was written by someone from the paleo diet persuasion speaking to a paleo audience. According to this theory, I infer that the author is from the paleo denomination that promotes dairy, and he's trying to change the minds of the paleo orthodoxy that rejects dairy on the grounds that it's not paleolithic. :)

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