Why DO human beings drink milk?

We’ve all seen the sensationalist posts on social media claiming that dairy products are simply not good for human beings – it’s unhealthy and causes more harm than good. But how true is this? If human beings have been consuming dairy for thousands of years you’d kind of assume that it must have some benefits. Surely it can’t really be the poison many claim it to be.

Of course if the dairy industry is to be believed, milk and other dairy products are absolutely critical to human health. Many health experts and even the medical profession seem to be of the same view; heck, we even had the CSIRO telling us recently that some Australians are – gasp! – moving away from dairy WITHOUT proper medical advice.


Hmmm…  That does seem a bit unlikely to me. A food that has been in the human diet for less than 10,000 years and to which nearly 2/3 of the global population is intolerant is THAT critical? I don’t know about you but I regard that suggestion with some suspicion.

Of course, dairy farmers are adamant this is the gospel truth. In fact, in conversation recently a dairy farmer made the claim that “several leading nutritionists attribute the fact that developed countries’ average age is around 80 is due to the fact modern homo sapiens drink cow’s milk”.

Now, I don’t think I’ve ever seen such an ambitious claim before, nor have I ever seen any peer reviewed research that says that. But then again, I am hardly an authority of the subject. I did a quick Google and did indeed uncover an article that referred to a 2009 study that argued that drinking milk can lessen the chances of dying from illnesses such as coronary heart disease (CHD) and stroke by up to 15-20%. It seems this study was some kind of meta-analysis rather than novel research, as the article refers to the “review (bringing) together published evidence from 324 studies of milk consumption as predictors of coronary heart disease (CHD), stroke and, diabetes”.


This seems to be rather similar to a recent study along the same lines which uncovered the same general result from a meta-analysis of current research.


I was not able to locate the original 2009 paper, but my guess is that these are largely the same papers given the involvement of the UK’s University of Reading in both. I don’t know how this conclusion bears up to critical scrutiny, but I do note substantial funding from the dairy industry in the more recent study.

By contrast, I found two recent papers that suggest that consumption of dairy products may contribute to increased mortality in some cases.

“High milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women. Given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended”.


“The role of dairy product consumption in mortality generally appeared to be neutral in men. In women, dairy fat intake was associated with slightly increased all-cause and IHD mortality. More research is warranted on a possible protective effect of fermented milk on stroke mortality”.


I won’t pretend this is any kind of exhaustive analysis of the research on my part, I merely use these examples to illustrate the confusion of evidence around just what benefit dairy might offer. Generally speaking it seems there are arguments for both benefits and risks, although I do note that many studies are, in my opinion, confounded by the fact that dairy industry funding is involved.

To be honest, I can’t reach any sound conclusion from the various articles and papers I’ve read. On the whole, dairy consumption in Australia might offer some benefits, particularly around protection from cardiovascular disease, yet it is definitely implicated in increased risks of some cancers. It just isn’t clear to me whether dairy is worthwhile purely in health terms and I am not at all convinced it confers any sort of benefits in terms of longevity.

So, what about all those memes on social media about the awful risks of dairy consumption – how it’s responsible for cancer and bone fractures and all sorts of ailments, or even that it’s full of blood and pus? Well, there’s clearly a grain of truth in most of these but I suggest there is rather a lot of exaggeration going on. Still, dairy consumption does seem to be not without risks.

What all of this does lead me to wonder about though, is exactly why it is that humans consume milk and other dairy products at all. After all, we are the only mammal that has adapted to drinking mother’s milk after weaning. How did this happen and what are the evolutionary drivers for this behaviour and what benefits can we expect from dairy consumption in a modern setting as a result. What I uncovered is quite remarkable, at least to me.

Here, in a relatively quick overview, is an explanation for human consumption of dairy products in a purely evolutionary context. Of course, my usual caveat – this is what I’ve found from my own research, interpreted in my own fashion. I may be quite wrong. But I also think I am not overtly misrepresenting the science. I welcome any comments, clarifications or rebuttals. Please note too that I am addressing the health benefits of dairy consumption in an evolutionary context – I am not addressing the ethical question of dairying in modern Australia.

Mammals express a gene that causes production of an enzyme called lactase that allows them to digest the lactose in mother’s milk until they are weaned. Once they are weaned, the gene “switches off”. After that, drinking milk leads to a variety of stomach/digestive issues. This has evolved because while milk is a great food for a baby, it is obviously too costly for adults to suckle from mothers. So adult mammals get their nutrition from environmental foods.

In human beings, we have evolved a genetic adaptation such that the gene doesn’t switch off. This means we can continue to digest lactose throughout life, and that is called lactase persistence (because the gene allows us to continue producing lactase into adulthood).

The really interesting thing is that this genetic change is quite recent and only arose between 5000 and 10000 years ago. It seems to have arisen several times in slightly different ways. The most common version appeared in Europe maybe 8000 years ago and is closely associated with the spread of farming and domestication of cattle.

Before this, people had been using milk from animals like goats and camels in Africa and the Middle East – in these conditions milk quickly soured so the typical foods eaten were yoghurt and cheese. In both cases, the fermentation process breaks down the lactose which makes it possible for people to eat such foods even with lactose intolerance.

The spread of farming into Europe meant that milk was able to keep for longer, but it was also unlikely to be consumed given the lactose intolerance thing. Eventually, somewhere or other (maybe near Turkey) someone had a gene mutation that turned on the lactase persistence gene. This probably happened more than once, but it needed some kind of opportune event for that mutation to spread.

Once it began to spread, selective pressures were of such high order that it spread quite quickly. Today we can see how that worked by looking at the frequency of this genetic change in populations. In some parts of Europe, up to 100% of the population have lactase persistence, while in others very few do. And of course there hasn’t been either enough time nor cultural changes for it to spread very far. As a result, most of the global population remained lactose intolerant until quite recently – eg native Americans, many Asian populations, a majority of Australian Aborigines etc.

The big question is why did humans develop this adaptation? The answer appears to be that no-one really knows. There are a few theories but further research is needed.

To understand this, we need to know a little about evolution. Evolution isn’t a directed process as such, nor does it have our best interests at heart. All it “cares” about is whether we produce more children. In other words, whatever happens, it is having more surviving offspring that makes the difference and fixes genetic change in populations. Regardless of how the change arose.

In the case of milk, it seems there is something about it that gave peoples in Europe an adaptive advantage. Some of the ideas relate to presence of calcium and Vitamin D but this is not highly regarded nowadays. It might be that it provides some kind of insurance against drought or famine, though quite why or how people would keep their cows alive in times of drought is a little hard to guess.

One very good possible explanation is that we ourselves created the selective pressures by our lifestyles. Nomadic hunter/gatherers tended to eat natural diets that were largely healthy, or they adapted to whatever foods were available (they had to, if they didn’t they would simply die off).

Once we began farming and settling down into large communities, neolithic farmers tended to develop poor health. In fact, agriculture has been described as one of the biggest mistakes in human history! I don’t know about that, but I get the point. It’s certainly one of the worst things that has ever happened as far as all the other animals and the environment are concerned…

Anyways, as settled farmers, neolithic peoples ate less diverse ranges of foods, increased the amount of animal flesh in their diet, and by being in large stable communities it was easier for disease to spread. In such a situation, it is possible that the higher nutritional value of cow’s milk made for a more constant nutritious food supply (for example, crops might fail, or there might be long periods between harvesting and so on).

So communities who dairy farmed had a sort of insurance policy against the very health risks they themselves had created.

What is very clear is that the lactase persistence gene follows the spread of dairy farming – where people farmed dairy cows, the people were (or became?) lactose tolerant…

Of course, this kind of adaptation to digesting lactose occurred elsewhere, for example in Africa, but there it was due to a slightly different mechanism and probably for different reasons. As all mammals produce milk for offspring, humans can probably get the benefit of milk from many different animal sources. The lactose tolerance thing applies to whatever source one makes use of. In other words, the adaptation isn’t about consuming dairy per se, it’s about being able to digest lactose.

So where does that leave us? Well, here is my summarised take on the whole picture.

Human beings can, and did, get all the nutrition they needed from natural sources without dairy, and indeed most of the world’s population still does. Until quite recently we had not evolved to consume dairy products at all. Like all other mammals, we evolved to wean off mother’s milk as we matured and thereafter eat from the natural environment. This appears to have been quite satisfactory in terms of survival, but again I will point out that survival doesn’t necessarily translate into a long, healthy life…

Lactase persistence is a genetic adaptation that must have offered some survival benefit such is the speed with which it spread throughout the population. A likely explanation for its strong selective pressure might be that it is an example of niche construction in evolution – that is, we probably created the conditions to encourage the spread of the genetic adaptation.

It is very likely therefore that the consumption of dairy is not specifically a dietary advantage at all times, rather it is more of a hedge against other environmental factors. Nonetheless, mother’s milk is a nutritionally sound food. This must be balanced against the clear point that evolutionarily speaking, no other animals consume milk past weaning, so nature has never had to ensure that milk confers health benefits over the long term for individuals. I suspect we have no idea how long term over-consumption of milk affects populations.

And that is one of the big risks in dairy. As a short term hedge strategy, it only has to provide sufficient nutrition for people and their offspring to survive and produce more offspring in difficult times. It doesn’t need to ensure a long life, and nor does it need to be consumed all the time. It might be that long term over-consumption of dairy brings with it health risks that are only seen at the far reaches of longevity, or in modern settings. As indeed current research seems to show.

Consider our neolithic farming communities. They would have eaten as they needed of things like animals, fruits, vegetables, perhaps fish, and dairy. Dairy may not have been a big part of their diet, certainly not to the extent we see in modern Australia, and in any case they didn’t have the kind of insights possible in modern health care and research. As they tended to have shorter lifespans, they would hardly have noticed whether dairy had any adverse long-term effects, though they would have noticed if dairy helped in tough times.

What has made the bigger difference in modern times as far as longevity goes is a range of factors such as better health care, less rigorous lifestyles, antibiotics and more generally available foods without the feast or famine kind of cycles. Dairy more than likely fitted in with that quite happily, and any possible risks would be masked by the generally improved health status of Western populations.

And really, it seems highly likely that moderate intakes of such forms of dairy as cheese and yoghurt are probably net beneficial. Milk itself is also likely to have some beneficial effect though here we are probably talking more about convenience – that is, it is easier to get certain nutrients (eg calcium) from dairy than to have to worry about maintaining a balanced diet complete with the right nutrition. In other words, milk consumption probably makes up for the typically poor Western diet.

If that were all there is to the story we might consider that dairy consumption in modern Australia is a health benefit. However the dairy industry encourages over-consumption of dairy products and so it seems likely to me that we are conducting a big experiment on our health by doing so. The results of that experiment might be the kinds of risks now being uncovered, such as increased risks of various cancers. As I noted above, perhaps over-consumption of dairy has health risks when viewed over the longer term.

The bottom line though seems to me to be that there is nothing in the story of dairy that would actually point to dairy being an essential element in the natural diet of a human being. I doubt very much that we have some improved longevity due to dairy – the best that could be said is that the inclusion of dairy in neolithic diets provided a protection against other environmental risk factors.

One curious possibility that occurs to me is that perhaps the same niche construction drivers exist today. Consider that as I observed above, the modern Western diet is generally acknowledged as rather poor. People eat the wrong foods, in particular processed foods, they eat far too much, and we have very sedentary lifestyles. Perhaps whatever benefits are claimed for dairy really only arise in the modern setting because its consumption helps to redress the balance against the same compromised health due to diet and density of stable populations that bedevilled neolithic farming communities.

And consider too the significant role that the livestock industry plays in encouraging people to partake of such poor diets. Could it be that the livestock industry is engaged in a circular feedback loop – compromise human health by encouraging an unhealthy diet/lifestyle and mask that through the consumption of dairy products?


Australia Day 2017

Soon here in Australia – on Thursday January 26 2017 – we will be celebrating Australia Day. This is a national public holiday, a day of family, friends and reflection. As the website “Australia Day” says:

“On Australia Day we come together as a nation to celebrate what’s great about Australia and being Australian. It’s the day to reflect on what we have achieved and what we can be proud of in our great nation. It’s the day for us to re-commit to making Australia an even better place for the future… On Australia Day, half of the nation’s population of 24 million attend either an organised community event, or get together with family and friends with the intention of celebrating our national day. Many more spend the public holiday relaxing with family and friends”.

Australians everywhere will mark this day by embracing those Aussie traditions of family, togetherness, mateship, of giving everyone a fair go.

And so it is especially sad that the Meat & Livestock Association has appropriated this day as the centrepiece for a campaign to encourage us to eat more meat. In particular, to eat more lambs. Somehow the idea has been born that it is the Australian way to sit down to a feast of young sheep.

As Sam Kekovich, the buffoonish Lambassador said this time last year:

“At the end of the day, Australia Day is about a bunch of people coming together around a barbecue, over some lamb, taking a deep breath, and treating people the way you’d like to be treated. Lamb just brings people together. All your family, all your mates. That’s really what Australia Day is about.”

Really? To enjoy what Australia day is all about we choose to ignore all of that stuff about a fair go, about treating others as we’d like to be treated, about making Australia a better place, and instead indulge in the not inconsiderable exercise of killing as many young animals as we possibly can, just for the pleasure of it.

Well, I dunno, I just can’t go along with that. Every year, we steal over 20 million young sheep from their mums and slaughter them for absolutely nothing more than a moment of gustatory pleasure. And the M&LA wants us to ignore what that really means just so we can line their pockets with more profits.

Surely it can’t be that this is all we care about, the sole measure for human behaviours – that it feels good or that it makes money? Why not extend our circle of compassion and say no to profits at the expense of lives, say no to pleasure when the price is pain and suffering. This year for Aussie Day, how good would it be if more of us chose to leave animals off the plate entirely?

It’s a nicer thing to do, and more in keeping with the Australia that we should want to be proud of. One where maybe it’s OK to care for others.

Now THAT would be a fair go.

PostScript:  How cool is this??? Dave Hughes tells us how it is

A thought about what ‘better’ means

I wrote about the matter of welfare policies for farmed animals being something of a red herring. In outlining my position on this matter, I responded to arguments put forward by Temple Grandin. I pointed out that Temple’s claims rest on the proposition that we MUST eat animals, a proposition I regard as flawed. It seems to me that while better welfare policies and practices do confer some improvements for the experiences of farmed animals, this is something of a salve to conscience that legitimises the very fact that we farm them with all the harm this entails.

The following post reblogged here from There’s An Elephant In The Room succinctly captures a similar view…

There's an Elephant in the Room blog

animal-1845413_960_720All of us are sentient individuals, the majority of whom have never been confined, never been tortured, never been mutilated deliberately and without anaesthesia, never been forcibly impregnated, never had our babies taken from us, never been hooked up to milk pumping machines or egg conveyors, never been starved and loaded onto trucks that take us to a place that smells of blood and fear, where we will hear the screams of our friends alongside the sounds of saws and machinery and know that our own death is coming.

With absolutely no personal experience of the horrors that we inflict on our sentient and desperate victims, who are we to decide how our ‘treatment’ of them while all this is happening, can be improved and better regulated? Yet this is exactly what we are presuming to do when we petition and protest for what we think are ‘better’ conditions in which…

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Pragmatic welfare policies for farmed animals – important, but is the very idea a red herring?

farm-welfare-bannerRecently I was sent a link to an article written by Temple Grandin in which she discusses the need for practical approaches to developing policies for animal welfare in livestock farming. Temple is an American professor of animal science at Colorado State University, world-renowned autism spokesperson and consultant to the livestock industry on animal behaviour.


I found this article quite interesting and agree with much that she says. However, I can’t help feeling that Temple has fallen into a trap that the vast majority of people fall into. That trap is quite simply the belief that human beings in modern societies such as the US, Europe and Australia MUST eat animals for health and nutrition. As a result, Temple’s ideas and philosophy are heavily influenced by that particular point of view. The question I would ask of her is whether she would reconsider her views were she to adopt the notion that we do NOT have to eat animals for health and nutrition. After all, it is a pretty well established fact now that humans can indeed live on a plant based diet AND that heavily meat leaning diets can pose risks to health.

Temple states early in this article that it is highly likely that farmed animals are conscious experiencing beings. If as Temple notes animals can suffer, and animals such as pigs and cows and sheep etc are intelligent, it seems to me to be very difficult to argue that we should kill them in large numbers without good reason. And the science is pretty clear on this – animals experience sensations such as pain, they have emotions, they can experience physical responses to stresses and negative as well as positive experiences and so on. In short, they are just like us in terms of the lived experience.

My proposition then is that when we know that humans don’t need to eat animals for sustenance and we also know that farmed animals are intelligent, experiencing beings that can suffer, surely it is the moral issue that becomes the deciding factor in whether or not we choose to eat them?

We believe ourselves to stand apart from other animals by virtue of our capacity to make reasoned choices and to practice moral behaviours. As far as I can see from both common sense grounds as well as observing the development of moral ideas over thousands of years, we should believe that our first duty is to do more good than harm. It’s why Jesus is claimed to have said “Do unto others as you would have them do unto you”.

Thus as moral agents we should have a charge of responsibility when it comes to dealing with intelligent, sentient and experiencing beings such as farmed animals. I suggest that when it comes to using animals for food and other products, we should do so as little as possible, only for the right reasons, and with the least suffering. In the modern livestock industry, we do the exact opposite. We do it as much as possible and seek to do more of it, we do it for all the wrong reasons, and we often cause far more suffering than need be.

Temple believes that we can ethically farm animals for food and that is probably true within the context I’ve outlined above, but I think a moral distinction also needs to be made when it comes to what we mean by “food”. As I’ve argued before, in Australia at least we have transformed eating into an entertainment. Much of our food consumption is for fun – Australians consume a lot of food simply for the pleasure it brings. Taste trumps everything.

There appear to be two opposing tensions here – on the one hand, as moral agents we should seek to limit harm to others as much as possible. If we must eat animals, then do so only as needed. Yet on the other hand, we have made eating a pleasure and a source of profit. The industry seeks to encourage people to eat as much as possible with no discrimination about what, how and when, or in what quantity.

Temple seems not to grasp this simple fact. When we turn the breeding and killing of other sentient beings into a mass production system to service the greed and gluttony of self-indulgence, I suggest we have well and truly crossed the moral divide. Temple isn’t participating in a thoughtful, welfare conscious process for feeding humans whilst limiting harm. She is in fact helping an industry that causes massive harm for little more than profits.

Simply put, our modern food industry isn’t a machine for good. It is a machine for bad. And that is the very basis for moral evaluation – morals are simply the distinction of good from bad. Which means that the modern food industry is immoral.

Temple goes on to attempt to establish some kind of gradient for moral value based on intelligence. Yet this seems to me to be rather arbitrary if not entirely self-indulgent – after all, the very yardstick for measurement is a human derived idea of “intelligence”. We establish the moral worth of animals according to an entirely human value system.

Why use intelligence? Intelligence really is neither here nor there. We have great intelligence and yet when we consider how we’ve applied it, we have done almost nothing of true worth. We have simply proven to be more fit in selective terms. No better than dinosaurs, and arguably far worse because in little more than one quarter of a million years we’ve brought the planet to brink of extinction. Dinosaurs ruled for several hundred million years without ruining the planet.

Given science tells us – as even Temple admits – that such creatures as cattle, pigs, sheep, chickens and perhaps fish appear to have the capacity to suffer, might this not be a more suitable measure of moral worth? After all, if a pig and a chicken can suffer equally, why discriminate because one performs better at human designed cognitive tests? I think this stance of Temple’s rests on solid ground pragmatically, but her choice of moral measurement seems weak and more designed to meet her own desire/need to eat animals while maintaining moral redemption. Simply put, she’s wrong and she knows it, but like most of us she will rationalise that away.

Finally, I’d like to highlight another weakness in Temple’s argument that I’ve previously touched upon. The old “nature versus farm” chestnut. This one suffers from a logical inequivalence.

Temple says “When animal issues are being discussed, people often forget that nature can be harsh. Predators kill other animals, and they may die a painful, lingering death. Storms and droughts can cause many wild animals to die. Much suffering occurs in the natural world”.

This is a misdirection. It matters not how animals might live in the wild because, as I’ve observed before, not one of these animals ever will, nor ever would have, existed in the wild. It’s like suggesting that harming a human being is fine, because worse harms have happened in some other time or place. One bears no relationship to, nor excusing role upon, the other. All that we can reasonably consider is the life and treatment of the farmed animal because that lies within our own scope of concern and effect. Not some unrelated circumstance.

Temple confirms she’s totally missed the point when she notes that “a flash of insight came into my mind. None of the cattle that were at this slaughter plant would have been born if people had not bred and raised them. They would never have lived at all. People forget that nature can be very harsh, and death in the wild is often more painful and stressful than death in a modern plant. Out on a western ranch, I saw a calf that had its hide ripped completely off on one side by coyotes. It was still alive and the rancher had to shoot it to put it out of its misery. If I had a choice, going to a well-run modern slaughter plant would be preferable to being ripped apart alive”.

This is a nonsense. A farmed animal’s entire life is at the whim of the farmer who caused it to be born. Whether it dies terribly through the predation of coyotes or “humanely” at the slaughterhouse after a short life, this lies squarely at the feet of the farmer. The choice isn’t between some awful natural death and some sweet benign “humane” death because there is no choice and no comparison.

Temple’s comment would be more correct had she said that her flash of insight showed her that all of the cattle being killed had no choice at all because the farmer gave them none. Whatever harm or death these animals suffered were directly caused by the farmer.

Temple seems to be arguing that the farmer has done a good by giving life to an animal that goes on to suffer. This is an empty argument. All we can ever do, in making moral assessments about lives lived, is examine the life that IS lived. And if the animal is a pig or a chicken in an intensive farm, or a lamb snatched from its mother to be killed for a taste, or a male calf killed because his cost outweighs his return, then it would have been better had that animal never lived in order to suffer. The farmer’s choice to give this animal life is not a good. Temple is wrong.

And that’s my feeling about this whole article. While I can see where Temple is coming from, and while I agree with many of her suggestions for how better to formulate pragmatic and more effective real world welfare policies, I think the basis for her argument is fatally flawed.

It is easy enough to see that the modern livestock farming industry does not have at heart the goal of feeding people for sustenance in the most responsible manner possible. In fact, it’s goal is to encourage more and more consumption for pleasure because that’s the only way to grow the industry and retain profitability. Like so much of modern consumerism, it’s a failed ideology.

Really, it’s a simple enough proposition. When we harm sentient beings, we as moral agents should have a charge of responsibility to ensure we do it as little as possible, for the right reasons, and with the least suffering. In the modern livestock industry, we do the exact opposite. We do it as much as possible and seek to do more of it, we do it for all the wrong reasons, and we often cause far more suffering than need be.

Plant-based alternatives are the better course for delivering as much of human sustenance, nutrition and pleasure as possible. We need to find ways to make that happen. If we must eat animals because there is some natural necessity in nutritional terms, then it should be as little as possible and only as needed. That would be the ethical approach.

As Temple herself says in closing, “People have the intellect to become good stewards of both the land and the animals, because they are aware that their actions can cause either suffering or destroy the environment”.

Perhaps we’d do well to take that advice far more seriously.