The Paleo Diet Is Not Based On Science

We still hear and read a lot about how a diet based on what our Stone Age ancestors ate may be a cure-all for modern ills. But can we really run the clock backwards and find the optimal way to eat? It's a largely impossible dream based on a set of fallacies about our ancestors.

Lamb picture from Shutterstock

There are a lot of guides and books on the palaeolithic diet, the origins of which have already been questioned.

It's all based on an idea that's been around for decades in anthropology and nutritional science; namely that we might ascribe many of the problems faced by modern society to the shift by our hunter-gatherer ancestors to farming roughly 10,000 years ago.

Many advocates of the palaeolithic diet even claim it's the only diet compatible with human genetics and contains all the nutrients our bodies apparently evolved to thrive on.

While it has a real appeal, when we dig a little deeper into the science behind it we find the prescription for a palaeolithic diet is little more than a fad and might be dangerous to our health.

Mismatched to the modern world

The basic argument goes something like this: over millions of years natural selection designed humans to live as hunter-gatherers, so we are genetically "mismatched" for the modern urbanised lifestyle, which is very different to how our pre-agricultural ancestors lived.

The idea that our genome isn't suited to our modern way of life began with a highly influential article by Eaton and Konner published in the New England Journal of Medicine in 1985.

Advocates of the palaeolithic diet, traceable back to Eaton and Konner's work, have uncritically assumed a gene-culture mismatch has led to an epidemic in "diseases of civilisation".

Humans are, it's argued, genetically hunter-gatherers and evolution has been unable to keep pace with the rapid cultural change experienced over the last 10,000 years.

These assumptions are difficult to test or even outright wrong.

What did our Stone Age ancestors eat?

Proponents of the palaeolithic diet mostly claim that science has a good understanding of what our hunter-gatherer ancestors ate.

Let me disavow you of this myth straight away — we don't — and the further back in time we go the less we know.

What we think we know is based on a mixture of ethnographic studies of recent (historical) foraging groups, reconstructions based on the archaeological and fossil records and more recently, genetic investigations.

We need to be careful because in many cases these historical foragers lived in "marginal" environments that were not of interest to farmers. Some represent people who were farmers but returned to a hunter-gatherer economy while others had a "mixed" economy based on wild-caught foods supplemented by bought (even manufactured) foods.

The archaeological and fossil records are strongly biased towards things that will preserve or fossilise and in places where they will remain buried and undisturbed for thousands of years.

What this all means is we know little about the plant foods and only a little bit more about some of the animals eaten by our Stone Age ancestors.

Many variations in Stone Age lifestyle

Life was tough in the Stone Age, with high infant and maternal mortality and short lifespans. Seasonal shortages in food would have meant that starvation was common and may have been an annual event.

People were very much at the mercy of the natural environment. During the Ice Age, massive climate changes would have resulted in regular dislocations of people and the extinction of whole tribes periodically.

Strict cultural rules would have made very clear the role played by individuals in society, and each group was different according to traditions and their natural environment.

This included gender-specific roles and even rules about what foods you could and couldn't eat, regardless of their nutritional content or availability.

For advocates of the palaeolithic lifestyle, life at this time is portrayed as a kind of biological paradise, with people living as evolution had designed them to: as genetically predetermined hunter-gatherers fit for their environment.

But when ethnographic records and archaeological sites are studied we find a great deal of variation in the diet and behaviour, including activity levels, of recent foragers.

Our ancestors — and even more recent hunter-gatherers in Australia — exploited foods as they became available each week and every season. They ate a vast range of foods throughout the year.

They were seasonably mobile to take advantage of this: recent foraging groups moved camps on average 16 times a year, but within a wide range of two to 60 times a year.

There seems to have been one universal, though: all people ate animal foods. How much depended on where on the planet you lived: rainforests provided few mammal resources, while the arctic region provided very little else.

Studies show on average about 40% of their diet comprised hunted foods, excluding foods gathered or fished. If we add fishing, it rises to 60%.

Even among arctic people such the as Inuit whose diet was entirely animal foods at certain times, geneticists have failed to find any mutations enhancing people's capacity to survive on such an extreme diet.

Research from anthropology, nutritional science, genetics and even psychology now also shows that our food preferences are partly determined in utero and are mostly established during childhood from cultural preferences within our environment.

The picture is rapidly emerging that genetics play a pretty minor role in determining the specifics of our diet. Our physical and cultural environment mostly determines what we eat.

Evolution didn't end at the Stone Age

One of the central themes in any palaeolithic diet is to draw on the arguments that our bodies have not evolved much over the past 10,000 years to adapt to agriculture-based foods sources. This is nonsense.

There is now abundant evidence for widespread genetic change that occurred during the Neolithic or with the beginnings of agriculture.

Large-scale genomic studies have found that more than 70% of protein coding gene variants and around 90% of disease causing variants in living people whose ancestors were agriculturalists arose in the past 5,000 years or so.

Textbook examples include genes associated with lactose tolerance, starch digestion, alcohol metabolism, detoxification of plant food compounds and the metabolism of protein and carbohydrates: all mutations associated with a change in diet.

The regular handling of domesticated animals, and crowded living conditions that eventually exposed people to disease-bearing insects and rodents, led to an assault on our immune system.

It has even been suggested that the light hair, eye and skin colour seen in Europeans may have resulted from a diet poor in vitamin D among early farmers, and the need to produce more of it through increased UV light exposure and absorption.

So again, extensive evidence has emerged that humans have evolved significantly since the Stone Age and continue to do so, despite some uninformed commentators still questioning whether evolution in humans has stalled.

A difficult choice

In the end, the choices we make about what to eat should be based on good science, not some fantasy about a lost Stone Age paradise.

In other words, like other areas of preventative medicine, our diet and lifestyle choices should be based on scientific evidence not the latest, and perhaps even harmful, commercial fad.

If there is one clear message from ethnographic studies of recent hunter-gatherers it's that variation — in lifestyle and diet — was the norm.

There is no single lifestyle or diet that fits all people today or in the past, let alone the genome of our whole species.The Conversation

Darren Curnoe is human evolution specialist at UNSW Australia. He receives funding from the Australian Research Council.

This article was originally published on The Conversation. Read the original article.


Comments

    I presume though Darren, you are not suggesting that eating "real food", i.e. food that has just been prepared from fresh (and hopefully as chemical free as one can get it) ingredients is an unsound idea.

    Although I am pro paleo - or more correctly "pro real food", I thought this was a great article. Thanks for the references.

      I'm pro imaginary food. The power of my mind makes the blueberry pie real enough for my body.

      It's kind of like Breatharianism only more scientific.

        This reminds me of the food fight scene in "Hook".

    You are choosing to ignore the fact that people have only been consuming flour from grass seeds for 10,000 years. Man evolved eating meat, berries and tubers. Cows eat grass. People should keep clear of it and consume it at their peril.

      And you're choosing to ignore the entire paragraph about what we know about evolution over those 10,000 years. Always pays to read before commenting.

    Interesting article thanks. You could also argue that the diet with the best health outcomes is most likely the one we are best adapted too. Although we are quite remarkable in the range of foods we are able to survive on, the common message (to me at least) coming from nutrition research is generally the less processed and more plant based the better. For example, the very interesting video below looks at common diseases in Americans and Ugandans and finds that many are almost non-existent in the plant-based Ugandan diet of the 50's. http://nutritionfacts.org/video/one-in-a-thousand-ending-the-heart-disease-epidemic/

      You still need meat and/or fish too though, ie. Japan and the Arctic diets (Although those are at the extreme side).

    So we need to base our diet on Science - and what have we been following to date and look where we ended up health wise. Wake up & realize what's really going on with our health & avoid carbs if you want to be healthy.

      Oh you mean the same science that has now enabled us to have an average life expectancy of 67, whereas 100 years ago it was about 30? That science is soooo unhealthy!

        I'm pretty sure the discovery of penicillin is the main contributor to that statistic, not diet as such.

    As Enzo said.. "Based on good science".. What's that, the same good science that has given us diabetes spiralling out of control, adhd in kids going through the roof, a massive increase in autoimmune conditions... And the list goes on! Oh, and is that the same good science that came up with GM crops, high fructose corn syrup, margarine and added msg? Gotta love that " good science" stuff...

      Oh, you must have science confused with advertising, rampant consumerism, increased opportunities for sedentary leisure and unregulated markets.
      Good science gave us the computer that you"re typing on. Better go on a Paleo-tech diet too perhaps.

    I think the real take-away from this is: Eat a variety of foods. Most doctors and nutritionists recommend it. I know of some kids who will only eat McDonalds chicken nuggets, which has to be an environmental factor, and disastrous in the long term. Limiting the foods you eat to just 'Stone Age' cuisine takes away some delicious food stuffs that are healthy in moderation. A life without pasta just wouldn't be worth living.

    Jamie Oliver has done some excellent work in food education and helping people develop the skills to cook food from scratch. I made my kids watch his Youtube video on knife skills before they started helping me in the kitchen. http://youtu.be/yJ44SxiemMs

    I don't really care what people think is healthy and isn't, but people that think they are superior because of the things they do and don't eat can just get lost.
    In the end, it matters what joy you get from your life, not how long you managed to stave off death.

    I like paleo because it tells me to put away the Weet-Bix and toast for breakfast and instead cook up some bacon or sausage!
    That being said, it is definitely silly to think that our bodies suit some idealistic past, and that that is the only way to eat. But the basic idea behind paleo (that we should eat what is natural for our species) still warrants some attention. Less processed foods is always going to be a good thing. And even though a lot of what our ancestors ate doesn’t exist today (at least outside of domesticated forms), sticking as close as we can to nature is probably smart advice. Whether that means we should stay away from grains, I don’t know; I’ll wait to see the evidence.

    As a scientist, everytime I read discussions on this, its quite annoying. No scientist has ever said eating natural is bad, no scientist has ever said reduced consumption of processed foods is bad. In fact, most food scientists and nutritionalists have said that a diet high in fresh foods, fruits and vegetables and lower in carb intake (in fact lower caloric intake overall) is good.

    The issue at hand here is none of those facts. It is the issue with Paleo diet, and just about every other diet on the market. These are written by people who take fundamentally sound principles, interpret them literally without careful consideration of variables and take it to the extremes. In the end you get a "one-size fits all" formula that, lo and behold, FAILS! The reason non of these diets cause any noticeable damage is because a combination of your body adapting to the change (and your fad diet disappearing in a few years..) and the hard work of modern medicine.

    And for all those who thinks their ancestor was healthier, if you're over the age of 30, chances are your ancestor was already dead.

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