Sometime around 2002 I began collecting and collating research papers on human evolution. This was initiated due to my interest in claims we ought to be exercising according to how our distant ancestors evolved and adapted. My primary interest was in biomechanics, but as a physiologist I was also interested in nutrition, and the research on our Palaeolithic ancestors often referred to the links between our eating habits and our physical evolution.

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As rather interesting apes, and in contrast to the wishful thinking of some vegetarians, we did not evolve from vegetarian primates. In contrast to the wishful thinking of just about everyone, we did evolve from insectivorous primates. That is, the primates subsisted on fruits and other plant source foods, with some proteins, fats and minerals from insects.  At some point we would have increased our meat intake, perhaps by hunting other primates and even via cannibalism, as has been observed in modern apes. Ultimately, we adjusted from a diet rich in plant source foods and insects, to one that incorporated greater amounts of meat, and was never exclusively plant or animal based (at least not for extended periods of time).

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I enjoyed researching the origins of our diet and evolution, then writing it up for my book Human Evolution, Diet and Health: The Case for Palaeolithic Nutrition. Broadly, the book discussed the changes in our guts, brains and the development of tools, and how these three coincided with improvements in diet. We increased the quality of our diets by obtaining more easily digested foods, so fibrous plant foods were replaced by higher quality fruits. Meats rich in healthy oils and proteins allowed us to obtain more energy, and this total increase in energy intake, combined with a reduced need for processing, allowed our guts to shrink. Many of the health problems we now face can be attributed to poor diet and exercise habits, and an understanding of how we evolved helps to highlight how we do not flourish on processed foods and sedentary lifestyles.

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Although the interest in Palaeolithic nutrition has sparked the publication of many books and articles, the message from the original literature has not been viewed by all authors.  In fact, the lessons from the research on evolutionary biology have been ignored entirely by some who recommend 'The Palaeo Diet'. This article was written so I could redress four common myths associated with The Palaeo Diet.

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1.  Anything Unprocessed is Palaeo

 

Our guts adapted as our dietary habits changed, and this occurred in the jungles of Africa. From a diet based on fruits and insects, we increased our intake of muscle and organ meats. This has led some interpreters of Palaeolithic nutrition to assume that any food that has not been processed is Palaeo.  This cannot be true, as it is specifically the foods available in African jungles, and later the savannahs, that were actually consumed by our ancestors, and so were adapted to. Foods available in Europe, Asia, Australasia and the Americas - if not available in Africa between 50,000 and 2 million years ago, cannot possibly be classified as Palaeo.

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Even foods that were available in Africa were not necessarily consumed by our Palaeolithic ancestors, or consumed sufficiently to lead to digestive adaptations that could have survived until now (gut lengths, enzymes and bacteria).  Our only indications come from inferences from non-human apes in Africa, such as bonobos and chimpanzees, and evidence from bone remains from Palaeolithic burial sites. The bone remains could be the animals consumed and the stone tool cut marks to demonstrate they were processed by ancient humans, for example. Alternatively, Palaeolithic human bones and teeth contain chemicals that can be matched to the foods we would have obtained them from.

 

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2.  Bacon and Salami

As discussed, it is not appropriate to simply assume that any unprocessed food qualifies as 'Palaeo', and in reality we would have a hard time determining precisely what fruits, insects and invertebrates we regularly consumed. Meat is a little easier, because we have some evidence in the form of stone tool cut marks, and from weapons, on preserved bones. The ancestors of modern antelopes and wildebeests were fair game, as it were, as were larger mammals such as woolly mammoths.

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There is even indirect evidence we were consuming predators as much as 2 million years ago, such as the sabre-tooth cats, or similar. This comes from the remains of a woman who had died following exposure to very high concentrations of vitamin A. This is something that would have required ingestion of the liver from a predator, as only carnivores accumulate such high vitamin A concentrations. Whether consumption of a predator occurred on this occasion following a deliberate hunt, or else following a lucky scavenge, cannot be determined.

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So, we were certainly enjoying a good mix of plant and animal source foods.  Stone tool cut marks have revealed we targeted the bone marrow and brains of carcasses, whether we had hunted the animal or scavenged it. There is evidence on both sides for this, with some bones showing stone tool cuts overlaying the tooth cuts from other predators (showing we scavenged the carcass), and other bones showing the reverse (so we discarded the bones after removing the meat). Our access to bone marrow and brain fits with the high amounts of omega-three fatty acids that are required for our good health, with marrow and brain being good sources of these.

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If we were to describe a truly Palaeolithic diet from Africa from the past 50,000 to 2 million years ago, we would be describing a diet rich in fruits and other plant source foods, and plenty of raw meat (evidence for the use of fires to cook meat does not come until relatively recently). Ingesting raw meat would have ensured the omega-three oils remained in excellent condition to be utilised, as oils become damaged once heated.

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Unfortunately, many of the people who promote a 'Palaeo Diet' do not understand this, and are not familiar with the primary sources of research on the subject (the journal Evolutionary Anthropology, for example, is a useful journal for primary research).  Hence, it has been assumed that any meat product can be included in the Palaeo Diet, regardless of the type of animal, type of meat and level of processing.

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Our Palaeolithic ancestors consumed raw meat, particularly the raw brains, bone marrow and organ meats of wild African animals, such as the ancestors of modern antelopes and wildebeest, woolly mammoths, and so on. They did not consume cooked meats until relatively recently, and they did not farm animals - farming determines the change from the Old Stone (Palaeolithic) Age to the New Stone (Neolithic) Age. They did not have access to modern pigs or pork products, farmed cattle, chickens or any other modern, farmed meats. The ratios of the different fats in the meats were different, the amount of organ meat consumed was different, and the meats were consumed raw rather than cooked.

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We can deduce that our ancestors probably did not suffer with type 2 diabetes mellitus, that cancers were fewer, that heart disease was mostly absent and so on.  That our ancestors only lived a few decades is a myth, unsupported by evidence - they were active throughout life and had an excellent diet. Where our modern diets let us down is through the inclusion of processed plant foods (cereal grains), the inclusion of dairy products, consuming minimal organ meats in favour of muscle meat, and having that meat altered through agriculture then prepared through heating.

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The chemical preservation of meats and fish, such as via smoking the meat and/or the inclusion of nitrates and/or sulphites, has been associated with increased risks of cancer, particularly colorectal cancer. Nitrates exist in nature, but typically in vegetables where there are chemicals present that protect against the harmful potential of nitrates. Nitrates also exist in tap water, not least as a by-product of chemical fertilizers used in farming, which run into rivers and end up in the water supply. These tend to be a minimal contribution though to overall intake, and protection is given by a reasonable intake of vegetables.

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Consuming high amounts of nitrates and other preservatives is not recommended, although an occasional intake is very unlikely to do harm.  Nitrates are banned from use as a preservative in most foods, but meats remain an exception. Preservative-rich food products, such as bacon and salami, are certainly not 'Palaeo' foods, and it is a mistake to suppose they are healthy.   Occasional inclusion will do no real harm because the body can protect itself, but continual exposure increases the risk of a negative consequence. This is true for most of the foods we might consider unhealthy.

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3.  Low Carb

Another popular misconception is that a diet approximating that of our Palaeolithic ancestors should be low in carbohydrates. We evolved from primates that consumed mostly plant-source foods, which are almost entirely carbohydrate, and with the inclusion of small amounts of insects. By the time we began using stone tools the plant foods we ate would have been of high quality (fruits rather than fibrous vegetation), and rich in carbohydrates, vitamins and other phytonutrients.

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How much meat we consumed is hard to judge, as we would have developed from opportunistic scavengers to excellent hunters. Our best Palaeolithic modelling has led us to suppose that adult males would have hunted whilst the females and adolescents gathered fruits and perhaps tubers.  The older members of the group would have remained at a central camp to care for the young.

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Although the amount of plant and animal sourced foods would have fluctuated on a day-to-day, and perhaps week-to-week basis, there would have been some uniformity. It has been suggested that our meat intake would have varied somewhere between 60% and 70% of our total daily diet, with the remaining 30% to 40% coming from plant foods. That would give us an approximately equal spread of each of the macronutrients - a little over 30% each for carbohydrates, proteins and fats. So, if anybody wishes to tout benefits of a low-carbohydrate diet, they will need to find a model not based on the diets of our Palaeolithic ancestors.

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4.  We Should Follow a Palaeo Diet

That the diet of our Palaeolithic ancestors was healthier than the typical westernised diet is beyond question in my mind. I consider that a modern equivalent - or the closest thing approaching it - would improve the health of many people, reducing incidences of disease and ill-health, promoting wellness and helping people achieve a favourable body composition. I would be reluctant to call any such diet model a Palaeo diet though, because nowadays we do not have access to the wild fruits of ancient African jungles, nor do we have access to the wild animals that lived at that time. We have all moved on. Wild meats are healthier, on the whole, than farmed meats, but would we want to consume only raw meats, favouring the brain and bone marrow above other organs and muscle meat? Unless the animal was our prey in Africa between 50,000 and 2 million years ago, however healthy it might be, it cannot be classified as 'Palaeo'.

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For a diet to be successful it has to be something that people are happy with, in every sense. Eating something for the enjoyment of it, rather than because it fits within the constraints of the diet, ought to be fine as long as it is the exception - one of those things we do for the simple enjoyment of it rather than because we want to govern ourselves with unbreakable rules (or consider ourselves a failure should we transgress).

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A Palaeolithic Diet does not exist, and nobody has had a Palaeo Diet for tens of thousands of years, and then only in Africa. The fruits and animals our own ancestors feasted upon are now extinct.  Their descendants evolved into new species, just as Homo erectus has been replaced by Homo sapiens. The fruits we eat contain fewer seeds, less fibre and less pulp than their ancient equivalents, but mostly of course they are entirely different species. The animals we consume have had their muscle structure altered to contain more fat and of a different type to that of the ancient, wild animals.

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To aim for a Palaeo Diet is an impossibility, for even if we were to up sticks and return to Africa, Africa and its jungles and species have changed too much. It would be futile and thus the idea of a Palaeo Diet is, unfortunately, absurd.  What we can aim for though is to use the lessons from that diet and lifestyle, and apply them as much as we can to the actual foods we have available to us now. We can adopt a natural diet, free from preserved and processed foods, and foods unnatural to us (in terms of what we can efficiently digest and utilise). I do not think this needs a name though - I think it is sufficient, when asked, to simply state that 'I aim to eat well'.

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For a deeper understanding of our evolutionary past, I wrote:

Human Evolution, Diet and Health: The Case for Palaeolithic Nutrition

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For my interpretation of a healthy, modern-day equivalent, I wrote:

Our Natural Diet: Optimal Nutrition for Health, Looks and Life.

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