Human Evolution, Diet and Health:
The Case for Palaeolithic Nutrition
The concept of Darwinian medicine is not a new one. Yet until recently there has been little interest in how this might be applied to diet and nutrition. The relationships between modern diet, modern disease and obesity are astonishing. Our most prevalent and devastating diseases are affected by what we eat, and the basis of effective treatment and prevention can be found in the diets of our Palaeolithic ancestors.
In Human Evolution, Diet and Health, Mark Hines examines the relationships in exquisite detail, showing again and again how modern diets can have harmful consequences for the human body. In this antagonism between our genotype and its environment, disease and obesity are not only more likely, but are practically foregone conclusions. The resolution of this conflict, we find, begins with the understanding of our pasts. Humankind's cradle in Palaeolithic Africa was where our genotype evolved, and the modern world is where it must now survive. The findings of this book have far-reaching implications for our future health, well-being, and medicine.
Human Evolution, Diet and Health is an informative text, rather than a prescriptive one. It has been written in the style of a popular science book, with the intention of promoting a deeper understanding of how the body works, how it has evolved, and how it deals with the various foods that we eat. Having read the book, the reader should not simply have an improved perspective of which foods might be considered good or bad, but they should have a good working knowledge of why the body responds to particular types of foods in the way that it does.
Human Evolution, Diet and Health is available to buy online at Amazon and Waterstone's.
Excerpts from the book:
Our Hunter-Gatherer Mothers and Fathers
"The most important and urgent problems of the technology of today are no longer the satisfactions of the primary needs or archetypal wishes, but the reparation of the evils and damages by the technology of yesterday"
The Palaeolithic began with the emergence of the Homo lineage some 2.5 million years or so ago, and the stone tools associated with our ancestors' fossils from that time. The Palaeolithic came to an end with the advent of agriculture and the start of the Neolithic, from around 10,000 years ago.
Up until approximately 500 generations ago, amounting to more than 99 percent of human history, all that our pre-agricultural ancestors consumed were wild meats, fish, insects, eggs, wild fruits and berries, wild vegetables and nuts, and all foraged from their natural environment. Their diet contained no agricultural grains or processed foods, was low in seeds and beans, devoid of dairy foods, margarines and refined sugars, and was low in sodium. Their diet was high in fibre, lean animal protein, monounsaturated fats, polyunsaturated fats (specifically the omega-three fatty acids), and contained plenty of vitamins, minerals, phytochemicals and antioxidants. Part of the reason that their diet was so healthy by comparison to ours was not simply that it consisted of an abundance of fresh meats, fruits and vegetables. The key was variety. We require about fifty essential nutrients for proper growth, metabolic function and cellular repair. As a consequence of our dramatic change in eating habits, it should be little surprise that researchers have concluded that we are maladapted to diets of domesticated and processed plant foods.
Nowadays it would be virtually impossible to adopt precisely this type of diet again, partly because of resources, partly because of the necessities of our westernised lifestyles, and partly because we cannot know 'precisely' which foods our particular ancestors consumed out of the thousands of plant and animal species available. What is important to note, quite significantly, is that less westernised groups and modern-day hunter-gatherers are largely free from chronic degenerative diseases and biomarkers of illness (such as rising blood pressure with age, increasing body fat, and insulin resistance). Resulting from our growing awareness of this fact, a number of doctors and nutritionists are beginning to advocate a diet more closely matched to that of our Palaeolithic ancestors.
A Natural History of Meat Eating
Meat eating itself occurs in both humans and the apes, although the sources of meat can be vastly different. If we eat meat, and our closest relatives the chimpanzees eat meat, then it is highly likely that so did our common ancestor in Africa. This would be the case even if we did not have evidence from teeth, tools, animal remains, stable isotope data, and so on. Chimpanzees consume an estimated 10 to 40 grams of meat per chimp per day, as opposed to we humans who consume between 270 to 1,400 grams per person per day. Amongst the chimpanzees, it takes many years to learn successful hunting techniques, with the older males being far more likely than the younger ones to ambush prey. Similarly, it is the older chimp males that perform the most complicated manoeuvres during the hunt, and that are best able to predict the escape routes of their prey. It is thought that the greater levels of cognitive processing required to learn these skills, are associated with the greater encephalisation of chimpanzees compared with monkeys, and hence the greater inclusion of hunting in their dietary behaviour.
It is the employment of hunting as a dietary strategy by humans, chimpanzees, baboons and some other anthropoids, which leads to the conclusion that hunting goes back a long time in our evolutionary past. Because of the time commitment required to care and carry the young, combined with the learning period required to become an effective hunter, neither human or other primate females would find hunting profitable. Hence, it is the human and chimpanzee males that are responsible for hunting. The meat obtained is then widely shared throughout each group.
When the ecosystem changed between 2 and 1.8 million years ago, the number of grazing animals in the newly forming savannahs would have increased upon the East African landscape. This would have led our human ancestors, who were already eating meat, to capitalise upon and exploit these new opportunities. Evidence is growing that early humans capitalised on the carcasses left by other carnivores, and in some cases they may have worked as a team to force carnivores away from their kills. Homo habilis, although only the size of the average ten-year-old, were known to have scavenged meat from the kills of sabre-toothed cats. The sabre-toothed cats had evolved such long teeth because they made them effective killers of large herbivores. In fact, the diminutive H. habilis would have been too small for the cats to attack, because their teeth were too big and too fragile, and their jaws too weak. The risk of breaking their teeth would have been too great, and as a consequence our ancestors were unlikely to have been hunted by them. Further, microanalysis of herbivore bone remains has revealed cut marks made by stone tools, which overlay teeth marks left from sabre-tooths. Thus, the cats made the kill, but it was human ancestors that polished off the remains.
Further evidence comes from the archaeological record of Homo ergaster. This is the species associated with the development of more advanced stone tools along with the first major hunting and gathering economy. Meat eating itself most likely goes back beyond the australopithecines, at least to some degree, but with Homo ergaster there was a significant shift in the amount consumed. A brief examination of the dietary behaviour of extant great apes also brings us to this same conclusion, that meat eating was a key and ancient aspect of our past. With the evolution of Homo ergaster approximately two million years ago, came a new reliance on meat as an integral part of the human diet.
Although some might argue that underground storage organs (USOs), such as tubers and rootstocks were being increasingly incorporated at this time, in most cases fire would have been necessary to obtain the nutrients from these foods. As controlled fire occurred much later on in human evolution, it was meat consumption that increased first, with USOs being incorporated later on, and to a lesser degree. The evidence from stone tools, the knowledge that carbohydrate-rich energy sources were not available, and the comparisons to extant great apes, all suggest how important meat eating was to our human ancestors in Africa, at least to significant degrees above that of their predecessors and non-human contemporaries. Carbohydrates would have been important for contributing to energy requirements, and because carbohydrates are in any case essential for good health, they would still have been an essential part of the diet. The newly developing reliance on meat fats and proteins, however, would have supplied greater quantities and a better quality of amino acids and other essential micronutrients.
Animal carcasses would have been acquired through both direct hunting and from scavenging, including driving other hunters and scavengers away from carcasses. Furthermore, the bone evidence shows that some animals would have been butchered at the site of the kill, and then transported back to the home base, presumably to be shared with the other members of the group and for greater security. Smaller animals would have been carried back whole, so the technology to butcher larger animals simply meant a greater ease of provisioning a home base. Evidence from this is found in bone refuse occurring in apparently domestic human sites dating back to almost two million years ago, and some possibly older still.
The development of new stone tool technologies initiated a feedback-loop with our growing brains. As the tools improved our ability to kill larger prey, and then to better access the meat, marrow and other tissues of the animals, so we became more efficient and better skilled in hunting and developing more tools. New technologies of stone tools emerged, such as that of the Acheulean industry of 1.6-1.4 million years ago, which allowed humans to better process these animal and plant materials. Evidence from this period suggests that more animal foods were available than could be consumed in one sitting. It was during this period of mass meat exploitation and cultural revolution, in which the final significant episode of encephalisation occurred, from which modern humans are the result.
The importance of meat in the development of the brain is twofold, both because of the increased caloric density of meat compared with plant foods, and in the type of fats then available to us in greater quantities. Again, access to the best animal fats from marrow and brain tissue required an adaptation of the early tool kit, which in turn stimulated our inventiveness and ingenuity in association with our increasing brain size. Furthermore, the energetic costs for pregnant mothers, with larger-brained foetuses than those of our predecessors, also meant that meat eating was important in providing the necessary calories.
This greater reliance on meat allowed for greater year-round provision of calories and nutrition, which may then have led to shorter birth spacings, and changes in the number of dependent youngsters within the groups, cared for by the elders as well as the parents. This may have further contributed to the cultural revolution, and then the expansion of our species and its contemporaries outside of Africa.
As mankind left its cradle in Africa and migrated across the globe, the changing of the seasons in more northern latitudes would have had a profound effect on food resources. Plant foods would have become less abundant because of these seasonal changes, and would therefore represent a less reliable source of nutrition.
Our success as a species outside of Africa hinged upon our ability to use animal foods for survival. This was not just true of our own species, but for other sibling human species as well (H. neanderthalensis, H. heidelbergensis, H. ergaster, H erectus, and the most recent addition of H. floresiensis, as key examples). Evidence for this shift in dietary behaviour comes from archaeological sites of these humans that contained a super-abundance of animal remains along with evidence of hunting tools. This increase in reliance on animal foods coincides with the absence of evidence of the use of plant foods (which is not to say that they could not have been included in the diet at all, but simply that not enough was included to leave any evidence, and no tools used in the preparation of plant foods have been found). It would be wrong to assume that the absence of evidence is the same as evidence of absence: we do not know what discoveries may yet be made. However, in this context, the super-abundance of animal remains and absolutely no indication whatsoever of plant remains, does give substantial evidence to the notion that the European humans were obtaining most, if indeed not all, of their energy and nutrition from the available animals.
Another important shift in behaviour that coincides with this is that of the family or group. In Africa, there was an efficient division of labour throughout all members of the group, but in Europe this would not have been the case for much of the year. With fewer plant resources available the women and juveniles would not have been able to gather in the same way as their African ancestors. With the abundance of animals being brought back by the men, it is perhaps more likely that all the other members of the group concentrated on teaching the young, on preparing the meals, and on maintaining and developing the home environment, including provision of clothing, bone tools, and maintenance of the fire. These factors were even more important in the colder climates of the north. Women would have been able to wean their young for a longer period before the necessity to move them onto solid foods. This greater attention to their young for a longer period, may have contributed to our eventual success as a species.
A key development regarding our increased reliance on animals for survival was not just the high quantity of animal kills, but also the size of the animals. A site in Boxgrove, in the South of England from 500,000 years ago, has a large number of Acheulian hand axes and remains of rhinoceroses, horses, and other faunal remains, the bones of which have clear cut marks on them. This is just one of a number of sites from this period and up to 300,000 years ago across Europe, which exhibit similar findings. This period, the Middle Palaeolithic, was one preceding the migration of modern humans from Africa. Hence, this evidence concerns the behaviour of our contemporaries, who migrated out of Africa and across Europe before our own direct ancestors.
Ever since the emergence of our lineage in Africa, meat consumption has increased in conjunction with our increasing technology and our migration across the globe. The results of stable isotope data have shown that the protein in Late Palaeolithic humans and their contemporaries came mainly from animal sources, and of those it was most likely to have been large herbivores that made up the diet. This evidence comes from analysis of groups of modern humans and Neanderthals from between 100,000 and 13,000 years ago (analysis following 30,000 years ago would have been exclusively of our own species, as the Neanderthals were believed to have become extinct at around this time). This is a matter of common sense, in that although one large animal may be equivalent to the combined weight of many small animals, it is far more energy-efficient to make only one kill. Additionally, larger species generally have a greater percentage of body fat, and so their total energy yield on a weight-by-weight basis would be greater.
Studies of the Europeans during the Palaeolithic show that their diet was indistinguishable from those of top-level carnivores, such as arctic foxes and wolves. As humans, we have a limited ability to synthesise taurine from other amino acids. By adopting a diet high in animal proteins (which would have included taurine), there would have been no selective pressures for us to synthesise the amino acid from plant foods.
One of the key differences between the protein sources for Neanderthals, and for modern humans of the last 30,000-20,000 years, is that our protein came from a more varied range of foods than for the Neanderthals. Specifically, we were incorporating aquatic foods in our diet. This is particularly important when we consider that Neanderthals, along with all of our other contemporaries, were extinct by around 30,000 years ago. Whether or not this was down to food choices and dietary initiative on our part, or pure territoriality against the Neanderthals which prevented them from accessing waterfronts, is not currently known.
Interestingly, this dietary shift towards aquatic resources became far more extreme much later on (around 10,000-5,000 years ago, depending on the area). Evidence of freshwater fish consumption, such as from isotope studies of humans living in the Danube gorges of South-eastern Europe, is supported by the archaeological evidence of fishing equipment and large numbers of fish bones. Further, in coastal regions of Denmark and England, isotope evidence suggests that marine fish were the primary source of protein.
During the Middle and Late Pleistocene, the range of humans extended into cold-temperature and sub-Arctic regions. This would have almost certainly led to the diet of such populations being almost exclusively meat-based. This is important to bear in mind as many pregnant women feel an aversion to meat. Whether or not this is a modern phenomenon, associated with the poorer quality of meat available as a result of high-intensity farming practices, cannot be known for sure. It is certainly difficult to imagine how modern hunter-gatherers would cope in Arctic regions if they did not continue to consume their high protein, high fat, animal-resourced foods, even for women throughout pregnancy.
Across the world, during the Upper Palaeolithic, the range of different dietary behaviours expanded according to location. In cold temperature and sub-Arctic Eurasia, populations were dependent almost entirely upon animals for food. In the tropics, populations would have existed on a much more general hunting and gathering strategy. In coastal regions and around freshwater lakes and rivers, fishing was incorporated, so that in some localities it represented the greatest component of protein in the diet.