Human Evolution, Diet and Health:
The Case for Palaeolithic Nutrition
Over recent years there has been growing interest in human evolution, and the potential for diets based on what we think our prehistoric, palaeolithic ancestors ate to improve our health. This book is an exploration of this idea. The book contains a wealth of background information regarding our current understanding of human evolution, and what drove the most important steps on the path to modern humans. There is an introduction to key concepts in evolution, including evolutionary success, brain size, tool use, food procurement and gut length.
Shortcomings in the typical, westernised diets are discussed, as are associations between obesity, modern diseases and aspects of many modern diets around the world. Our physical anatomy and our physiology evolved over millions of years, and were met with a swift and considerable change in food availability over the last few thousand years. Progressions in technology have led to processing techniques that may harm a food's nutritional composition. Indeed, it is the adoption of novel foods, and the high consumption of foods that were historically consumed to a much smaller degree, that has exposed us to some deficiencies and disease.
The reader is expected to draw their own conclusions regarding the sorts of foods they want to increase or limit in their daily diets. This is not a book to dictate hard and fast diet rules, but simply to offer-up some of the science of evolution, human nutrition, health and disease. From this, the reader can make informed decisions about how best to support and promote their own health.
Excerpt: Diet and the Human Genome
Our entire physiology has been naturally selected for over the course of millions of years, yet in the last hundred years we have become increasingly sedentary, and almost everything that we eat is farmed, even the fruits that we might expect to be entirely 'natural' and unchanged. The result is a vast difference between our current lifestyles and that in which our genotype evolved. The imbalance between our current existence, and that of our ancestors manifests itself in disease, obesity and ill health.
Our genes are those that were selected for when our ancestors were Palaeolithic hunter-gatherers. Since then, and despite vast changes in our lifestyles, our genetics have changed very little. Our current nutritional requirements are the result of the interaction of our ancestors with their environment, going back through time to the very beginning of life on Earth.
Put another way, there has not been sufficient time for natural selection to evolve an effective defence for our genes to prevent the onslaught caused by our westernised diets and westernised lifestyles. Because most human diseases are so often related to lifestyle, they should be preventable. It is the contribution of our modern stresses, our sedentary lifestyles, our consumption of farmed, manipulated and processed foods, and of chemicals, both within the foods and as pharmaceuticals, which have led to our decreasing resistance to disease. To really understand what we need to be healthy, we should examine our lifestyle, including our diet, as it was when the modern human genotype was interacting naturally with its environment. This, so far as can be reasonably hypothesised, was the period when humankind should be expected to be at its healthiest; physically and mentally fit, and almost (if not entirely), free from obesity and disease.
Researchers of human nutrition are increasingly investigating the role that our evolution has played, both in the development of our physiology and in the lifestyle-related diseases of westernised societies. In the United States, for example, chronic illness and health problems either entirely or partially attributable to diet are the single greatest threat to public health. 65% of adults in the U.S. aged twenty years or over are either overweight or obese, and the estimated number of deaths due to obesity is over 280,000 per year.
More than 64 million Americans have at least one type of cardiovascular disease, which represents the leading cause of mortality (38.5% of all deaths) in the United States. 50 million Americans have high blood pressure, 37 million have high-risk total cholesterol concentrations, and 11 million have type II diabetes. Furthermore, in post-menopausal women aged 50 or over, 39.6% have osteopenia and 7.2% have osteoporosis.
Osteoporosis increases the risk of fractures, and osteoporotic hip fractures are associated with a 20% excess mortality in the year following the fracture. The second leading cause of death in the United States (representing approximately 25% of all deaths) is cancer. An estimated one-third of all cancer deaths are due to nutritional factors, including obesity. That many of these conditions are not observed in modern populations still living a hunter-gatherer way of life, confirms the worthiness of investigations into our pre-agricultural ancestry.