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Starch, Milk and Alcohol
Wed 3 May 2017, 12:30 – 13:30 BST
Dr Giles Yeo, MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Labs explores the genetic and cultural history of our dietary relationship with starch, milk and alcohol and dispels some of the myths surrounding fad diets
For most of the 200,000 years of our existence, all humans were hunter-gatherers. Then between 11,000 – 4,500 years ago, food production based on the domestication of a few animal and plant species arose and spread throughout the world. This agricultural revolution meant far higher food yields and the ability to support higher population densities. This increased productivity also allowed for the accumulation of stored food, allowing for the emergence of non-food-producing specialists in society, leading to the subsequent development of complex technology and social stratification, thus here we are today. Hurrah.
The shift from hunter-gatherer to farmer however, occurred in 5% of our time on earth, an evolutionary blink of an eye. The problem with this rapid change is that the varied and unpredictable diet of the hunter-gatherer, which we have spent 95% of our existence genetically evolving and adapting to, is very different to the far less varied farming diet. Today, five grasses (wheat, rice, oats, corn and barley), four large mammals (the cow, pig, sheep and goat) and one bird (the chicken) provide the vast majority of our calories and sustain human existence. The transition from hunter-gathering to farming was initially associated with a heavy disease-burden, because early farmers had not yet adapted to their new diet, causing deleterious digestive disorders. Three key adaptations eventually allowed us to take advantage of these new food supplies, associated with the emergence of farming.
The first is our ability to digest starch in large amounts; the second is our ability as adults, to consume milk and their related products; and third is our ability to drink and metabolize alcohol. Of course, you will recognize that the latter two abilities vary dramatically across different ethnicities; yet, all three, to varying degrees have been critical for our survival, providing us with a huge selection advantage over hunter-gatherers. These adaptations are now variously and deeply embedded in human cultural identity; and all required discrete genetic adaptations.