Thursday, July 24, 2008

Pre-Agricultural Diet

A lot of people have the idea that early man led a miserable existence without the benefit of modern nutrition. That he generally died very young at around thirty or so. I wonder if this was so. I wonder if somehow people have mixed up agricultural societies with hunter gatherers or have based their conclusions on people living in extreme situations.

When Europeans first arrived in the New World they encountered many people at various levels of “civilization”. From the reading I have done the Indians that lived in what is now known as the United States and Canada seemed to be fine physical specimens before suffering from introduced diseases and influences. Further south I always get the impression that the more civilized types like the Inca and Aztec were a bit feeble – they were after all over run by a mere handful of Spaniards and they numbered in the millions. Plains Indians on the other hand gave the US cavalry a real run for their money almost reversing the situation in some aspects. I wonder if the civilized diet led to weakness of a moral as well as physical character. I have also read that the bones of people living in early civilizations show more signs of arthritis than their wilder counterparts and that this was a result of eating too many grains. The eating of high carb foods like wheat, rice and corn for breakfast, lunch and dinner has always led to health problems associated with vitamin deficiency and weakness. Wild man, on the other hand, ate a diet rich in animal products and augmented it with vegetables and fruits that were intensely nutritious compared to the engineered stuff we eat today. Even tribes that ate a diet almost entirely of meat were astoundingly healthy without any heart disease or cancer. Yet there are many cases of disease resulting from diets that relied heavily on rice, potatoes or corn.

Humans have spent the vast majority of their history in a state of pre-agriculture. It is logical to conclude that the human body has adapted to a pre-agricultural diet as five to ten thousand years is not enough time for evolution to have a significant effect.

Thinking about what pre-agricultural man ate could give us some clues as to the reason behind the obesity epidemic we are facing today. He probably had access to animal protein and fat all year round. Food high in carbohydrate was reasonably rare and highly seasonal. Fruits, tubers, honey and grains would be available in much smaller quantities and with far less sugar than we see today. Carbohydrates supply the body with energy but the body doesn’t need or cannot use the energy gained from gorging on high carb foods immediately so it stores the excess as fat. This may aid human survival as fat will be deposited in the summer for the lean times encountered in the winter. The human body encountered periods of feast and famine regularly and adapted to cope with this reality by readily storing excess carbohydrate as fat. Meat eaters don’t seem to do this for reason s that are not entirely clear. It may be because meat is available regardless of season or that prey’s nutritional value actually gets better as winter approaches due to fat deposits. It may also be because fat and protein need to be first converted into glucose before it can be deposited as fat and this takes a fair bit of energy.

So today we have a situation of continuous feast and this is not good for weight control or health because we are not adapted to it. We either need to induce periods of famine to reduce our stored fat deposits by dieting or eat a diet high in protein and animal fat to maintain a steady body weight. It seems pretty obvious to me.
PS. Not much body fat on that Indian depicted above - looks a bit like me actually. I bet he didn't eat a lot of carbs!

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