The Evolution of Us – Genetic Links to How Our Bodies Digest Carbohydrates


Amylase is a case where diet may have the potential to change our genes. Populations that have higher numbers of amylase gene copies and more amylase in their saliva tend to eat more starch and were found to digest starchy carbohydrates faster. They also displayed a higher blood glucose response to foods containing starch such as bread and pasta. There has been speculation it could represent an adaptation to the influence of diet during human evolution, perhaps associated with the shift from the low starch diet of hunter-gatherers to the high starch diets of Neolithic farmers.

It has been found that even animals that live alongside humans have diets that are different to those of their wild relatives, and these differences have led to dietary adaptations. While wolves are highly carnivorous, dogs have adapted to eating starchy human food scraps.
Amylase, which kick-starts digestion of starch in the mouth, is associated with blood glucose levels and digestion of carbohydrates, with implications for understanding human evolutionary biology and the gut microbiome.

A study investigated the relationship between body weight and amylase, which is responsible for an enzyme present in our saliva. This enzyme is the first to be encountered by food when it enters the mouth, beginning the process of starch digestion which continues in the gut.

The study explains that people usually have two copies of each gene, but there is variability in the number of copies a person carries and it is believed that higher numbers of copies of the salivary amylase gene have evolved in response to a shift towards diets containing more starch.

Researchers from Imperial College London looked at the number of copies of the gene AMY1 present in the DNA of thousands of people from the UK, France, Sweden and Singapore. They found that people who carried a low number of copies of the salivary amylase gene were at greater risk of obesity and estimated that with every additional copy of the salivary amylase gene there was approximately a 20 per cent decrease in the odds of becoming obese. The study suggested that how we digest starch and how the end products from the digestion of complex carbohydrates behave in the gut could be important factors in the risk of metabolic disfunction.

The following incredibly informative and visually stunning documentary looks at this topic and other areas in which evolution from hunter gatherers to the advent of agriculture has shaped the human race for better…or worse.

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