Our taste for bread and pasta wouldn’t be the same if it weren’t for our ability to break down starch – a talent that, thousands of years ago, the Andean populations of Peru took to the extreme.
A new study – led by researchers at the University of California, Los Angeles (UCLA), and this Tuesday at Nature Communications – revealed that the indigenous andean have, on average, up to four times the number of genes for a digestive enzyme that breaks down starch in your saliva than any other population.
Closer analysis of the gene sequences suggests that this extraordinary count is the result of a selection event around 10,000 years ago – precisely. at a time when potatoes were coming into culinary vogue.
To , the leader of the investigation, Omer Gokcumensays he does not believe that this temporal coincidence is mere chance.
Starch is a complex sugar used by plants for energy storage. Like many animals, humans rely on a suite of enzymes to break down this material into a form that can be quickly metabolized.
One of these enzymes, called salivary amylaseis encoded by the gene AMY1.
Most of us have at least two copies of this genethanks to its duplication around 800,000 years ago, increasing our ability to start breaking down starch the moment we put a piece of food in our mouth.
Some populations have many more than two copies of AMY1although it is difficult to determine whether these multiples are a direct consequence of dietary changes.
To find solid evidence, UCLA researchers performed a genomic analysis on more than 3,700 individuals from 83 populations and compared the typical number of AMY1 genes in each.
It was found that the indigenous Andeans have, on average, 10 copies of the genecompared to an average of seven copies in other populations around the world.
The new study identified a clear selection signature to favor individuals who, by chance, had numerous copies of AMY1at a time when potatoes were being added to the Andean menu.
Having more copies of the salivary amylase gene provides a slightly higher concentration of starch-digesting enzymes, which, according to the researchers’ calculations, gave ancient Peruvians a 1.24% greater probability of surviving long enough to have more children.
This may not seem like much, but over thousands of years made indigenous Andeans world leaders in starch digestion.
