Scientists have discovered that a key gene for digesting carbohydrates dates back even before the emergence of the first humans, according to a recent study published in Science.
Scientists participating in the study have traced the evolution of the human salivary amylase gene, AMY1, which is responsible in part for starch digestion. They discovered that the gene has been around for a very long time—up to 800,000 years, in fact, long before our species, Homo sapiens, or even Neanderthals.
The discovery was made by examining the DNA of 98 living people and comparing it with the DNA of ancient humans and archaic hominins, the scientists said, adding that by comparing 30 different ways the AMY1 arranged itself in modern humans, scientists were able to identify a version of the gene in these ancient beings.
Modern humans have many copies of AMY1, with the number varying from person to person. The ancient beings, however, were found to have three copies. This did not necessarily limit the amount of carbs that could be consumed; rather, it showed the early stages of AMY1’s evolution.
What was the goal of the study?
“The main question that we were trying to answer was, when did this duplication occur? So that’s why we started studying ancient genomes,” the study’s first author, Feyza Yilmaz, an associate computational scientist at The Jackson Laboratory, was cited by CNN as saying.
“Previous studies show that there’s a correlation between AMY1 copy numbers and the amount of amylase enzyme that’s released in our saliva. We wanted to understand whether it’s an occurrence that is corresponding to the advent of agriculture. This is … a hot question,” she noted.
Additionally, CNN reported that the new research supports the theory that carbohydrates, rather than proteins, provided the energy bump necessary for the increase in human brain size over time, as noted by Taylor Hermes, an assistant professor in the Department of Anthropology at the University of Arkansas, who wasn’t involved in the research.
“The authors finding that an increased copy number of the amylase gene, which results in a greater ability to break down starch, may have emerged hundreds of thousands of years before Neanderthals or Denisovans gives more credit to the idea that starches were being metabolized into simple sugars to fuel rapidly growing brain development during human evolution,” Hermes said.