Man's ability to digest starchy foods like the potato may explain our success on the planet, genetic work suggests.
Compared with primates, humans have many more copies of a gene essential for breaking down calorie-rich starches, Nature Genetics reports. And these extra calories may have been crucial for feeding the larger brains of humans, speculate the University of California Santa Cruz authors. Previously, experts had wondered if meat in the diet was the answer.
However, Dr Nathaniel Dominy and colleagues argue this is improbable.
"Even when you look at modern human hunter-gatherers, meat is a relatively small fraction of their diet. "To think that, two to four million years ago, a small-brained, awkwardly bipedal animal could efficiently acquire meat, even by scavenging, just doesn't make a whole lot of sense."
They discovered humans carry extra copies of a gene, called AMY1, which is essential for making the salivary enzyme amylase that digests starch.
Next the team studied groups of humans with differing diets and found those with high-starch diets tended to have more copies of AMY1 than individuals from populations with low-starch diets.
For example, the Yakut of the Arctic, whose traditional diet centres around fish, had fewer copies than the related Japanese, whose diet includes starchy foods like rice.
Source - BBC