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.
They discovered humans carry extra copies of a gene, called AMY1, which is essential for making the salivary enzyme amylase that digests starch.
And marginal food resources can become part of the staple diet.
"Now you can have population growth and expand into new territories."
clipped from: news.bbc.co.uk