Grumpy potato photo by banger1977/flickr
"...The importance of potatoes first hit home for co-author Nancy Qian during a trip to rural Rwanda, where she noticed something about her hosts' diet. "All they were eating were potatoes," she says..."
"...Qian, along with Harvard University's Nathan Nunn, decided to see how universal the connection was. Looking at population trends from 1700, when the potato was introduced to the Old World, to 1900, they estimated that 12 percent of the population growth and 47 percent of the urbanization during this period was directly potato-related. ..."