The Irish Potato Famine lasted just a few years, from around 1845 to 1852, but killed about a million people and forced the emigration of around a million more. The Irish population at that point was reliant on one specific white potato, the Irish lumper, as a primary food source for about a third of the country. Potatoes, like most other members of the nightshade family (tomatoes, eggplant), are native to the New World, not to Ireland. In the mid-19th century, travel between the New and Old World increased, bringing over new strains of Phytophthora infestans. One of those strains eventually mutated into a killer.