Short answers, pulled from the story.
Agriculture began when nascent farmers started planting grains around 11,500 years ago. Humans had gathered wild grains for at least 105,000 years before they began planting them. Sheep, goats, pigs, and cattle were domesticated around 10,000 years ago.
Plants were independently cultivated in at least 11 separate centers of origin around the world. These ranged from rice in China and the potato in the Andes to maize bred from wild teosinte in Mesoamerica and sorghum in the Sahel region of Africa.
Small farms, the vast majority of which are one hectare or smaller, produce about one-third of the world's food. Five of every six farms in the world consist of fewer than 2 hectares but take up only around 12 percent of all agricultural land.
Livestock production is responsible for 18 percent of the world's greenhouse gas emissions measured in CO2 equivalents. It also produces 65 percent of human-related nitrous oxide and 37 percent of all human-induced methane, and occupies 70 percent of all land used for agriculture.
The International Labor Organization considers agriculture one of the most hazardous of all economic sectors. It estimates the annual work-related death toll among agricultural employees at at least 170,000, twice the average rate of other jobs, with tractor rollovers a common cause of fatal injuries in developed countries.
Agriculture needs to produce about 50 percent more food, feed, and fibre by 2050 compared with the volumes generated in 2012, according to the Food and Agriculture Organization of the United Nations. Current global production amounts to approximately 11 billion tonnes of food, though around 14 percent is lost before reaching retail.