The origins of agriculture, which includes both crop and livestock production, are traced back 10 000 years to the start of the Holocene. Before that, the genus Homo had lived for more than 2 million years by gathering plants and hunting wild animals for food, and Homo sapiens continued this practice for 100 000 years. For the last 5000 years, virtually the entire world’s population has been reliant on farmers and herders who consciously manipulate natural plants and animals to provide food. As global population has grown, the area used for food production has expanded and production techniques have become increasingly sophisticated. Both the extensification and the intensification of food production have thrown up numerous environmental issues. Many of these are covered in this chapter, but other environmental impacts of agriculture are dealt with elsewhere. These include the problems associated with the clearance of forests for farming (Chapter 4), the environmental impacts of heavy grazing in drylands (Chapter 5), soil erosion on agricultural land (Chapter 14) and some of the impacts associated with irrigation (Chapters 5, 8 and 9). Most of the world’s food supply is produced on land, but fish farming has grown in importance in recent years and is detailed in this chapter. Nevertheless, the majority of fish are still hunted, and environmental issues surrounding this form of food production are covered in Chapter 6.