section_path: Background
section_name: Background
paragraph_text: Background
  
  Hunter-gatherers had different subsistence requirements and lifestyles from agriculturalists. Hunter-gatherers were often highly mobile and migratory, living in temporary shelters and in small tribal groups, and having limited contact with outsiders. Their diet was well-balanced though heavily dependent on what the environment could provide each season. In contrast, because the surplus and plannable supply of food provided by agriculture made it possible to support larger population groups, agriculturalists lived in more permanent dwellings in more densely populated settlements than what could be supported by a hunter-gatherer lifestyle. The agricultural communities' seasonal need to plan and coordinate resource and manpower encouraged division of labour, which gradually led to specialization of labourers and complex societies. The subsequent development of trading networks to exchange surplus commodities and services brought agriculturalists into contact with outside groups, which promoted cultural exchanges that led to the rise of civilizations and technological evolutions.
  
  However, higher population and food abundance did not necessarily correlate with improved health. Reliance on a very limited variety of staple crops can adversely affect health even while making it possible to feed more people. Maize is deficient in certain essential amino acids (lysine and tryptophan) and is a poor source of iron. The phytic acid it contains may inhibit nutrient absorption. Other factors that likely affected the health of early agriculturalists and their domesticated livestock would have been increased numbers of parasites and disease-bearing pests associated with human waste and contaminated food and water supplies. Fertilizers and irrigation may have increased crop yields but also would have promoted proliferation of insects and bacteria in the local environment while grain storage attracted additional insects and rodents.