Animals can be kept extensively or intensively. It avoids intensively cultivated areas and settlements. Many countries have introduced laws to regulate treatment of intensively farmed pigs. These and other measures have cut biodiversity to very low levels on intensively farmed land. Saccharum officinarum is one of the most productive and most intensively cultivated kinds of sugarcane. The mechanisms by which influenza infection causes symptoms in humans have been studied intensively. Model organism databases provide in-depth biological data for intensively studied. Critics of intensively farmed crops cite a wide range of concerns. Urban farms typically use techniques that allow them to produce intensively on small land. It is one of the most intensively studied species in the genus. Aspartame is one of the most intensively scrutinized food additives. It is, therefore, one of the most intensively farmed areas of the game. Mass loss is one of the most intensively studied aspects of massive star research. Such areas are distinct from more intensively settled urban and suburban areas. Language learning normally occurs most intensively during human childhood.