The describe aging as a gradual withdrawal from the world in which people separate themselves from others on physical psychological, and social levels,

The "disengagement theory" describe aging as a gradual withdrawal from the world.

The disengagement theory proposes that at a certain stage in life it is not avoidable to disengage or withdraw from the world on social and physiological levels. There are various versions of the theory for example moral disengagement etc.

answer; grew into towns and cities;

answer; goals and feedback are present;