1. Physiological Density A more meaningful population measure is looking at the number of people per area of a region. Arable land- land suited for agriculture Example: In the U.S. the physiological density is 172 persons per kilometer (445 per square mile) of arable land – Egypt has 2,580 persons per square kilometer (6,682 per square mile) of arable land = This large difference in physiological densities demonstrates crops grown on a hectacre of land in Eygpt must feed far more people than in the U.S.

2. Example: In the U.S. the physiological density is 172 persons per kilometer (445 per square mile) of arable land – Egypt has 2,580 persons per square kilometer (6,682 per square mile) of arable land = This large difference in physiological densities demonstrates crops grown on a hectare of land in Egypt must feed far more people than in the U.S.

3. The higher the physiological density- the greater the pressure people may put on the land to produce food Provides insights into the relationship between the size of a population and availability in a region