Vocabulary Agricultural Density - The ratio of the number of farmers to the total amount of land suitable for agriculture. Agricultural Revolution - The time when human beings first domesticated plants and animals and no longer relied entirely on hunting and gathering. Arithmetic Density - The total number of people divided by the total land area. Census - A complete enumeration of a population. Crude Birth Rate (CBR) - The total number of live births in a year for every 1,000 people alive in the society. Crude Death Rate (CDR) - The total number of deaths in a year for every 1,000 people alive in a society.