EVERYDAY SCIENCE

Detailed explanation-1: -High rates of infant and childhood deaths and short lifespans put a limit on population growth in the past. However, improvements in nutrition, water, medical care and other technological advances have contributed to a sharp decline in deaths while births continue to increase, resulting in population growth.

Detailed explanation-2: -Natural increase usually accounts for the greatest amount of growth in a population, especially within a short period of time. For the world, growth occurs only when there are more births than deaths; for individual countries, migration is also a factor.

Detailed explanation-3: -The major findings were that social factors-such as education, child marriage, contraception use, and religion-correlate most strongly to population growth. Educated couples tend to have fewer children. People who are more religious tend to have more children.

Detailed explanation-4: -There are two things that increase a population size. Populations can increase as a result of birth rate and immigration. Natality is the ratio of the number of births to the size of the population.

Detailed explanation-5: -There are three components of change: births, deaths, and migration. The change in the population from births and deaths is often combined and referred to as natural increase or natural change.