Understanding our Population
introduction of machinery powered by fossil fuels, marked by the shift from a rural, agriculture-based society to an urban, industry-based society
Industrial Revolution
the change in size of a population over a specific period
Growth rate
the thin layer of gases that surrounds Earth
Atmosphere
the study of human populations
Demography
the birthrate at which a nation’s population size stays the same
Replacement fertility
the circulation of nutrients through the atmosphere; also called nutrient cycle
Biogeochemical cycle
the difference in assets and income between individuals in a society or between nations
Wealth gap
the average number of years an individual can expect to live
Life expectancy
Cellular respiration
the process by which organisms use oxygen to release the chemical energy of sugars, producing carbon dioxide and water
number of people living per unit of space (e.g., per square kilometer)
Population density
the average number of children a female member of a population gives birth to during her lifetime
Total fertility rate
the variable that is manipulated, or changed, in an experiment
Independent variable
a theory that links lower birthrates and death rates in a population to improvements in education, economic conditions, and health care
Demographic transition
the number of infants per 1000 live births in a population that do not survive the first year of life
Infant morality
a well-tested explanation of observations and experimental findings
Theory