population aging is the increase in the number and proportion of older people in society. population aging has three possible causes: migration, longer life expectancy (decreased death rate) and decreased birth rate. aging has a significant impact on society. young people tend to have fewer legal privileges (if they are below the age of majority), they are more likely to push for political and social change, to develop and adopt new technologies, and to need education. older people have different requirements from society and government, and frequently have differing values as well, such as for property and pension rights.