Population aging refers to the increasing proportion of older people (typically defined as those aged 65 or older) in a population.

The dependency ratio is the ratio of the number of people of retirement age (typically defined as those aged 65 or older) to the number of people of working age (typically defined as those aged 15 to 64).

Population aging is caused by a combination of factors, including increased life expectancy, decreased fertility rates, and migration of younger people to other countries.

Population aging can lead to a number of challenges, including increased healthcare costs, increased pension costs, and a shortage of workers.

Population aging can also have some potential benefits, such as increased wisdom and experience in the workforce, increased volunteerism and community engagement, and increased innovation and creativity.

Japan has the highest dependency ratio in the world, with a ratio of 64.6% in 2020.

Niger has the lowest dependency ratio in the world, with a ratio of 8.7% in 2020.

The projected global dependency ratio in 2050 is 34.6%.

The relationship between population aging and economic growth is complex and depends on a number of factors, including the age structure of the population, the level of education and skills of the workforce, and the government's policies.

Governments can consider a number of policy options to address the challenges of population aging, including raising the retirement age, increasing immigration, and investing in education and training.

The impact of population aging on the environment is complex and depends on a number of factors, including the age structure of the population, the consumption patterns of older people, and the government's policies.

The impact of population aging on social cohesion is complex and depends on a number of factors, including the age structure of the population, the level of inequality in society, and the government's policies.

The impact of population aging on political stability is complex and depends on a number of factors, including the age structure of the population, the level of inequality in society, and the government's policies.

The impact of population aging on cultural change is complex and depends on a number of factors, including the age structure of the population, the level of education and skills of the workforce, and the government's policies.