Explanation:
increase in longevity raises the average age of the population by increasing the numbers of surviving older people. ... More specifically, it is the large decline in the overall fertility rate over the last half century that is primarily responsible for the population ageing in the world's most developed countries.
Developing countries fall relatively behind developed countries in terms of infrastructure, access of the population to sanitation, healthcare, safe drinking, water, and energy, security, and pollution-free environment and tend to show a higher degree of poverty, corruption, and political instability.
