Population ageing has been evidentially proven to be caused by two dominant factors, declining fertility rates and rising life expectancy or improving mortality rates. Ideally, any population is derived by subtracting the number of deaths from the number of births, giving a specific number of the population of a particular city or country. To add to its complexity, the number of departures is subtracted from the number of arrivals, giving a perfect number of the migrant population that adds to the resident citizen population. These figures give an ideal population number to be assessed for searching the cause of its ageing.
It has been noticed that fertility rate has been a major contributor to the phenomenon of population ageing, more than the rise in mortality rates. This is because the younger population being more in number and in their active reproductive years could easily triumph the rise in the number of mortality rates. Moreover, the decline in fertility rates affects the childbearing abilities of women. The fertility rate, indicating the child birth per women, of the world has come down from 5 in 1960 to 2.4 in 2015 (Data.worldbank.org, 2017). This infers that a single woman in 1960 was giving birth to 5 children, and a single woman is giving birth to only 2.4 children in 2015. This decline is one of the major causes of the rise of population ageing, because when fertility declines, the childbearing decreases, causing a decline of young population and the existence of aged population that age. Moreover, the young population who remain infertile and cannot bear children lead their lives without any progeny and thus add up to the number of aged population.
There have been major reasons that are controversial for the rise in declining fertility, because from 1960 to 2015, the world has developed and equipped itself with more technological tools and equipment that cure infertility and suppress the rising number of infertile couples. The reasons are more than just lack of healthcare access but precisely about the impact of the globalization on the human species in different nations. The rise of technology, inventions of internet and mobile communication, rise in sedentary lifestyles, decline in physical activities and any motivation for exercising, and lifestyle diseases catching up in developed and also developing world have contributed to the fertility rates worldwide. The means and comforts meant for eradicating medical and health issues are the ones that have been said to be affecting the most, of which the most popular is the rise in unhealthy food habits.