Final answer:
In countries like Zambia and Angola, nearly half of the population is not expected to survive to age 40 due to high infant mortality rates, undernourishment, and lack of access to essential services like safe drinking water.
Step-by-step explanation:
In low income countries such as Zambia and Angola, nearly half of the total population in each nation is not expected to survive to age 40. Infant and young child mortality rates are disproportionately high in these countries, where babies born are 16 times more likely to die before the age of five compared to high-income nations. Contributing factors to lower life expectancy in these regions include high rates of undernourishment, illiteracy, lack of access to safe drinking water, and inadequate medical care.
The high mortality rates affect the demographic composition and the dependency ratio of these countries, putting strain on economic development and living standards. While nations like Angola face a myriad of issues ranging from famine to disease and environmental pollution, demographic changes over time are also expected to impact the varying age groups within the populations, altering the standard of living. Nonetheless, by 2050, the elderly populations in low-income countries are expected to increase significantly, which may change the current demographic trends and their associated challenges.