Changing fertility, mortality, and migration rates make up the total population composition, a snapshot of the demographic profile of a population. This number can be measured for societies, nations, world regions, or other groups. The population composition includes the sex ratio, the number of men for every hundred women, as well as the population pyramid, a picture of population distribution by sex and age (Figure 20.5). Figure 20.5 This population pyramid shows the breakdown of the 2019 U.S. population according to age and sex. (Credit: Populationpyramid.net) Country Population (in millions) Fertility Rate (number of children per adult women) Mortality Rate (per 1,000 births) Sex Ratio Male to Female Afghanistan 38.4 4.4 48 1.05 Finland 5.52 1.4 2.0 1.04 United States of America 328.3 1.7 5.7 0.97 Table 20.1 Varying Fertility and Mortality Rated by Country - As the table illustrates, countries vary greatly in fertility rates and mortality rates—the components that make up a population composition. This data is from 2018, and changes occur continually. For example, in 2014, the number of children per adult woman in Afghanistan was 5.4 – generally an average of one more child per family. And the U.S. was slightly higher at 2.0 (World Bank 2019) Comparing the three countries in Table 20.1 reveals that there are more men than women in Afghanistan and Finland, whereas the reverse is true in the United States. Afghanistan also has significantly higher fertility and mortality rates than either of the other two countries. In all three cases, the fertility rates have dropped in recent years, but Afghanistan's drop (from 5.4 children per woman to 4.4) will likely be the most impactful (World Bank 2019). Do these statistics surprise you? How do you think the population makeup affects the political climate and economics of the different countries?

You've reached your AI usage limit