Gender

Figure 1 presents sex ratios for three age groups throughout the world. The sex ratio is the number of males per 100 females. At birth, the sex ratio is generally around 105. In other words, there are more male babies born than female babies. This pattern is found in almost all societies. In the middle ages of the life course, there tends to be almost equal numbers of men and women, but by age sixty-five, the sex ratio is skewed heavily in favor of females. Generally, based on the world average, there are one-third more females than males age sixty-five and older. However, there are regional differences. In Asia, Latin America, and Africa there are about one-fifth more older females than older males, while in Europe there are almost two-fifths more older women. There is more detailed information for the United States, in which the sex ratio falls below 50 for ages eighty-five to eighty-nine, indicating that there are more than twice as many females as males in this age range. For those over one hundred years old, the sex ratio is a mere twenty-one—that is, there are twenty-one males per one hundred females. This pattern of highly skewed sex ratios is the result of gender differences in life expectancy, which are discussed in the next section.