9.2: Life Expectancy

Longevity and Life Expectancy

Lifespan or Maximum Lifespan is referred to as the greatest age reached by any member of a given population (or species). For humans, the lifespan is currently between 120 and 125. Life expectancy is defined as the average number of years that members of a population (or species) live. Pre-COVID-19, the World Health Organization (WHO) (2019) reported that the global life expectancy for those born in 2019 was 72.0 years, with females reaching 74.2 years and males reaching 69.8 years. Women lived longer than men around the world, and this gap has remained the same since 1990. Life expectancy ranged from 61.2 years in the WHO African Region to 77.5 years in the WHO European Region. Overall, global life expectancy increased by 5.5 years between 2000 and 2016. Improvements in child survival and access to antiretroviral medication for the treatment of HIV were considered factors for the increase. However, life expectancy in low-income countries (62.7 years) was 18.1 years lower than in high-income countries (80.8 years). In high-income countries, the majority of people who died were old, while in low-income countries almost one in three deaths were in children under 5 years of age.

COVID-19 and World Life Expectancy

According to a recent WHO report (2022) current estimates indicate that the COVID-19 pandemic is either slowing or reversing the rising trend for life expectancy in the world. The WHO report found that life expectancy in 2020 had fallen in all but three of 37 high income and upper middle income countries compared with 2019, with men experiencing a greater decline in life expectancy. The study estimated that more than 28 million excess years of life were lost in 2020 in those 37 countries.

Woolf et al. (2022) looked specifically at comparing 2020 life expectancy in the U.S. with 21 peer countries. While the 2020 U.S. life expectancy decreased 1.8 years from 2019 to 77 years, the average decrease in life expectancy among the comparison countries was only 0.58 years. No peer country experienced decreases as large as those seen in the U.S. The average life expectancy in the peer countries was 81.50 years, which was 4.5 years higher than the U.S. life expectancy. Outcomes in peer countries ranged from a decrease of 1.43 years in Spain to increases in life expectancies in New Zealand, South Korea, and Taiwan. In Denmark, Finland, and Norway, life expectancy did not change significantly. Given that COVID-19 mortality and excess deaths in the U.S. were among the highest in the world, it is not surprising that the decline in U.S. life expectancy exceeded the declines in other countries, Since 2010, U.S. life expectancy has remained stagnant, and even decreased for three consecutive years from 2014 to 2017. In contrast, life expectancy in other countries continued to increase resulting in a widening life expectancy gap with peer nations. This 2020 preliminary evidence proposes that the gap with other countries increased even further during the COVID-19 pandemic.

World Healthy Life Expectancy

A better way to appreciate the diversity of people in late adulthood is to go beyond chronological age and examine how well the person is aging. Many in late adulthood enjoy better health and social well-being than average and would be aging at an optimal level. In contrast, others experience poor health and dependence to a greater extent than would be considered normal. When looking at large populations, the WHO (2024) measured how many equivalent years of full health on average a newborn baby is expected to have. This age considers current age-specific mortality, morbidity, and disability risks and is referred to as the Healthy Life Expectancy. Figure \(\PageIndex{1}\) shows the differences in life expectancy between the top 5 and the lowest 5 nations. Green bars on the left show the five highest life expectancies: Monaco 86.7, San Marino 86.0, Hong Kong 85.9, Japan 85.2, and South Korea 84.6 years. Red bars on the right show the five lowest: Lesotho 58.6, Central African Republic 58.1, South Sudan 58.0, Chad 55.6, and Nigeria 55.0 years.

Figure \(\PageIndex{1}\): Life expectancy at birth for the five highest and five lowest ranked countries worldwide, 2024. The gap between the top-ranked country, Monaco, and the bottom-ranked country, Nigeria, was 31.7 years. (CC BY 4.0; via "Life expectancy at birth" by Our World in Data)

Based on WHO's World Health Statistics 2024 report, Global Healthy Life Expectancy rose from 58.1 years in 2000 to 63.5 years in 2019, before the COVID-19 pandemic reversed nearly a decade of that progress. Between 2019 and 2021, global HALE fell by 1.5 years, back to 61.9 years, its lowest level since 2012. The impact was uneven across WHO regions: the Americas and South-East Asia were hit hardest, each losing roughly 2.5 years of healthy life expectancy over that period, while the Western Pacific Region was least affected, with losses of less than 0.1 years, leaving it with the highest life expectancy of any WHO region.

COVID-19 and Life Expectancy in America

COVID-19 has had a significant impact on life expectancy in the U.S. From 2000 to 2019, life expectancy in the United States rose slowly but steadily for both sexes, gaining about two and a half years overall: the total population's life expectancy climbed from 76.8 to 78.8 years, men's from 74.1 to 76.3, and women's from 79.3 to 81.4. Figure \(\PageIndex{2}\) shows this trend, along with the sharp reversal that followed, tracked across three lines for Female, Total, and Male life expectancy from 2000 to 2024.

The overall life expectancy for a baby born in 2020 was 77.0 years, down from 78.8 years in 2019 (Murphy et al., 2021). The decline from 2019 occurred for both males, falling from 76.3 to 74.2 years, and females, falling from 81.4 to 79.9 years. The gap in life expectancy between the sexes widened from 5.1 years in 2019 to 5.7 years in 2020.

Figure \(\PageIndex{2}\): Life expectancy at birth by sex in the United States, 2000-2024. The COVID-19 pandemic erased two decades of gains within two years, with male life expectancy falling to 73.5 in 2021, its lowest point since the mid-1990s, before recovering to a new high of 76.5 by 2024. (Public Domain; via National Center for Health Statistics (NCHS), National Vital Statistics System)

The decline continued into 2021, the pandemic's worst year for U.S. mortality. Total life expectancy fell further to 76.4, a drop of 2.4 years from 2019 in just two years, the steepest two-year decline in a century. Male life expectancy dropped to 73.5, its lowest point since the mid-1990s, while female life expectancy fell to 79.3. The sex gap widened again, to 5.8 years, the largest in decades.

Since 2021, life expectancy has climbed back steadily each year. By 2024, the total population reached a new record of 79.0 years, with men at 76.5 and women at 81.4. Men's recovery has been faster in percentage terms, narrowing some of the pandemic-era gap, though women still live noticeably longer on average.

Figure \(\PageIndex{3}\): Graph showing the life expectancy at birth and at age 65 by sex in the U.S. in 2019 and 2020. For all categories, life expectancy decreased between 1 and 2 years from 2019 to 2020. (Public Domain; via CDC).

Figure \(\PageIndex{3}\) based on NCHS data, compares life expectancy in the United States in 2019 versus 2020, both at birth and at age 65, broken down by sex. Life expectancy declined across every category shown, marking the first year of the COVID-19 pandemic's impact on U.S. mortality.

At birth, life expectancy for both sexes combined fell from 78.8 years in 2019 to 77.0 years in 2020, a drop of 1.8 years. The decline was steeper for men than women: male life expectancy fell 2.1 years, from 76.3 to 74.2, while female life expectancy fell 1.5 years, from 81.4 to 79.9. This uneven impact widened the long-standing gap between male and female life expectancy at birth.

The pattern held at age 65 as well, though the declines were smaller in absolute terms since fewer years of life remain at that age. Combined life expectancy at 65 fell from 19.6 years in 2019 to 18.5 years in 2020, a decrease of 1.1 years. Men at 65 saw life expectancy drop from 18.2 to 17.0 years, a loss of 1.2 years, while women at 65 saw a decline from 20.8 to 19.8 years, a loss of 1.0 year.

Taken together, the chart shows that the pandemic's toll was not confined to newborns' projected lifespans. Older adults who had already reached 65 also saw a measurable reduction in their expected remaining years of life, and in both age groups, men experienced a larger decline than women, a pattern that continued into 2021 before recovery began in the years that followed.

Ethnic Differences in Life Expectancy

Declines in U.S. life expectancy in 2020 varied greatly by race, ethnicity, and sex. Using final year-end mortality data, the National Center for Health Statistics found that every Hispanic-origin, race, and sex group experienced a decline, but the size of that decline differed sharply by group.

Figure \(\PageIndex{4}\) shows that Non-Hispanic American Indian or Alaska Native men saw the largest drop of any group, 4.8 years, falling from 68.6 to 63.8. Hispanic men were close behind, down 4.5 years, from 79.1 to 74.6, and non-Hispanic American Indian or Alaska Native women fell 4.3 years, from 75.0 to 70.7. Non-Hispanic Black men declined 3.5 years, from 71.3 to 67.8, and Hispanic women fell 3.1 years, from 84.4 to 81.3. Non-Hispanic Black women declined 2.7 years, from 78.1 to 75.4, and non-Hispanic Asian men fell 2.4 years, from 83.5 to 81.1. Non-Hispanic White men and non-Hispanic Asian women both declined 1.5 years, and non-Hispanic White women saw the smallest decline of any group, 1.2 years, from 81.3 to 80.1.

Looking at race and ethnicity alone (combining both sexes), the non-Hispanic American Indian or Alaska Native population lost the most, 4.7 years, followed by the Hispanic population at 4.0 years, the non-Hispanic Black population at 3.3 years, the non-Hispanic Asian population at 2.0 years, and the non-Hispanic White population at 1.4 years.

Figure \(\PageIndex{4}\): Change in life expectancy at birth by Hispanic origin, race, and sex, United States, 2019 to 2020 (final data). Non-Hispanic American Indian or Alaska Native men saw the steepest decline, 4.8 years, while non-Hispanic White women saw the smallest, 1.2 years. (Public Domain via; National Center for Health Statistics (NCHS), National Vital Statistics System, U.S. Department of Health and Human Services)

These final figures differ somewhat from earlier provisional estimates based on partial-year 2020 data, such as those used by Woolf et al. (2022), which projected a 3.70-year decline for the Hispanic population and a 3.22-year decline for the non-Hispanic Black population. The final data confirms the same overall pattern, pronounced, unequal declines concentrated most heavily among American Indian, Alaska Native, Hispanic, and Black populations, and men within every group experienced steeper declines than women in the same group.

Looking ahead, Andrasfay and Goldman (2022) found that racial and ethnic disparities persisted into 2021 as well, though they narrowed somewhat: reductions in life expectancy for Black and Latino populations that year were 1.3 to 1.9 times those for White populations, smaller than the 2020 gap but still evidence of continuing inequities.

Ethnic Disparity Causes

Data indicate that the percent of Hispanic/Latino, non-Hispanic Black, non-Hispanic American Indian, and Alaska Native people who died from COVID-19 in 2020 was higher than the percent of these racial and ethnic groups among the total U.S. population (CDC, 2021). Several factors have been identified for their higher COVID-19 death rates including that these groups were disproportionately represented among essential workers, including working in health care, security, retail, farming, factories, warehouses, food processing, food service, construction, grocery stores, and transportation (Mahr, 2021). In contrast, people who were in jobs that enabled them to work remotely were less likely to become infected. Racial and ethnic minorities were also disproportionately represented in settings with higher COVID-19 outbreaks, including correctional facilities, homeless shelters, long-term care facilities, and living in multi-generational homes (CDC, 2021). Additionally, disparities in medical care and underlying health conditions such as diabetes, hypertension, and heart disease disproportionately affect minorities. Entrenched racial discrimination has been identified as a contributing factor to all the disparities. The COVID-19 pandemic demonstrates the need to promote the health and well-being of racial and ethnic minorities (Mayo Clinic, 2021).

Gender Differences in Life Expectancy

Biological Explanations

Biological differences in sex chromosomes and different pattern of gene expression is theorized as one reason why females live longer (Chmielewski, Boryslawski, & Strzelec, 2016). Males are heterogametic (XY), whereas females are homogametic (XX) with respect to the sex chromosomes. Males can only express their X chromosome genes that come from the mother, while females have an advantage by selecting the "better" X chromosome from their mother or father, while inactivating the "worse" X chromosome. This process of selection for "better" genes is impossible in males and results in the greater genetic and developmental stability of females.

In terms of developmental biology, women are the "default" sex, which means that the creation of a male individual requires a sequence of events at a molecular level. According to Chmilewski et al. (2016):

These events are initiated by the activity of the SRY gene located on the Y chromosome. This activity and change in the direction of development results in a greater number of disturbances and developmental disorders, because the normal course of development requires many different factors and mechanisms, each of which must work properly and at a specific stage of the development. (p. 134)

Men are more likely to contract viral and bacterial infections, and their immunity at the cellular level decreases significantly faster with age. Although women are slightly more prone to autoimmune and inflammatory diseases, such as rheumatoid arthritis, the gradual deterioration of the immune system is slower in women (Caruso et al., 2013; Hirokawa et al., 2013).

Looking at the influence of hormones, estrogen levels in women appear to have a protective effect on their heart and circulatory systems (Viña et al., 2005). Estrogens also have antioxidant properties that protect against harmful effects of free radicals, which damage cell components, cause mutations, and are in part responsible for the aging process. Testosterone levels are higher in men than in women and are related to more frequent cardiovascular and immune disorders. The level of testosterone is also responsible, in part, for male behavioral patterns, including increased level of aggression and violence (Martin et al., 2011; Borysławski & Chmielewski, 2012). Another factor responsible for risky behavior is the frontal lobe of the brain. The frontal lobe, which controls judgment and consideration of an action's consequences, develops more slowly in boys and young men. This lack of judgment affects lifestyle choices, and consequently many more boys and men die by smoking, excessive drinking, accidents, drunk driving, and violence (Shmerling, 2016).

Lifestyle Factors

Certainly not all the reasons women live longer than men are biological. As previously mentioned, male behavioral patterns and lifestyle play a significant role in the shorter lifespans for males. One significant factor is that males work in more dangerous jobs, including police, fire fighters, and construction, and they are more exposed to violence. According to the Federal Bureau of Investigation (2014) there were 11,961 homicides in the U.S. in 2014 (last year for full data), and of those 77% were males. Males are also more than three times as likely to commit suicide (CDC, 2016a). Further, males serve in the military in much larger numbers than females. According to the Department of Defense (2015), in 2014 83% of all officers in the Services (Navy, Army, Marine Corps and Air Force) were male, while 85% of all enlisted service members were male.

Figure \(\PageIndex{5}\): Men have more dangerous jobs. (CC BY-NC-SA 4.0; via Lifespan Development: The Human Journey).

Additionally, men are less likely than women to have health insurance, develop a regular relationship with a doctor, or seek treatment for a medical condition (Scott, 2015). As mentioned in the middle adulthood chapter, women are more religious than men, which is associated with healthier behaviors (Greenfield et al., 2009). Lastly, social contact is also important as loneliness is considered a health hazard. Nearly 20% of men over 50 have contact with their friends less than once a month, compared to only 12% of women who see friends that infrequently (Scott, 2015). Overall, men's lower life expectancy appears to be due to both biological and lifestyle factors.

Figure \(\PageIndex{6}\): Men benefit from a relationship with a doctor. (CC BY-NC-SA 4.0; via Lifespan Development: The Human Journey).

American Healthy Life Expectancy

To determine the current United States Healthy Life Expectancy (HLE), factors were evaluated in 2019 to determine how long an individual currently at age 60 will continue to experience good health (WHO, 2022). An additional 16.4 years was average, with males having an additional 15.6 years and females an additional 17.1 years. Looking at the years 2007–2009, the highest HLE was observed in Hawaii with 16.2 years of continued good health (CDC, 2013). Overall, the lowest was among southern states. Females had a greater HLE than males at age 65 years in every state and DC. HLE was greater for whites than for blacks in DC and all states from which data were available, except in Nevada and New Mexico.

Figure \(\PageIndex{7}\): The health and vigor of the candidates are issues in the presidential election. But what does 70 really look like for ordinary Americans who aren't running for president? And what health markers are good at other decades?. ( source)

Children born in America today may be the first generation to have a shorter life span than their parents. Much of this decline has been attributed to the increase in sedentary lifestyle and obesity. Since 1980, the obesity rate for children between 2 and 19 years old has tripled, as 20.5% of children were obese in 2014 compared with 5% in 1980 (American Medical Association, 2016). Obesity in children is associated with many health problems, including high blood pressure, type 2 diabetes, elevated blood cholesterol levels, and psychological concerns including low self-esteem, negative body image and depression. Excess weight is associated with an earlier risk of obesity-related diseases and death. In 2007, former Surgeon General Richard Carmona stated, "Because of the increasing rates of obesity, unhealthy eating habits and physical inactivity, we may see the first generation that will be less healthy and have a shorter life expectancy than their parents" (p. 1).