Imagine two neighbors, both in their mid-to-late 80s. One is Black and the other is white. Which one might have a better chance of reaching 100 years old?
Conventional wisdom would suggest the white octogenarian would have a leg up on that climb to 100, because of the mountains of research showing better access to health care and other opportunities for white Americans. Additionally, Black people in the United States generally have higher death rates at younger ages.
But a novel new study from Boston and Canadian researchers adds important depth to an unusual reversal of that death equation — that Black octogenarians in the United States have significantly better odds of living to 100 than their white counterparts. And those odds get better with age.
The study, published Wednesday in the Journal of Internal Medicine, found that white women at 80 years old have a 4 percent chance of living to 100, while the odds are 6 percent for Black women. By the time they hit 90, that stretches to 9 percent for white women — and 13 percent for Black women.
The survival odds are lower for males, but the pattern is the same; a roughly 3 percent chance for Black men at age 80 to make it to 100, but just 2 percent for white men. By age 90, it was 5 percent for white men and 9 percent for Black men.
The researchers also studied survival patterns among Hispanics and Asian Americans and both showed even better longevity odds. They found a roughly 8 percent chance for Hispanic women, and 10 percent for Asian women to make it to 100 from age 80. That expanded to roughly 15 percent for both groups at 90. The researchers did not have sufficient data to analyze survival patterns for American Indian or Alaska Native populations.
“There is a tremendous amount to be learned from these different groups in what they have in common and don’t have in common,” said study coauthor Dr. Tom Perls, professor of medicine and geriatrics at Boston University’s school of medicine and director of the New England Centenarian Study.
“By studying this, we will solve this puzzle, which is, what are the environmental and genetic underpinnings of exceptional longevity and healthy aging,” Perls said.
The study also acknowledged the significant disparities between Black and white populations at birth, showing a life expectancy of 78 years in 2019 for Black people, but 81 for whites. Hispanic and Asian American life expectancies were even greater, with Hispanics projected to live to 84 and Asians to 87.
But it also dramatically highlights a long-debated phenomenon known as the Black-white mortality crossover: Up until roughly their mid-80s, Black people have higher mortality rates than whites, but then decline in comparison to whites, and their life expectancy becomes greater.
The phenomenon was first noted by researchers more than a century ago, and it has been debated and investigated ever since. Skeptics have long said that the “crossover” was not real, and that the phenomenon of Black people outliving whites in their later years was merely a reflection of inaccurate birth and death records, especially from decades ago for Black people.
That concern remains but has eased as record-keeping has improved. The data Perls and his coauthor, Nadine Ouellette, an associate demography professor at the University of Montreal, used to calculate survival rates came from the US National Center for Health Statistics and are considered reliable.
Today, most researchers say the crossover phenomenon likely reflects what they call “select survival,” meaning that many Black people die at younger ages because of social, economic, and other disadvantages, leaving the hardiest to live on. Or, as Ouellette puts it: “Those who survived to these great old ages are probably the most robust and this is what we are seeing in terms of survival.”
In their study, the Black-white crossover occurred between the ages of 86 and 88, depending on gender, and persisted to age 100 and beyond.
Researchers not involved in the study said it is the first to demonstrate the Black-white crossover continued a decade longer than previous studies have shown.
But it wasn’t just the persistent Black-white crossover that was intriguing, they said. The study also demonstrated that at age 100, estimated additional life expectancy for the Black population was similar to that of the Hispanic and Asian populations, and all three were significantly greater than for the white population.
“It’s interesting how all the minority groups were together in terms of their probability of survival. They are very similar to each other, and all of them together are very different than the white population, and that’s news,” said Mark Hayward, a sociology professor at the University of Texas at Austin who studies population health and mortality rates of older adults.
Those greater odds of survival, even at age 100, translated to a life expectancy that was roughly six months longer for Black people compared to white people in 2019, the study showed. And for the Hispanic and Asian populations, it added up to about four to five additional months, compared to the white population.
Perhaps one of the most dramatic illustrations of Black longevity came in the life of Herlda Senhouse of Wellesley, who died last month at age 113. A petite woman with a firecracker personality, she was the second oldest person in the United States whose age was verified. The oldest is Naomi Whitehead, a 114-year-old in Pennsylvania, who is also Black.
The research by Perls and Ouellette did not try to answer the question of why Black, Hispanic, and Asian-American populations have longer life expectancies once they hit old age.
But the researchers noted other ongoing work by Perls at the New England Centenarian Study has demonstrated that combinations of certain genes appear to play an increasingly stronger role in survival to very old ages.
Even so, as the researchers point out, behavariol and environmental factors are the main drivers of mortality rates up to about age 90. For example, studies of Seventh Day Adventists in California, whose members typically don’t smoke, showed their life expectancies were roughly four to seven years longer than the California population as a whole. And Adventists who were vegetarian, did not smoke, engaged in high physical activity, and were not overweight lived roughly 10 years longer than their white California peers.
Lowell Taylor, an economics professor at Carnegie Mellon University who has studied the Black-white crossover phenomenon, said the Perls and Ouellette study will help researchers and the general public focus on similar ways to live better longer.
“Learning about the forces that shape mortality at a very old age would give us really good ideas about what we theoretically can do ourselves to make us have longevity,” Taylor said.
Kyriakos Markides, a pioneering sociology professor at the University of Texas Medical Branch, said the new study confirms and adds to the research he has done. Markides is credited with coining the term the ‘Hispanic paradox,’ where Hispanic people in the United States live longer than white people, despite generally lower socioeconomic levels and health-care access.
Back in 1984, Markides coauthored a study about the Black-white crossover and found the phenomenon in the United States then happened at around age 75 — when overall life expectancies were lower. The study suggested that having a greater proportion of Black people who are more robust at very old ages, compared to white people, might have explained the lower rates of suicide among older Black people and fewer living in nursing homes at that time.
But Markides notes that often overlooked in discussions of the Black-white crossover are the great disadvantages Black populations often face earlier in life, hurdles that often lead to proportionately more deaths at younger ages, compared to white people.
“When you get to be very old,” he said, “and you enjoy certain advantages, it’s nice to see.”
Kay Lazar can be reached at kay.lazar@globe.com Follow her @GlobeKayLazar.
