Unexpectedly Intriguing!
August 11, 2008

After finding that the members of the black population of the United States over the age of 80 are far more likely to live longer than their counterparts in the white population, we wondered why the story is so different for those younger than 80. To see what we mean, let's look again at our chart showing the statistical number of years of remaining life expectancy by age and race for both the black and white populations in the United States:

We see that for every age below 80, the members of the black population in the U.S. are far less likely to live as long as the same-aged members of the white population, while those individuals who reach the age of 80 can expect to live longer. We also see that the gap is fairly substantial. According to Table A in the United States Life Tables, 2004, at birth, a member of the black population has a 50% chance of living at least 73.1 years, while a member of the white population can reasonably expect to live 78.3 years, a difference of 5.2 years. That gap slowly declines with increasing age and is largely erased somewhere between the ages of 75 and 80. After the age of 80, the surviving members of the black population can expect to live longer than their peers in the white population of the U.S.

### The Percentages of Survivors

From here, it makes sense to go back to the life tables to more directly compare the two populations. More specifically, we went to Table B, which shows the survivorship of each population, or rather, the statistical number of people for each 100,000 born alive within each group who reach a given age. We converted that statistical number into a percentage and charted the differences between these two racial groups:

We see that the gap between the percentage of surviving members of each population starts out small through Age 20, becomes progressively larger until between Age 75 and 80, then difference between the percentage of survivors for each group shrinks dramatically until matching up with each other around Age 100.

To see this gap better throughout all these ages, we subtracted the percentage of surviving members of the black population from the percentage of surviving members of the white population. Our results are plotted below:

Here, we see some things we expect, and some things we didn't. First, we see that roughly 1% of the black population who are born alive don't survive their first year of life. This corresponds with a higher rate of infant mortality that has been long established for the black population.

Then we see something that we didn't expect to see. From age 1 through 20, there is no significant increase in mortality for the black population with respect to that of the white population. This outcome is evident in the flatness of the curve throughout these ages. We should also note that if not for the higher rate of infant mortality for the black population, the number of surviving members for each 100,000 born alive would be nearly identical to that of the white population through the age of 20.

We then return to what we did expect to see. For the ages of 20 through the mid-70s, we see that the members of the black population are much less likely to survive than the members of the white population. The peak of the discrepancy between the percentage of surivivors of equal sized populations of each race appears to peak at an age of 78 before rapidly disappearing - a consequence of the higher life expectancies that the members of the black population have compared to their white peers above this age.

So much so that by Age 100, the number of blacks surviving to the century mark would outnumber their white counterparts if the nation were 50% white and 50% black.

Building on our previous remarks regarding the higher life expectancies of those in the black population over the age of 80 compared to their white peers, if the racial prejudice of the majority white population toward the minority black population were the primary driver of the difference between the life expectancies and survivorship of the members of the black and white populations of the U.S., it seems exceptionally odd that the black population's children and teenagers are so evidently unaffected by it, while the most elderly are likewise unaffected by it. After all, why would racism play favorites by age group?

Our preliminary conclusion is that something else must be at work here. Something else better accounts for the greater mortality of the black population between the ages of 20 and 80, while also accounting for the similar mortality of the Age 1-20 group and the lesser mortality of those over Age 80.

### More Pieces of the Puzzle

As if the differences between the white population and black population of the U.S. weren't enough, there are also differences in life expectancies between different groups within the black population itself! (We're going to avoid the difference between men and women for as long as we can help it - we've opened a big enough can of worms!)

For example, foreign-born blacks who immigrate to the United States tend to live much longer than blacks born in the U.S. - here's the relevant information from the background for Health, Life Expectancy, and Mortality Patterns Among Immigrant Populations in the United States, a 2004 study by the National Institute of Health's Gopal K. Singh and Barry A. Miller:

Compared to their US-born counterparts, black immigrant men and women had, respectively, 9.4 and 7.8 years longer life expectancy.

The increased life expectancy for immigrants comes despite higher levels of poverty compared to the native-born population:

The study reviewed millions of death and health records from 1986-94. Though the numbers are old, more limited studies of recent data suggest the same patterns hold true, although life expectancy is generally rising.

The records showed the average American-born black man could expect to reach 64, while a black man born overseas would likely live beyond 73 if he immigrated. In the case of an African-born man remaining in his homeland, he might well have died before his 50th birthday.

Perhaps most astonishing is that immigrants outlive the U.S.-born population even though they're more likely to be poor and less likely to see a doctor, often a prescription for a shorter life.

Meanwhile, where blacks live within the United States would appear to have a dramatic effect upon their life expectancy. Blacks living in urban areas have a disproportionately high mortality rate as compared to their suburban and rural peers. A 2004 University of Michigan study led by Arline T. Geronimus into Urban/Rural Differences in Excess Mortality Among High Poverty Populations: Evidence from the Harlem Health Survey and Pitt County Hypertension Study outlines some unexpected differences (emphasis ours):

As shown in Table 1, we also found that despite very high poverty rates, African American residents in rural areas did not share the highly disadvantageous mortality profiles of their urban peers. Indeed, they fared almost as well as blacks nationwide. For example, relative to white men nationwide aged 15-65 in 1990, the excess death rate per 100,000 population for black men nationwide was 374; in a rural Delta Louisiana population with a 47% poverty rate it was 391; whereas in Harlem (with a 43% poverty rate), it was 1,296. For black women residents the excess death rates in 1990 were 217 nationwide, 249 in Delta Louisiana, and 534 in Harlem (see Geronimus et al. 1996, 1999, for similar findings for a broader range of local populations). Moreover, in analyses comparing 1980 and 1990 mortality data for the same local areas, we found that the urban/rural divide increased substantially over the decade because increases in excess deaths were much higher in the urban compared to the rural areas (Geronimus et al. 1999). This finding was most pronounced among men, and was largely accounted for by deaths attributed to chronic disease. For example, over the 1980s excess deaths attributed to circulatory disease or cancer each doubled among young and middle-aged Harlem men.

And so we have our first clues as to where we're going next.

### Where We're Going Next

The evidence suggests to us that the observed differences in life expectancies between the black population and the white population in the U.S. are much more likely explained by chronic health conditions than racism. In our next stop, we'll examine just what medical conditions are robbing the black population of a longer lifespan.

After that, we'll discuss how a number of what we're going to call African curses and blessings are at play in the black population, and how a disease that kills millions in Africa, but hardly any in America, might open the door to erasing the gap in life expectancies between blacks and whites in the United States.

Ultimately, we'll offer a testable hypothesis that suggests that just a handful of comparatively simple factors explain nearly all the discrepancies between the documented life expectancies for all the groups we identified in this post. Moreover, we'll point to a seemingly simple and inexpensive solution that that might go a long way toward eliminating most of the observed disparities in the life expectancies between the black and white populations of the United States.

We say "seemingly simple" since the solution is one that the U.S. government has already provided, but which turns out to be virtually ineffective for a very large portion of the black population in the U.S. We'll explain why and then we'll point to more effective solutions already widely available in the market.

Somehow or another, we'll also figure out how to fit cattle into the picture as well, as they play a remarkably significant role in the whole thing.

We never said we weren't ambitious! We may be right or we may be wrong, but that's for real science to settle....

### All the Posts in the Series

For reference, here are all of the posts in our series covering the racial disparity in life expectancies in the United States:

Blacks Living Longer Than Whites

The post that started the whole thing! We were surprised to find that blacks over the age of 80 had longer remaining life expectancies than whites of the same ages in the U.S. We also used the opportunity to ridicule some pretty blatant rent-seeking behavior on the part of researchers seeking funding for their work.

Erasing the Gap in Racial Life Expectancies

We revisited the life expectancy figures between blacks and whites and took a closer look at the underlying data, which allowed us to reject racism as an explanation for what we observed. We also began asking "why this, but not this?" in comparing not just the survivorship of the black and white populations of the United States, but urban vs rural blacks, immigrant vs native-born blacks, and the effect of older vs younger mothers for African American infant mortality.

The Disproportionate Killers

You can't address racial disparities in life expectancies unless you know what chronic health conditions disproportionately affect the black population of the United States compared to other racial or ethic groups.

African Blessings, African Curses

Chronic diseases often have a very strong genetic or heredity component in determining who is vulnerable to them. In this post, we explored the idea that what doesn't kill you either softens you up for what will or makes you more vulnerable to other health hazards in comparing the black population of the United States to sub-Saharan Africans who share much the same genetic anthropology, while also discovering very recent research whose results potentially explain why all peoples of African descent are more vulnerable to the things that disproportionately kill African Americans.

A Seemingly Simple Solution

Does a chronic vitamin deficiency explain why the disparities between black and white life expectancies in the U.S.? We explore this possibility and why it may not as easy to address as you might think on first glance, as well as how individual African Americans might do so successfully.

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