The latest paper linking poor health outcomes in black Americans to past racial injustices has come under scrutiny from independent experts.
“Historical slavery predicts contemporary disparities in mortality between Black and White Americans,” claims a paper this summer in the Proceedings of the National Academy of Sciences.
The authors argue “[c]ounties with greater reliance on slavery in 1860 have higher contemporary mortality rates for Black Americans but lower rates for White Americans.”
Researchers, led by University of California Berkeley Professor Manuel Galvan, did not look at the actual number of slaves. Rather, they used the “cotton suitability” of soil as a proxy.
This is one of the key issues with the study, however, according to experts from Do No Harm.
Scholars Ian Kingsbury and Jay Greene wrote in a fresh analysis on Monday:
If it seems hard to believe that slavery in 1860 is killing black people today, that’s because these findings are simply not credible. A careful examination of the authors’ own results reveals that variation in modern health outcomes is caused by current health practices and behaviors and not by the enduring legacy of slavery.
The researchers with the medical reform group criticized the authors and the journal for ignoring that soil health is likely a confounding variable that would explain later health problems in the regions studies.
They wrote:
The authors, and apparently the reviewers and editors at PNAS, must have been so attracted to the conclusion of this study that they failed to devote any time to considering why it is not “obvious” that soil properties couldn’t influence modern health other than through the effects of slavery. In fact, it should be fairly obvious that the favorable soil conditions for the production of cotton would continue to shape economic arrangements and migration patterns in these areas for many years, with direct implications for health disparities.
Because the land was suitable for cotton, and because a railroad infrastructure had been built for bringing the crop to ports, there were reasons to continue growing and exporting it after slavery ended. Without enslaved labor to grow the cotton, cotton production turned to sharecropping. About two-thirds of sharecroppers were white, and about one-third were black, but all were very poor and, relatedly, had weak health outcomes.
Greene and Kingsbury also note that while black mortality rates have historically been higher than white Americans, both groups have seen a significant decrease in the past 120 years. In other words, black Americans are much better off now than they were in 1940, 1960, and 1980.
“Just because researchers use an instrument variable and declare that they cannot think of another mechanism by which cotton suitability might contribute to health disparities other than through the legacy of slavery,” Greene and Kingsbury wrote, “that doesn’t mean that they have demonstrated a causal relationship.”
