Roland Fryer has won the John Bates Clark medal for the top economist under 40.
I’ve paid attention to some of his papers that impinge on biology, even corresponded with him. In one, he argued that higher risk for cardiovascular disease among American blacks was due to genetic factors, those resulting from selection for salt-sensitivity in the Middle Passage, the risky journey to America.
There’s nothing wrong with looking for genetic factors as a possible explanation (or partial explanation) of such health differences, but it’s not necessarily easy to come up with correct answers, least of all when you don’t know anything about the subject – don’t know anything about biochemistry or medicine or natural selection. Which is the default state of humanity, of course – and of economists.
There are black-white genetic differences in genes involved in holding onto salt and water, and that’s undoubtedly a product of selection – but you see those same variants in Africans. It’s not something that showed up in 1750.
The death rate in the Middle Passage was about 15%, during the period that most of the ancestors of American blacks came across. A lot of those deaths were due to diarrheal disease, but there is no reason to think salt-sensitivity is the overwhelmingly dominant factor that determines survival in such cases – obviously the immune system must also matter, for example. There is certainly no evidence that salt-sensitivity is even the main factor in determining survival in such cases, although it might be. And since there were other causes of death there, such as scurvy and smallpox, it couldn’t have been all-important.
Moreover, it is almost impossible to cause a significant genetic change in one generation*, unless the selective factor wipes out something like the least resistant 95% of the population. I told Fryer this – worked out an example using the breeder’s equation, plausible values of heritability, a favorable (and unrealistic) estimate of the importance of salt retention, reasonable estimates of mortality on those ships – there was no way anything significant would happen. He didn’t make use of the breeder’s equation, but it can’t be that he never heard of it, because I told him.
He mentioned a case in which researchers successfully bred salt-sensitive rats in three generations, with noticeable change by the second generation – but with this was done by founding one line with the two most salt-sensitive rats (2 out of 47) and the other with the two least salt-sensitive rats. That rat experiment was the equivalent of 95% casualties for three generations , all strictly due to salt sensitivity – pretty different from 15% casualties for one generation that are maybe kind-sorta influenced by salt sensitivity. Consider also that they are comparing one line strongly selected for salt-sensitivity with another strongly selected for salt-insensitivity, selection was a minimum of 60 times stronger in the rat experiment than in the Middle Passage.
There’s no chance that salt-sensitivity in African-Americans is a product of selection in the Middle Passage.
In another paper, Fryer and Leavitt looked at intelligence in children aged 8 to 12 months. They find only minor racial differences in test outcomes. which proves..??? At that point you’re testing motor skills or something – anything like an IQ test is impossible. Black kids are somewhat precocious in motor skills compared to whites: on average they walk about a month earlier, East Asians about a month later. But chimps at age one will outperform all humans, while gazelles can run 15 minutes after birth. All which proves nothing at all. That first paper is wrong. This paper is … not even wrong.
Well, maybe the papers I have not read are high-quality. There’s a rule, I think: when someone is egregiously wrong on all the things you know anything about, he must be damn good on everything else.
* the next person who talks about how much people living in slum conditions in the US over the last couple of generations must have been selected for X, where X is anything at all, WILL BE BANNED