From a response to a different attack on Lynn and Vanhanen:
Right. As I pointed out in my VDARE.com review in 2002, Lynn and Vanhanen's finding of an average IQ of 70 in black Africa is strong evidence in favor of the nurture position that a better environment can raise IQs, because African Americans, who appear to be about 4/5th black, score 15 points higher.
. . .
Moreover, there are still some low-hanging fruits where 3rd World countries would benefit from public health programs that succeeded in the U.S. in the first half of the 20th Century in boosting IQ directly or or in boosting mental energy. Fortifying salt with iodine eliminated the medical syndrome cretinism. while fortifying wheat with iron also eliminated an IQ-sapping medical condition. The Rockefeller Foundation's war on hookwarm greatly benefited the physical and economic energy of Southerners by ridding them of a parasite.
I haven't studied these issues, but I will note that Steve Sailor and VDARE.com are considered by many people to be racist bigots. Here, for example, is a VDARE article defending white supremacy:
White supremacy, in the sense of a society in which key decisions are made by white Europeans, is one of the better arrangements History has come up with.
This doesn't mean that Sailor's claims in the article you quoted are false, but it might mean that Sailor is unusually susceptible to motivated cognition in a particular direction when it comes to racial issue...
This is interesting, I wonder if there's anything to it: International variation in IQ – the role of parasites (paper) by Christopher Hassall of U. Carleton.
It strikes me as the sort of thing that could be as big an issue as lead in the environment. Raise the sanity waterline: improve health!