From the top comment:

Yeah, I really wouldn't trust how that book [by Richard Lynn] picks its data. As stated in "A systematic literature review of the average IQ of sub-Saharan Africans":

For instance, Lynn and Vanhanen (2006) accorded a national IQ of 69 to Nigeria on the basis of three samples (Fahrmeier, 1975; Ferron, 1965; Wober, 1969), but they did not consider other relevant published studies that indicated that average IQ in Nigeria is considerably higher than 70 (Maqsud, 1980a, b; Nenty & Dinero, 1981; Okunrotifa, 1976). As Lynn rightly remarked during the 2006 conference of the International Society for Intelligence Research (ISIR), performing a literature review involves making a lot of choices. Nonetheless, an important drawback of Lynn (and Vanhanen)'s reviews of the literature is that they are unsystematic.

They're not the only one who find Lynn's choice of data selection suspect. Wikipedia describes him as:

Richard Lynn (20 February 1930 – July 2023) was a controversial English psychologist and self-described "scientific racist" [...] He was the editor-in-chief of Mankind Quarterly, which is commonly described as a white supremacist journal.

[From earlier in the comment] I can view an astonishing amount of publications for free through my university, but they haven't opted to include this one, weird... So should I pay money to see this "Mankind Quarterly" publication?

When I googled it I found that Mankind Quarterly includes among its founders Henry Garrett an American psychologist who testified in favor of segregated schools during Brown versus Board of Education, Corrado Gini who was president of the Italian genetics and eugenics Society in fascist Italy and Otmar Freiherr von Verschuer who was director of the Kaiser Wilhelm Institute of anthropology human heredity and eugenics in Nazi Germany. He was a member of the Nazi Party and the mentor of Josef Mengele, the physician at the Auschwitz concentration camp infamous for performing human experimentation on the prisoners during World War 2. Mengele provided for Verschuer with human remains from Auschwitz to use in his research into eugenics. [...] Something tells me it wouldn't be very EA to give money to these people.