A number of studies have shown that intelligence can be severely affected by malnutrition (Simeon & Grantham-McGregor 1990; Liu et alii 2004) and infectious diseases (Eppig, Fincher & Thornhill 2010). If this is true for modern populations, it can be assumed that it was also the case for ancient populations, such as the ancient Egyptians. Thus, in order to assess the intelligence of Egyptians, it is crucial to assess the impact of these factors on it.
A review of the literature on alimentation in ancient Egypt (Tallet 2003; Peters-Destéract 2005; Touzeau et alii 2014) reveals than the diet of most Egyptians mainly consisted of bread and vegetables. The iconography of Egyptian tombs, which portrays a cuisine in which poultry and fishes have an important place, comes from the socio-economic elite and is not representative of the Egyptian population as a whole. The consumption of meat and fish was scarce, which has an important implication: since Egyptians rarely consumed the aliments which could provide them with iron, and since iron deficiency has been identified as an important factor affecting IQ (Lynn & Harland 1998), it is very likely that this deficiency affected their intelligence in a significant way. It must be emphasized that their diet remained quite constant over 2500 years, despite considerable social, political and economic changes (Touzeau et alii 2014).
As for the diseases, the prevalence of many of them in ancient Egypt, e.g. dysentery, tuberculosis, typhus, typhoid, smallpox, malaria, and plague, is well attested (Scheidel 2001). Even though many of them might not have had a direct impact on IQ, according to the “parasite-stress hypothesis” (Eppig, Fincher & Thornhill 2010), the general level of infectious diseases may have had a negative impact on intelligence by requiring a considerable level of energy, which could therefore not be provided to the brain: “From an energetic standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks” (Eppig, Fincher & Thornhill 2010).
To summarize, one cannot accept Herodotus’ statement that Ancient Egyptians were “the healthiest of men, next to the Libyans” (Herodotus, II, 77; transl. Scheidel 2001). It is clear that the environmental conditions of Ancient Egypt, which remained quite constant over 2500 years, impaired the ancient Egyptians’ cognitive ability in a significant way. Most of them were not able to reach the full intellectual potential which their genotype would have allowed.
