I don't for a second belief that the mean IQ in Equitorial Guinea is only 59, but it's certainly possible to have a society where half the people have a reasona

I don't for a second belief that the mean IQ in Equitorial Guinea is only 59, but it's certainly possible to have a society where half the people have a reasonably functional level of intelligence, but due to some debilitating recessive genetic disorder have a huge population of disabled individual who are cared for by the unaffected part of the population and who even supported in their moral right to mate and produce children -- perhaps even exploited as manual laborers.