The present research found that the Muslim country mean IQ of 81 is half a standard deviation below the mean IQ of non-Muslim nations and is not related to strength of Muslim culture as defined by the percentage of Muslims in the country. The mean IQ of 84 in Arab countries is not associated with per capita income and is incompatible with the intellectual achievements of the golden age of the Muslim Empire. Possible explanations for this decline include hybridization with sub-Saharan Africans, dysgenic decrease in the more educated Muslims employing birth control as suggested by Meisenberg, the Muslim religion not fostering critical thinking, and the intellectual contributions being both exaggerated and made by non-Muslims.
[Donald I Templer. The Comparison of Mean IQ in Muslim and Non-Muslim Countries. Mankind Quarterly. Washington: Spring 2010. Vol. 50, Iss. 3; pg. 188, 22 pgs]
IQ in Muslim and Non-Muslim Countries
Another abstract from Mankind Quarterly: