Abstract
Previous research indicates that the typical increase in IQ during childhood is greater in European countries than in Arab countries. A systematic literature review of age-dependent IQ in Arab countries is conducted, yielding relevant studies for 12 countries that fulfil the inclusion criteria. In almost all of these studies, Arab children exhibit an age-dependent IQ decline relative to Caucasian children, from 5 to about 12years of age in particular. We term this phenomenon the Simber Effect. We propose two non-exclusive explanations. (1) The Flynn Effect is less intense in Arab countries because of localised differences, including poorer education quality and greater religiosity. (2) Those from Arab countries follow a faster Life History Strategy than Europeans, for environmental and possibly genetic reasons. Either way, the Simber Effect may amount to a Wilson Effect, meaning that the impact of genetic IQ increases with age.
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•A systematic review of child IQ in Arab countries is presented.•IQ of Arab children declines with age relative to Greenwich IQ and other European IQs.•Arab-country educational standards likely a significant cause.•Differences in Life History strategy may help to explain results.