Over the last two centuries, you would expect to find a direct causal link between industrialization and intelligence, as governments have introduced mass educa

Over the last two centuries, you would expect to find a direct causal link between industrialization and intelligence, as governments have introduced mass education for the first time, to create a skilled labour force. Because industrialization is also positively correlated with pollution and urbanization, especially during its first phase, you would also expect to find a long-term positive correlation between pollution and intelligence. However, if you factor out the positive effects of mass education, then you will likely find, as expected, that intelligence decreases as toxicity of the environment rises.