IQ externalities of low-skilled migration

Low-skilled immigration can impose measurable social costs because average cognitive-related traits (crime, trust, cooperation, economic literacy) generate positive externalities; large inflows of low-skilled migrants may therefore reduce societal welfare even if GDP rises. The claim is empirical and depends on the size, composition, and local concentration of migrants rather than abstract long-run gains. — If true, this reframes immigration policy debates from simple fiscal/market effects toward aggregate social-capital and cognitive externalities, changing how policymakers weigh admission and integration strategies.