Marc Klemp

Abstract: This research establishes that interpersonal population diversity has been pivotal to the emergence and severity of intrasocietal conflict, measured by an exogenous variation from ancient human migration out of Africa. Mechanisms include mistrust, divergent preferences, and reduced cohesion.

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Abstract: We develop an augmented IV estimator to address time gaps between historical instruments and contemporary regressors, applying it to institutions and Protestantism. Our findings suggest somewhat smaller—but still important—long-run effects than standard estimates reveal.

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Abstract: Exploiting genealogical data for 16th–19th century England, we measure parental reproductive capacity via the interval between marriage and first birth. While higher fecundity yielded larger sibling sets, it reduced children’s socio-economic outcomes, consistent with a quantity–quality trade-off at the origin of modern economic growth.

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Abstract (English): This research provides an overview of how ancient migration from Africa 60–90 thousand years ago shaped global population diversity, influencing modern economic performance, civil conflicts, political institutions, and interpersonal trust.

Abstract (Danish): I denne artikel gennemgås, hvordan menneskets udvandring fra Afrika har påvirket den globale fordeling af befolkningsdiversitet og ført til forskelle i økonomisk udvikling, konflikt, tillid og institutioner.

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Summary: Using Brazilian data on oil reserves, we find that localities closer to oil fields enjoy higher per capita income. This positive impact is independent of oil royalties, consistent with “indirect linkage” effects rather than a straightforward resource curse.

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Abstract: Using a reconstructed genealogy of nearly half a million individuals in Quebec (1608–1800), we show that while higher fecundity led to more children, moderate fecundity maximized long-run descendants. Evolutionary forces decreased fecundity over time, suggesting an advantage for having children at an intermediate rate. Mechanisms include improved child quality and marriageability.

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Abstract: Using duration models on 15,000 families (60,000 births) in England (1540–1850), we show that couples adjusted birth intervals in response to economic conditions and existing children, implying parity-dependent birth spacing well before the demographic transition.

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Abstract: Similar to England, Denmark, Norway, and Sweden displayed a post-Malthusian phase where incomes and population grew despite diminishing returns, lending broader support to transitional post-Malthusian growth theory.

RePEc

Abstract: Linking apprenticeship records with family reconstitution data, we find that eldest sons of non-gentry were often apprenticed, implying parental choice by aptitude rather than inheritance norms. Return migration was frequent, suggesting parents anticipated direct benefits from children’s skill acquisition.

RePEc

Abstract: Individuals born during the severe 1720s English famine suffered higher mortality risks well into adulthood, suggesting a permanent negative health shock. Those born just before or after did not share this fate.

RePEc

Abstract: A cointegrated VAR approach (16th–18th century England) reveals that higher agricultural wages positively affected fertility, with a nonnegative effect from agricultural prices. This supports a standard Malthusian model, as posited by unified growth theories.

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Abstract: Investigating 545 men testing positive for anabolic steroids in Denmark, we find a 26% lower fertility rate prior to doping. However, fertility partially recovers, suggesting AS-induced infertility may be reversible. Usage of assisted reproduction and ultimate parenthood rates are comparable to controls.

Journal (Open Access)

Abstract: Analyzing 2.6 million Danes reveals that while hypertension is associated with higher glaucoma risk, antihypertensive medication reduces that risk in a causal sense. This supports a protective effect of blood pressure treatment on glaucoma onset.

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Abstract: Using EEG-based steady-state responses (SSRs) to passive audiovisual stimulation in middle-aged men, we find alpha–gamma power differences strongly correlate with intelligence. This link is robust to confounders and consistent with earlier-life IQ measurements.

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Abstract: Studying 1,444 amphetamine poisoning patients (2006–2013) vs matched controls reveals an 11% seven-year mortality vs 0.6% for controls, mostly from unnatural causes. Psychiatric disorders, HIV, hepatitis, and incarceration rates were markedly higher, damaging long-term prognosis.

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Abstract: We observe alpha–gamma band differences in visual steady-state potentials in older adults, strongly correlating with intelligence. The correlation persists when controlling for speed of processing and other factors, indicating a potential clinical tool for cognitive assessment.

Open Access