Marc Klemp

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.

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.

This chapter explores how evolutionary processes and population dynamics have influenced the long-term economic development of nations, examining factors such as genetic diversity, geographical conditions, and historical migration patterns.

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.

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.

Media: VoxEU

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.

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.

Building on prior evidence for parity-dependent birth spacing, we find further indications of within-marriage fertility control in 17th–19th century England. This research adds to the understanding of pre-transitional demographic behaviors preceding the demographic revolution.

Using family reconstitution data for England (1540-1850), we show that worsening economic conditions were associated with increased birth spacing. This relationship is stronger after 1750, and concentrated among poorer families, suggesting deliberate fertility control was a preventive check used by families to manage economic stress.

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.

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.

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.

A two-sector Malthusian model is estimated using cointegration and error-correction methods with data for pre-industrial England. Fertility responds positively to agricultural wages, and the estimated effect of real agricultural prices is nonnegative. The results support the Malthusian account of economic and demographic stagnation before industrialization.

This study analyzes prescription, diagnosis, and operation data to accurately infer glaucoma status in a large Danish population dataset, providing a valuable method for identifying glaucoma cases in medical research.

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 similar to controls.

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.

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.

Media: Eurotimes

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.

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.

Proposes that population diversity, shaped by the exodus of Homo sapiens from Africa, contributed to autocratic institutions historically. Diversity can enhance productivity but also fosters scope for domination, with lasting implications for modern political systems.

Media: New York Times

We document a hump-shaped relationship between within-group genetic diversity and productivity, capturing both the innovative benefits and frictions that diversity can produce. Cross-ethnic data at subnational levels confirm the trade-off across economic outcomes.

This Stata command implements the augmented IV estimator developed in our JDE paper "Historical Instruments and Contemporary Endogenous Regressors." It addresses limitations of conventional IV regression when measuring persistent effects with historical instruments by accounting for the persistence of endogenous factors over time.

This program visualizes the phase space of Overlapping Generations (OLG) models, including scenarios with multiple intertemporal equilibria. It does not compute full transition paths, but highlights equilibria and dynamic behaviors.