The Journey of Humanity by Oded Galor: A Review Essay

The laws of history have nothing in common with a pedantic schematism. (28) Unified growth theory captures the journey humanity over entire course since emergence Homo Sapiens Africa 500,000 years ago. It identifies and traces forces that governed process development during Malthusian epoch, eventually triggering phase transition which human species escaped from this poverty trap into an era sustained growth. insights are essential for understanding its entirety, hurdles faced by poorer economies today their stagnation to growth, origins great divergence wealth nations past centuries, fingerprints ancient fate nations. (45) As such, Journey Humanity joins such celebrated large-scale histories as Guns, Germs, Steel (1997) Jared Diamond Why Nations Fail (2012) Daron Acemoglu James Robinson. is arguably more ambitious than either respect breadth it attempts present interpret. In essay, I assess terms author's contributions study development; other words, focus on second level at one can read book. First, consider what assessment should be made about substantive novelty Galor's approach long-run dynamics—the claim genetic diversity fundamental “deep root” contemporary differences economic across world. Second, overall contribution unified beyond set time– context-specific theories constitute current economics. serious reservations arguments role diversity1 well value everything whose objective interpret full development. conceptual framework devised few decades was inspired mathematical field bifurcation theory, demonstrates how, certain threshold, minor alterations single factor may generate sudden dramatic transformation behaviour complex dynamic systems. (46) For Galor (e.g., Weil 2000; Moav 2004), key bifurcations occur evolution technology capital. Incentives families invest capital depend state society. This depends initially size population, underlying idea larger populations beget greater ideas. At some point, population sets motion dynamics. Why? Higher levels induce higher technology. turn but effect attenuated increased incentives part parents children's Together, understand transitions regime growing stabilizing allow per capita output post-Malthusian autocatalysis via interplay ideas accumulation lies foundations endogenous Paul Romer's Nobel Prize-winning (1986, 1990) social increasing returns scale Lucas (1988), focuses source returns. involve linking ways nonlinear systems provide quantitative properties my judgment, important new insights. approach, sketched out, addresses question dynamics escape trap. call methodological ultimately relies features embed standard behavioral assumptions link technological change, size, investments his framework. no disparagement. replete behaviors, documented (2005). Identifying types models best capture empirics nonlinearity enormously important. That said, when class enhances where does not. There longstanding debates demography literature contrast norms versus conventional explanations fertility dynamics; Lesthaege Surkyn (1988) remain invaluable overview. These authors “Western ideational change…the processes secularization individuation” (8) timing view supported many studies; Coale Watkins (1986) classic topic, Blanc (2022) interesting recent analysis providing evidence 18th French lowering fertility. Formal those has developed understood elucidating phenomena particular time spatial scale, is, implicitly aggregates swaths space smooths out phenomenon under study. known coarse graining physics tool broad However, aggregation mask mechanisms another. Abstractions efforts wide ranges suffer possible danger obscuring too much abstracting away factors interest universality.2 return below import cost. receives attention Humanity, contrast, problematic. involves major reason heterogeneity Ashraf (2013) argument. basic there exists optimal If high, then trust, cooperation, production public goods inhibited. low, homogeneity skills perspectives works against creativity innovation. Europe economically outperformed parts world, particular, indigenous Americas because possessed fortuitous intermediate diversity, while African inhibited lower diversity. They migration distance ultimate mechanism. How do justify claim? Much derived regressions project statistical measure construct year synthetic measures country-specific ancestral based calculations various ethnic groups combined data flows these 1500. further use migratory instrumental variable account endogeneity opposed deep roots. empirical claims paper challenged three distinct levels. surprisingly mute marginal explanatory power measures; calculation appears online Appendix presents adjusted R2 values 0.03 square, hardly power. matters considers integrating theory. considerable worry errors reported. Focusing most regression paper, uses sample 143 countries determine between development, reported errors. takes very heroic assumption uncorrelatedness regard associated parameter estimates credible.3 universal problem cross-country regressions, purchase here paper's choices control variables. choose controls candidates roots institutional quality geography. they ignore frequency variables, monetary fiscal regimes, exhibit correlations countries. omitted vast range determinants implication induced dependences model theoretical considerations been shown matter. Kelly (2019) seminal unobserved studies. He shows Ashraf–Galor, 2000 income correction correlation doubles estimates. But note argument general country-level distance. intra-population we employ interpreted proxy (i.e., correlated summary measure) amongst individuals myriad observable unobservable personal traits physiological, behavioral, socially-constructed, or otherwise. (2) noted critique, given fact proxies measures. finding γ ≠ 0 $\gamma \ne 0$ treated explanation R i ${R_i}$ constitutes ω. Galor, country's population. fallen disrepute? criticisms matter here. not adequately address uncertainty appropriate choice variables (1). contexts science consensus additional need included consider. Durlauf, Johnson, Temple (2005) found, 140 different had appeared up survey. were all, ex ante, theoretically plausible. Further, all logically compatible each other, so presence did imply another consequences well.5 investigate robustness findings “institutional, cultural, geographical development” (37, Table 7). argued above, investigation ignored except schooling 7 Column 8). relative literature, exploration misses candidate basis concluding robust mechanisms. might respond estimating reduced form system high-frequency really answer, reasons suggested above. Any assumed caused hard justify. Why, example, policies countries, presumably aspects, anything distance, spatially variable? (As algebraic proposition, omitting course, preserve unbiasedness parameters orthogonality content must credible.) uncover sense without determining relationship chosen (1) assume linearity additively separability functional naturally arise vantage point theories. Starting linearity, predicated Africa, leads squares otherwise linear regression. omits nonlinearity. specification used work nonlinearities themselves. By this, mean function relate GDP capita, levels, like values. debating point. Bernard Durlauf (1996) Kourtellos, Tan's intergenerational mobility analyses, failure produce deeply misleading conclusions To impact type nonlinearity, suppose setting initial conditions pre-1500. led equilibria process; multiplicity interpretation poverty, middle income, affluence traps case, contemporaneous disparities se, entirely conditions. story Galor. A complementary critique occurs interactions additive separability. Tan (2010) demonstrating theories; justified and, shows, lead ignored. indicate why presented untenable assumption. Would diversity's survive considering alternative specifications? impossible know. Third, Equation assumes constant coefficients imposition concerning predictive effects complex, heterogeneous units. continent-level fixed effects, clear adequate.6 continents, intercepts not, adding continental dummies? continent correct thinking heterogeneity? Scientific7 Industrial Revolutions uniformly Europe. country heterogeneity, if dummy appropriate? again adds dummies World Bank region finer grained original finds these, conjunction adjustments robustness, reduce 30 percent originally Important advances research last two addressed issues uncertainty, forms, heterogeneity.8 With references Fernandez, Ley, (2001), using Bayesian methods, 41 predictors conclude only four posterior inclusion probabilities prior assigned them. Sala-i-Martin, Doppelhofer, Miller (2004) Bayesian-frequentist hybrid method identify that, starting 67 18 robustly Subsequent proven consistent findings. here? structure equation, applies this. reference Johnson (1995) early example provided clubs behavior. incomes literacy rates sort models, distinguished sensitivities physical accumulation. Later developments include Canova Pittau, Zelli, demonstrate formulations. undermines specifications considered means projecting (one square level) onto observations Thus, tools available could problems described. deserve criticism failing limits analyses previous work. From believe anywhere near strong enough treating compelling explanation. Therefore, genetics flawed sustain root (migratory distance) explains density far future, 1500 2000. strength therefore determined extent credibly argue uncorrelated event interest. My uniquely difficult context number required reveal K ${R_{iK}}$ thus T. Whether emerging themselves influenced , determinant ω T ${\omega _{iT}}$ . clear, emerges every period necessary issue inequalities fixed, growing. One answer give he searching rather proximate explanations. What mean? possibility looking − $T - K$ so, temporally less distant cannot speak proposes explain importance conflict emerge after K, diversity/development affects factors, definition model. requires define causes sufficiently so. final regressions. Suppose orthogonal j ? ${R_{ij}}?$ Since facts geography affect see how make post ${R_{ij}}$ Formally, identification cov ( ) = ${\mathop{\rm cov}} {{R_{iK}},{R_{ij}}} < ≤ $K \le T$ will typically E $E( {{\mathop{\rm )} nonstandard formulation condition regression, seems natural context. researcher able argue, considerations, total subsequent positive negative expected others cases positively negatively correlated. thing being realized zero light commonalities exist. farther back goes time, credible modeling intervening factors. Deep problems. Such Empirical comes critiques directly apply solely evidence. Scientific evaluation “inference explanation,” cf. Lipton (2004), also abduction, sources integrated decision accept explanation, geography, root, like. Judgments invariably needed abduct conclusions.9 nature science. case stronger evidentiary bases. colonial institutions subject Acemoglu, Robinson (2001). includes settler morality heterogeneity. instrument generated controversy; Albouy rejoinder (2012). regressor, albeit given, horizons studied. institutions/development body bring bear.10 buttress claims. decades, physicists attempted devise “Theory Everything” would coherent universe, …Their driven conviction systematic accurate aspects reality rooted capable explaining phenomena; any partial inherently incomplete…The fuelled similar drives globally fragile incomplete unless reflect primary driving behind merely isolated periods. (44) While rhetorical power, remarkably superior specific temporal, spatial, cultural contexts. On own terms, defense difference unifications with, say model, unification proposes. unifies relations elementary particles nature. concatenation true conflict. Does change thinks conflict? behavior large particles, turns simple extrapolation particles. Instead, complexity appear, behaviors think other…The ability start reconstruct universe. stage laws, concepts, generalizations necessary. (393) reasoning applicable argues, following (2005, 2012, 2019), 500 due societies. plausibly institutions, ideology, religion, emergent Their affected whether append Genetic component latter Nothing lost, growth/institutions institutions.11 critical juncture concentrated macro episode innovation generates enduring legacy. (34) argues junctures both historical contingency. develops emphasizes (compared diversity) determinant, elucidates contingencies, ideologies. emergence? Statistical mechanics motivated Anderson essay separate property called transitions. qualitative around values, degree interdependence elements magnitudes system. contingencies shocks cause rapid discontinuous changes persist causes—institutions radically contingency Enlightenment. emergent, help influence trajectories.13 response presumably, goal develop time- context-specific—hence assertion “fragile” “isolated periods.” simply incorrect. theories, provides disjoint periods know conceptually contexts, diminish domains. No physicist relativity quantum mechanics. grow increase collective knowledge environments, direct toward productive e