William Easterly's superb book draws on what we have learned from almost two decades of cross-country growth comparisons, providing a critical synthesis of the current state of empirical knowledge on growth. The author emphasizes policy and institution-driven incentives for growth, and also critically surveys evidence for more traditional sources of growth such as factor accumulation. Another contribution of the book is an accessible and detailed description of the vicious cycle of adjustment loans directed by the World Bank and IMF at countries that squander these resources in current consumption rather than investment, leading to stagnant growth, debt crises, debt relief and further adjustment loans.

The empirical literature on economic growth and development has moved from the study of proximate determinants to the analysis of ever deeper, more fundamental factors, rooted in long-term history. A growing body of new empirical work focuses on the measurement and estimation of the effects of historical variables on contemporary income by explicitly taking into account the ancestral composition of current populations. The evidence suggests that economic development is affected by traits that have been transmitted across generations over the very long run. This article surveys this new literature and provides a framework to discuss different channels through which intergenerationally transmitted characteristics may impact economic development, biologically (via genetic or epigenetic transmission) and culturally (via behavioral or symbolic transmission). An important issue is whether historically transmitted traits have affected development through their direct impact on productivity, or have operated indirectly as barriers to the diffusion of productivity-enhancing innovations across populations.

We find that genetic distance, a measure associated with the time elapsed since two populations' last common ancestors, has a statistically and economically significant effect on income differences across countries, even controlling for measures of geographical distance, climatic differences, transportation costs, and measures of historical, religious, and linguistic distance. We provide an economic interpretation of these findings in terms of barriers to the diffusion of development from the world technological frontier, implying that income differences should be a function of relative genetic distance from the frontier. The empirical evidence strongly supports this barriers interpretation.

We find that more closely related populations are more prone to engage in international conflict with each other. We provide an economic interpretation based on two connected mechanisms. First, more closely related groups share more similar preferences over rival goods and are thus more likely to fight over them. Second, rulers have stronger incentives to conquer populations more similar to their own, to minimize postconflict heterogeneity in preferences over government types and policies. We find support for these mechanisms using evidence on international conflicts over natural endowments and on territorial changes, including decolonization.

Several influential commentators have suggested recently that democratization in developing countries produces political instability, ethnic conflict, and poor economic outcomes. For instance, Robert D. Kaplan (2000) states that “If a society is not in reasonable health, democracy can be not only risky but disastrous” (p. 62). Fareed Zakaria (2003) points out that “although democracy has in many ways opened up African politics and brought people liberty, it has also produced a degree of chaos and instability that has actually made corruption and lawlessness worse in many countries.” Amy Chua (2003) argues that: “... in the numerous countries around the world with a market-dominant minority, ... [a]dding democracy to markets has been a recipe for insability, upheaval, and ethnic conflagration.” (p. 124).

Observed international investment positions and cross-country heterogeneity in rates of return to capital are hard to reconcile with frictionless capital markets. This article develops a theory of international capital allocation: a multi-country dynamic spatial general equilibrium model in which the entire network of cross-border investment is endogenously determined. Our model features cross-country heterogeneity in fundamental risk, a demand system for international assets, and frictions that cause segmentation in international capital markets. We measure frictions affecting international investment and apply our model to data from nearly 100 countries, using a new dataset of international capital taxes and cultural, linguistic, and geographic distances between countries (geopoliticaldistance.org). Our model performs well in reproducing the composition of international portfolios, the cross section of home bias and rates of return to capital, and other key features of international capital markets. Finally, we carry out counterfactual exercises: we show that barriers to international investment reduce world output by 7% and raise the cross-country dispersion of capital per employee, contributing in a meaningful way to global inequality.

In a world of trade restrictions, large countries enjoy economic benefits, because political boundaries determine the size of the market. Under free trade and global markets even relatively small cultural, linguistic or ethnic groups can benefit from forming small, homogeneous political jurisdictions. This paper provides a formal model of the relationship between openness and the equilibrium number and size of countries, and successfully tests two implications of the model. Firstly, the economic benefits of country size are mediated by the degree of openness to trade. Secondly, the history of nation-state creations and secessions is influenced by the trade regime.

This paper studies the evolution of sectoral concentration in relation to the level of per capita income. We show that various measures of sectoral concentration follow a U-shaped pattern across a wide variety of data sources: countries first diversify, in the sense that economic activity is spread more equally across sectors, but there exists, relatively late in the development process, a point at which they start specializing again. We discuss this finding in light of existing theories of trade and growth, which generally predict a monotonic relationship between income and diversification.

We investigate the empirical relationship between ethnicity and culture, defined as a vector of traits reflecting norms, attitudes and preferences. Using surveys of individual values in 76 countries, we find that ethnic identity is a significant predictor of cultural values, yet that within-group variation in culture trumps between-group variation. Thus, in contrast to a commonly held view, ethnic and cultural diversity are unrelated. We explore the correlates of cultural diversity and of the overlap between culture and ethnicity, finding that the level of economic development is positively associated with cultural diversity and negatively associated with the overlap between culture and ethnicity. Finally, although only a small portion of a country's overall cultural heterogeneity occurs between groups, this does not imply that cultural differences between groups are irrelevant. Indeed, we find that civil conflict becomes more likely when there is greater overlap between ethnicity and culture.