GMAT Verbal Reasoning

For much of the twentieth century, economists treated rapid population growth as a drag on development, reasoning that more mouths to feed would dilute a society’s capital and depress incomes. A later shift in thinking drew attention not to the size of a population but to its age structure. As mortality falls and, some years afterward, fertility declines, a country passes through a phase in which the working-age share of the population is unusually large relative to the dependent young and old. Several economists credited this so-called demographic dividend with a substantial part of the rapid growth recorded by a number of East Asian economies in the late twentieth century.

The proposed mechanism is straightforward. With fewer children to support, households can save a larger share of their income and invest more in the schooling of each child; meanwhile, the swelling of the working-age cohort raises output per head almost arithmetically, simply because a greater fraction of the population is in a position to produce. On this view, a favorable age structure functions as an engine of growth.

Yet the dividend is not collected automatically. A bulge of working-age adults raises output only if the economy generates enough jobs to employ them; where the demand for labor is weak, the same age structure can yield idleness and unrest rather than prosperity. Cross-country studies that attributed East Asia’s performance to age structure frequently omitted the policies—widening access to schooling, openness to trade, the secure enforcement of contracts—that allowed the potential labor force to be productively absorbed. Once those policies are taken into account, the independent contribution of age structure looks more modest.

It is therefore more accurate to describe the demographic dividend as a window of opportunity than as a cause. Two countries with identical age structures can diverge sharply, depending on whether the complementary investments are made before the window closes—for the working-age share eventually falls, and the burden of dependency shifts from the young to the elderly.

Beneath many forests, the roots of trees are joined by threads of fungus that trade soil nutrients for the sugars the trees produce by photosynthesis. Experiments using carbon labeled with a detectable isotope have shown that carbon can travel from one tree, by way of these shared fungal connections, to a neighboring tree. Popular accounts seized on such findings to describe a cooperative “wood wide web,” a network through which mature trees deliberately feed their seedlings and even warn their neighbors of approaching pests.

The evidence for transfer is real, but it is narrower than the popular story implies. The labeled carbon that reaches a second plant is typically a small fraction of what the donor fixed, and much of it may remain within the fungus itself rather than passing into the recipient tree. To show that a molecule moves between two plants is not yet to show that the receiving plant gains any meaningful advantage.

Skeptics press a further point: the fungus is not a passive pipe arranged for the convenience of the trees. Mycorrhizal fungi are organisms in their own right, shaped by natural selection, and where carbon happens to move in a direction that favors a fungus’s own spread, to credit the flow to tree “cooperation” is to mistake who benefits. Field studies that control for the identity of the fungus connecting two plants, instead of assuming a unified network, tend to find effects weaker and less consistent than the laboratory demonstrations had suggested.

None of this denies that mycorrhizal associations matter to forests; plainly they do. The dispute is one of interpretation—whether the documented transfers reveal an adaptive system of support among trees, or simply the ordinary trading and competition of distinct organisms whose interests align only sometimes.

For centuries, readers assumed that the Iliad and the Odyssey were composed in writing by a single poet of extraordinary genius. In the early twentieth century, the comparative study of living oral traditions suggested another possibility. Observing unlettered singers in the Balkans who could perform narrative poems of enormous length, scholars argued that the Homeric epics bore the marks of composition in performance: recurring fixed phrases, or “formulae,” shaped to fit the meter, and repeated type-scenes that a singer could deploy to build verse rapidly without committing a fixed text to memory.

This oral-formulaic theory accounted elegantly for features that had long puzzled critics, among them the poems’ frequent repetitions and their occasional inconsistencies. If the epics were assembled in performance out of inherited components, small contradictions were only to be expected and called for no elaborate explanation.

The theory’s very success, however, provoked a reaction. Some scholars countered that the presence of formulae does not preclude sophisticated design; a tradition can hand a poet ready-made building blocks that a gifted composer then arranges with deliberate artistry. The large-scale architecture of the Odyssey, with its careful interlacing of separate plot lines, struck several critics as hard to credit to improvisation alone. Others observed that the passage from oral performance to written text—by whatever hand it was accomplished—may itself have been the moment at which the poems we possess took shape.

The debate has accordingly moved away from a flat opposition between “oral” and “literate” toward a subtler question: how a traditional medium and an individual shaping intelligence combined to produce the texts that survive. The evidence that remains—the poems themselves, read across many centuries of changing expectation—does not settle that question cleanly.