Backward-bending walrus supply

Claim (verbatim)

Backward-bending walrus supply. The backward-bending supply curve — the textbook anomaly in which workers with an income target respond to falling prices by working more, not less — is here joined to the fate of Norse Greenland. The colony's export staple was walrus ivory, and when elephant ivory re-entered European markets, Greenland ivory prices fell against it. A profit-maximizing colony should have scaled back the hunt as margins vanished. The isotope sequence already extracted from dated ivory finds records the opposite trajectory: hunters intensifying into ever riskier, more distant northern grounds. The conjecture is that this intensification tracks the price decline itself — income-target behavior, hunters working harder to hit a fixed revenue need as unit prices fell — so effort should rise as price falls throughout the decline. Profit-maximizers would have quit, not pushed north.

Prediction clause (verbatim)

For each dated sample in the existing ivory isotope sequence, take its inferred hunting-ground distance or latitude as the effort measure, and align the sequence against the relative price series of walrus versus elephant ivory. Regress effort on relative price over the period of decline. Primary clause: the effort-price relation is negative — falling relative prices accompany significantly increasing hunting distance or risk, with the negative slope significant at p < 0.05; if effort instead falls with price, or the intensification predates and is uncorrelated with the price decline, the conjecture fails. The verdict follows the primary clause.

Kill-dataset (verbatim)

the existing ivory isotope sequence against price series; profit-maximizers would have quit, not pushed north.

Novelty / leakage triage

already answered in the literature

Substantially published: Barrett and colleagues document serial depletion with hunting shifting to smaller animals from progressively more distant northern grounds, and explicitly find that exploitation INTENSIFIED in the 13th-14th centuries as ivory values fell in Europe — the harvest item's core claim including the economic reading. Chosen deliberately as a triage calibration item.

• Barrett et al. 2020, 'Ecological globalisation, serial depletion and the medieval trade of walrus rostra', Quaternary Science Reviews (Cambridge summary: 'Over-hunting walruses contributed to the collapse of Norse Greenland') — Intensification as values fell; northward shift
• 'Greenland Norse walrus exploitation deep into the Arctic', Science Advances (2024) — High-Arctic hunting grounds

Its literature citations feed the frontier as source leads (2 leads below the evidence/publication boundary, not yet reviewed).

Predictions

No prediction registered yet.