‘White gold’ guano fertilizer drove agricultural intensification in the Atacama Desert from AD 1000 av Santana-Sagredo, F, Schulting, R, Méndez-Quiros, P, Vidal-Elgueta, A, Uribe, M, Loyola, R, Maturana-Fernández, A, Díaz, FP, Latorre, C, McRostie, VB, Santoro, CM, Mandakovic, V, Harrod, C, Lee-Thorp, J