The paper, by Professor João Zilhão and colleagues, builds on his earlier research which proposed that, south of the Cantabro-Pyrenean mountain chain, Neanderthals survived for several millennia after being replaced or assimilated by anatomically modern humans everywhere else in Europe.

Although the reality of this 'Ebro Frontier' pattern has gained wide acceptance since it was first proposed by Professor Zilhão some twenty years ago, two important aspects of the model have remained the object of unresolved controversy: the exact duration of the frontier; and the causes underlying the eventual disappearance of those refugial Neanderthal populations (ecology and climate, or competition with modern human immigrants).

Professor Zilhão and colleagues now report new dating evidence for the Late Aurignacian of Portugal, an archaeological culture unquestionably associated with modern humans, that firmly constrains the age of the last Neanderthals of southern and western Iberia to no younger than some 37,000 years ago.

This new evidence therefore puts at five millennia the duration of the Iberian Neanderthal refugium, and counters speculations that Neanderthal populations could have remained in the Gibraltar area until 28,000 years ago.