Neanderthal cavemen supped on shellfish on the Costa del Sol 150,000 years ago, punching a hole in the theory that modern humans alone ate brain-boosting seafood so long ago, a new study shows. The discovery in a cave near Torremolinos in southern Spain was about 100,000 years older than the previous earliest evidence of Neanderthals consuming seafood, scientists said. Researchers unearthed the evidence when examining stone tools and the remains of shells in the Bajondillo Cave, they said in a study published online in the Public Library of Science. There, they discovered many charred shellfish -- mostly mussel shells -- left by Neanderthals. They were able to date the shells by radiocarbon testing to about 150,000 years ago. That is "almost contemporaneous" to the earliest evidence of modern humans eating shellfish at Pinnacle Point in South Africa 164,000 years ago, said the study led by the University of Seville's Miguel Cortes Sanchez. "This discovery makes the Bajondillo Cave the oldest record of this activity among Neanderthals, as the earliest evidence until now did not go back further than 50,000 years," said Francisco Jimenez Espejo, researcher at the Spanish National Research Council (CSIC), which was part of the study. "Many researchers argue that eating shellfish is one of the behaviours that define modern humans and to a certain extent an adaptive advantage that allowed homo sapiens to expand," Espejo said. "But this investigation shows that at the same time as homo sapiens in southern Africa, homo neanderthalensis in the southern Iberian peninsula used the same resources."