Findings in two coastal sites in Gibraltar --- Vanguard Cave and Garhams Cave --- has shown that Neanderthals enjoyed dining on sea food. the mass accumulation of remains of mollusks, fish, seals, and dolphins that litter the caves show that they routinely dined on the sea creatures for a few thousand years.
This discovery proves that our Ice Age cousins were able to formulate hunting and gathering strategies as advanced as Homo sapiens that lived at these same sites after the Neanderthal ceased to exist in history. Up until now, it was thought that H. sapiens [modern humans] competed the Neanderthal out of existence by exploiting a wider variety of foods. Neanderthals were thought to have subsisted mostly on large dangerous land mammals such as woolly rhinos.
The question of what happened to the Neanderthal grows more mysterious with this discovery. We may never know how H. sapiens became the dominate species on this planet, but it looks like our hairy Ice Age cousins were more advanced than we first thought.
For more information, please see Proceedings of the National Academy of Sciences (PNAS) September 23, 2008.