The peninsula stood on the edge of a fertile coastal plain, now submerged, that supported a wide variety of animals and plants which the Neanderthals exploited to provide a highly varied diet.
They gave a report on it to the British Association for the Advancement of Science in 1864 and proposed that the species be called Homo calpicus after Mons Calpe, the ancient name for Gibraltar.
[6] Busk described it as "characteristic of a race extending from the Rhine to the Pillars of Hercules", highlighting its importance as confirmation that the Neanderthal 1 specimen was genuinely a member of a distinct species and not simply a deformed Homo sapiens.
[7] The skull was the first Neanderthal adult cranium to be discovered and, although small, is nearly complete;[6] it is thought to have belonged to a woman due to its gracile features.
In 1926, a second Neanderthal skull was found by Dorothy Garrod at a rock shelter named Devil's Tower, very close to Forbes' Quarry.
[9] The limestone massif of the Rock of Gibraltar is riddled with caves – its ancient name, Calpe, means "hollow"[10] – and it was here that archaeologists focused their efforts to find sites of Neanderthal occupation.
[14] Consisting of a series of intersecting lines, the engraving is located about 100 metres (330 ft) inside the cave on a ledge that is thought to have been used by Neanderthals as a sleeping place.
[14] The engraving was clearly made deliberately, rather than being an accidental by-product of another process such as cutting meat or fur, and would have taken a significant amount of effort to carve into the dolomite rock of the cave.
The iconic ice age mammals of northern Europe – woolly rhinos, mammoths, bison, reindeer, muskox and cave bears – never made it as far south as Gibraltar, which enjoyed a temperate and stable year-round climate due to its southerly latitude, distance from the coastal mountains and position on the Mediterranean shore.
They probably did not stay there year-round but lived in widely dispersed groups that roamed across the open savannah and coastal wetlands of southern Iberia, seeking seasonal supplies of food.
Gibraltar's southerly latitude would have meant a fairly constant pattern of activity throughout the year due to the long days and mild climate, in contrast to the more abruptly seasonal lifestyle of the Neanderthals who lived further north.
More dangerous animals like wild boar, aurochs and rhino appear to have been avoided – understandably so, given that the Neanderthals are thought to have relied on using thrusting spears in close-quarter ambushes.
The Neanderthals exploited Gibraltar's location as one of Europe's focal points for migratory birds, by catching and eating them in large quantities.
[23] They certainly ate shellfish in large quantities; many mussel shells have been found in the caves, indicating that the Neanderthals harvested them from the seashore and brought them back over a considerable distance, perhaps carrying them in bags made from animal skins.
[12] They did not disappear during the Last Glacial Maximum during the time of the H2 Heinrich event, when ocean circulations were disrupted by very rapid climate fluctuations which coincided with the disintegration of coastal ice sheets.
Their population had probably been shrinking for millennia and the abrupt climate change may have stressed them beyond recovery, leaving them vulnerable to the effects of inbreeding and outbreaks of disease.