Four sites in particular have produced archaeological and paleoanthropological evidence of occupation: Forbes' Quarry, Devil's Tower, Gorham's Cave, and Vanguard Cave. The first locality yielded the second Neanderthal fossil ever discovered, the skull of an older adult female; though found in 1848, it was not announced to science until 1865. In 1926 the second site yielded a Paleolithic (Paleolithic Period) tool assemblage and the scattered remains of a child's skull. Although the last two caves have relinquished only archaeological materials, they confirm the survival of a Middle Paleolithic technology to about 30,000 years ago, long after it had been replaced by improved toolmaking methods in northern Spain and elsewhere in Europe.

The Forbes' Quarry skull is relatively small, with a small and rounded braincase, a prominent but lightly built browridge, a very large and projecting nose (in both absolute and relative terms), swept-back cheeks, and details of the ear and neck region that align it with the Neanderthals. Its teeth are damaged, with some worn down almost to the roots and rounded from use, a pattern seen in the remains of all other older (over age 40) Neanderthals. The skull also exhibits a bony growth on the inside of the forehead, which is associated with menopause among modern humans; this may be the oldest evidence of the uniquely human pattern of menopause.

Most of the Devil's Tower skull is preserved, at least on one side, and it is clearly that of a child with a very large braincase. There are clear beginnings of a browridge (small, as befitting the individual's youth), a long and wide face, and large front teeth. The child sustained an injury to the mouth, and the teeth exhibit developmental defects, a common feature among the Neanderthals that usually indicates seasonal episodes of starvation. Neanderthal life was difficult from an early age, but these and other such finds show that many survived the hardships.