The caverns and passages were formed in the early Pleistocene period by water action, and have been occupied by one of at least eight separate, discontinuous native populations to have inhabited the British Isles. The other key paleolithic sites in the UK are Happisburgh, Pakefield, Boxgrove, Swanscombe, Pontnewydd, Paviland, Creswell Crags and Gough's Cave.
A prehistoric maxilla (upper jawbone) fragment was discovered in the cavern during a 1927 excavation by the Torquay Natural History Society, and named Kents Cavern 4. The specimen is on display at the Torquay Museum.
In 1989 the fragment was radiocarbon dated to 36,400?34,700 years BP, but a 2011 study that dated fossils from neighbouring strata produced an estimate of 44,200?41,500 years BP. The same study analysed the dental structure of the fragment and determined it to be Homo sapiens rather than Homo neanderthalensis, which would have made it the earliest anatomically modern human fossil yet discovered in northwestern Europe. In a response to this paper in 2012 the authors Mark White and Paul Pettitt wrote "We urge caution over using a small selected sample of fauna from an old and poorly executed excavation in Kent?s Cavern to provide a radiocarbon stratigraphy and age for a human fossil that cannot be dated directly, and we suggest that the recent dating should be rejected.