The Neanderthals (English pronunciation /niˈændərˌθɔːlz/, /niˈændərˌtɔːlz/, /niˈændərˌtɑːlz/ or /neɪˈɑːndərˌtɑːlz/) are a now-extinct species or subspecies of the genus Homo that is closely related to modern humans. They are known from fossil specimens, dating from the Pleistocene period, that have been found in Europe and parts of western and central Asia. "Neanderthal" is German for "Neander's Valley," which is the region of Germany where the species was first discovered. (The species name is also sometimes spelled Neandertal, because that is the modern German spelling of the valley's name.)
Neanderthals are classified either as a subspecies of Homo sapiens (Homo sapiens neanderthalensis) or as a separate species of the same genus (Homo neanderthalensis). The first humans with proto-Neanderthal traits are believed to have existed in Europe as early as 600,000–350,000 years ago. Specimens with proto-Neanderthal traits are occasionally grouped instead with another phenetic species, such as Homo heidelbergensis, or a migrant form, Homo rhodesiensis.
Neanderthals went extinct no earlier than about 33,000 years ago, and probably more recently than that. No Neanderthal fossils more recent than 30,000 years ago have been found; among the most recent are those found in the Vindija Cave in Croatia, which are between 33,000 and 32,000 years old. However, evidence at a site in Gibraltar suggestive of fire use by Neanderthals raises the possibility that they might have survived there until as recently as 24,000 years ago. Cro-Magnon (early-modern-human) skeletal remains showing certain "Neanderthal traits" have been found in Lagar Velho (Portugal) and dated to 24,500 years ago, suggesting that there was an extensive admixture of the Cro-Magnon and Neanderthal populations in that region.
Several cultural assemblages have been linked to the Neanderthals in Europe. The earliest, the Mousterian stone tool culture, dates to about 300,000 years ago. Late Mousterian artifacts were found in Gorham's Cave on the south-facing coast of Gibraltar. Other tool cultures associated with the Neanderthals include the Châtelperronian, the Aurignacian, and the Gravettian; their tool assemblages appear to have developed gradually within their populations, rather than being introduced by new population groups arriving in the region.
Neanderthal cranial capacity is thought to have been as large as that of modern humans, perhaps larger, indicating that their brain size may have been comparable, or larger, as well. In 2008, a group of scientists created a study using three-dimensional computer-assisted reconstructions of Neanderthal infants based on fossils found in Russia and Syria. The study showed Neanderthal and modern human brains were the same size at birth, but by adulthood, the Neanderthal brain was larger than the modern human brain. They were much stronger than modern humans, having particularly strong arms and hands. Males stood 164–168 cm (65–66 in) and females about 152–156 cm (60–61 in) tall.
Genetic evidence published in 2010 suggests that Neanderthals contributed to the DNA of anatomically modern humans, probably through interbreeding between 80,000 and 50,000 years ago with the population of anatomically modern humans who had recently migrated from Africa. According to the study, by the time that population began dispersing across Eurasia, Neanderthals genes constituted as much as 1–4% of its genome.