The first humans with proto-Neanderthal traits are believed to have existed in Eurasia as early as 600,000–350,000 years ago with the first "true Neanderthals" appearing between 200,000 and 250,000 years ago. The exact date of their extinction had been disputed. However, in 2014, Thomas Higham of the University of Oxford performed the most comprehensive dating of Neanderthal bones and tools ever carried out, which demonstrated that Neanderthals died out in Europe between 41,000 and 39,000 years ago - this coincides with the start of a very cold period in Europe and is 5,000 years after Homo sapiens reached the continent. This was based on improved radiocarbon dating of materials from 40 sites in Western Europe.
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.
With an average cranial capacity of 1600 cm3, Neanderthal's cranial capacity is notably larger than the 1400 cm3 average for modern humans, indicating that their brain size was larger. However, owing to larger body size, Neanderthals are less encephalized. 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 28,000 years ago with a population of anatomically modern humans. According to the study, by the time that population began dispersing across Eurasia, Neanderthal genes constituted as much as 1–4% of its genome (roughly equivalent to having one Neanderthal great-great-great-grandparent). Ötzi the iceman, Europe's oldest preserved mummy, was found to possess an even higher percentage of Neanderthal ancestry. Recent findings suggest there may be even more Neanderthal genes in non-African humans than previously expected: approximately 20% of the Neanderthal gene pool was present in a broad sampling of non-African individuals, though each individual's genome was on average only 2% Neanderthal.
In December 2013, researchers reported evidence that Neanderthals practiced burial behavior and intentionally buried their dead. In addition, scientists reported, for the first time, the entire genome of a Neanderthal. The genome was extracted from the toe bone of a 130,000-year-old Neanderthal found in a Siberian cave.
The species is named after the site of its first discovery, about 12 km (7.5 mi) east of Düsseldorf, Germany, in the Feldhofer Cave in the river Düssel's Neander valley named after Joachim Neander, a 17th-century German pastor and hymnist. Neander's own name was in turn a Greek translation of the German Neumann (lit. "New man"). Thal is the older spelling of Tal (both with the same pronunciation), the German word for 'valley' (cognate with English dale).
Neanderthal 1 was known as the "Neanderthal skull" or "Neanderthal cranium" in anthropological literature, and the individual reconstructed on the basis of the skull was occasionally called "the Neanderthal man". The binomial name Homo neanderthalensis – extending the name "Neanderthal man" from the individual type specimen to the entire species – was first proposed by the Anglo-Irish geologist William King in 1864 and this had priority over the proposal put forward in 1866 by Ernst Haeckel, Homo stupidus. The practice of referring to "the Neanderthals" and "a Neanderthal" emerged in the popular literature of the 1920s.
The German pronunciation of Neanderthaler and Neandertaler is [neˈandɐˌtʰaːlɐ] in the International Phonetic Alphabet. In British English, "Neanderthal" is pronounced with the /t/ as in German but different vowels (IPA: /niːˈændərtɑːl/). In layman's American English, "Neanderthal" is pronounced with a /θ/ (the voiceless th as in thin) and /ɔ/ instead of the longer British /aː/ (IPA: /niːˈændərθɔːl/), although scientists typically use the /t/ as in German.
For some time, scientists have debated whether Neanderthals should be classified as Homo neanderthalensis or Homo sapiens neanderthalensis, the latter placing Neanderthals as a subspecies of H. sapiens. Some morphological studies support the view that H. neanderthalensis is a separate species and not a subspecies. Others, for example University of Cambridge Professor Paul Mellars, say "no evidence has been found of cultural interaction" and evidence from mitochondrial DNA studies has been interpreted as evidence Neanderthals were not a subspecies of H. sapiens.