Neanderthal

"Neandertal" redirects here. For the location in Germany, see Neandertal (valley).

"Neanderthal Man" redirects here. For the 1970 single by English pop rock band Hotlegs, see Neanderthal Man (song).

Neanderthal Temporal range: Middle–Late Pleistocene
An approximate reconstruction of a Neanderthal skeleton. The central rib cage, including the sternum, and parts of the pelvis are from modern humans.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Family:	Hominidae
Subfamily:	Homininae
Tribe:	Hominini
Genus:	Homo
Species:	†H. neanderthalensis
Binomial name
†Homo neanderthalensis King, 1864
Known Neanderthal range in Europe (blue), Southwest Asia (orange), Uzbekistan (green), and the Altai Mountains (violet).
Synonyms
Homo H. stupidus Haeckel, 1895 H. europaeus primigenius Wilser, 1898 H. primigenius Schwalbe, 1906 H. antiquus Adloff, 1908 H. transprimigenius mousteriensis Farrer, 1908 H. mousteriensis hauseri Klaatsch 1909 H. priscus Krause, 1909 H. chapellensis von Buttel-Reepen, 1911 H. calpicus Keith, 1911 H. acheulensis moustieri Wiegers, 1915 H. lemousteriensis Wiegers, 1915 H. naulettensis Baudouin, 1916 H. sapiens neanderthalensis Kleinshmidt, 1922 H. heringsdorfensis Werthe, 1928 H. galilensis Joleaud, 1931 H. primigenius galilaeensis Sklerj, 1937 H. kiikobiensis Bontsch-Osmolovskii, 1940 H. sapiens krapinensis Campbell, 1962 H. erectus mapaensis Kurth, 1965 Palaeoanthropus P. neanderthalensis McCown and Keith, 1939 P. heidelbergensis McCown and Keith, 1939 P. ehringsdorfensis Paterson, 1940 P. krapinensis Sergi, 1911 P. palestinensis McCown and Keith, 1939 P. europaeus Sergi, 1910 Protanthropus P. atavus Haeckel, 1895 P. tabunensis Bonarelli, 1944 Acanthropus A. neanderthalensis Arldt, 1915 A. primigenius Abel, 1920 A. neanderthalensis Dawkins, 1926

Neanderthals (/niˈændərtɑːl, neɪ-, -θɔːl/; German: Neandertaler [neˈ(ʔ)andɐtaːlɐ]; Homo neanderthalensis or Homo sapiens neanderthalensis), alternatively spelt as "Neandertals", are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago (kya). They went extinct probably by competition or extermination by immigrating humans, great climatic change, disease, or some combination.

It is unclear when Neanderthals split from humans, with DNA studies ranging from 182 kya to before 800 kya, and the time of divergence from the ancestral Homo heidelbergensis is also vague. The oldest potential Neanderthal bones are dated to 430 kya, but the classification is uncertain. They are known from numerous fossils, especially following 130 kya. The type specimen, Neanderthal 1, was found in 1856 in the German Neander Valley. After much debate over its validity, Neanderthals were depicted as being primitive, stupid, and brutish, for much of the early 20th century. Though their image in the scientific community has markedly changed since, the unevolved caveman archetype remains aloof in popular culture.

Compared to modern humans, Neanderthals were stockier with somewhat shorter limbs, and bigger chest and nose. These are often explained as adaptations to conserve heat in a cold climate, but are more likely adaptations for sprinting in the warmer, forested landscape they often inhabited, and products of genetic drift. The braincases of Neanderthal men and women averaged about 1,600 cm³ (98 cu in) and 1,300 cm³ (79 cu in) respectively, within the range of the values for modern humans. Average Neanderthal men stood around 165 cm (5.5 ft) and women 153 cm (5 ft) tall, similar to contemporary humans.

Neanderthal technology is thought to have been somewhat sophisticated, and include the Mousterian stone tool industry, the ability to create fire and build cave hearths, making the adhesive birch bark tar, crafting simple clothes similar to blankets and ponchos, seafaring through the Mediterranean, making use of medicinal plants, and using various cooking techniques (such as roasting and smoking). Though they were likely apex predators, they still competed with cave bears, cave lions, cave hyaenas, and wolves.^:120–143 Several examples of Upper Paleolithic art have been controversially attributed to Neanderthals–most famously Spanish cave paintings contentiously dated to before 65 kya–and some claims of religious beliefs have been made. They were capable of speech, though it is unclear how complex their language would have been.

They likely lived in small groups, lacked sexual division of labour, and put children to work at a very young age. Neanderthals lived in a high-stress environment with high trauma rates, and about 80% died before the age of 40. They had a low population, leading to the accumulation of harmful genes and inbreeding. Interbreeding between Neanderthals and anatomically modern humans was concluded in the 2010 Neanderthal genome project's draft report, possibly occurring 316–219 kya, and more likely occurring 100 kya and again after 65 kya. Around 1–4% of all non-Subsaharan African genomes (Eurasians, Oceanians, Native Americans, and North Africans) derive from Neanderthals, and about 20% of the Neanderthal genome survives today, but many of the inherited genes may have been detrimental and selected out.

Taxonomy

See also: Human taxonomy

Etymology

What remains of Kleine Feldhofer Grotte where Neanderthal 1 was discovered

Neanderthals are named after the site they were first identified in, the Neander Valley, at the time in the Rhine Province of the Kingdom of Prussia (now in North Rhine-Westphalia, Germany). The valley itself was named for Joachim Neander, Neander being the Hellenized form of the surname Neumann ("new man").

Neanderthal 1, the type specimen, was known as the "Neanderthal cranium" or "Neanderthal skull" 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 group, and formally recognizing it as distinct from humans—was first proposed by Irish geologist William King in a paper read to the 33rd British Science Association in 1863. However, in 1864, he recommended the genus name also be distinct from humans as he compared the Neanderthal braincase to that of a chimpanzee and argued it was "incapable of moral and theositic conceptions".

Ernst Haeckel's Primate family tree showing H. stupidus (Neanderthal) as the ancestor to H. sapiens

Since the historical spelling -th- in German represents the phoneme /t/, not the usual pronunciation of th with the fricative /θ/, standard British pronunciation of "Neanderthal" is with /t/ (IPA: /niːˈændərtɑːl/). However, in English, "Neanderthal" is also pronounced with the usual th sound (as /niːˈændərθɔːl/).

The German spelling of "Thal" ("valley") was current until 1901; it is now spelt "Tal". The spelling "Neandertal" is occasionally seen in English, even in scientific publications. Since "Neanderthal" and "Neandertal" are common names, there is no authoritative prescription on its spelling, unlike the spelling of the binominal name, H. neanderthalensis, which is predicated by King, 1864. The common name in German is invariably "Neandertaler" (lit. "of the valley of Neander"), not "Neandertal", but the spelling of the name of the Neander Valley itself ("Neandertal" vs. "Neanderthal") has been affected by the species name, the names of the Neanderthal Museum and of Neanderthal station persisting with pre-20th-century spelling.

Research history

See also: Human taxonomy

Skullcap of Neanderthal 1, the type specimen

The first Neanderthal remains ever discovered–Engis 2–was in 1829 by Dutch naturalist Philippe-Charles Schmerling in the Schmerling Caves, but he thought it was an ancient human skull. In 1848, Gibraltar 1 from Forbes' Quarry was presented to the Gibraltar Scientific Society by their Secretary Lieutenant Edmund Henry Réné Flint, but was also thought to be a human skull. In 1856, local schoolteacher Johann Carl Fuhlrott recognized bones from Feldhofer Cave in Neander Valley–Neanderthal 1 (the holotype specimen)–as distinct from humans, and gave it to German anthropologist Hermann Schaaffhausen to study in 1857. It comprised the cranium, thigh bones, right arm, left humerus and ulna, left ilium (hip bone), part of the right shoulder blade, and pieces of the ribs. Following Charles Darwin's On the Origin of Species, Fuhlrott and Schaaffhausen argued the bones represented an ancient human form; Schaaffhausen, a social darwinist, believed that humans linearly progressed from savage to civilised, and so concluded that Neanderthals were barbarous cave-dwellers. However, they met opposition namely from the prolific pathologist Rudolf Virchow who argued against defining new species based on only a single find. In 1872, Virchow erroneously interpreted Neanderthal characteristics as evidence of senility, disease, and malformation instead of archaicness, which stalled Neanderthal research until the end of the century.

From The Grisly Folk by H. G. Wells

By the early 20th century, numerous other Neanderthal discoveries were made, establishing Neanderthal as a legitimate species, the most influential specimen La Chapelle-aux-Saints 1. French palaeontologist Marcellin Boule made several publications, among the first to establish palaeontology as a science, detailing the specimen, but reconstructed it as ape-like and only remotely related to humans, and fueled the popular image of Neanderthals as barbarous, slouching, club-wielding primitives; this image was reproduced for several decades and popularised in science fiction works, such as the 1911 The Quest for Fire by J.-H. Rosny aîné and the 1927 The Grisly Folk by H. G. Wells where they are depicted as monsters. In 1911, Scottish anthropologist Arthur Keith reconstructed La Chapelle-aux-Saints 1 as an immediate precursor to humans, sitting next to a fire, producing tools, wearing a necklace, and having a more humanlike posture, but this failed to garner much scientific rapport, and Keith later abandoned his thesis in 1915.

By the middle of the century, based on several recent findings of other human ancestors (such as Homo erectus), the scientific community began to rework its understanding of Neanderthals. Ideas such as Neanderthal behaviour, intelligence, and culture were being discussed, and a more humanlike image of them emerged. In 1939, American anthropologist Carlton Coon reconstructed a Neanderthal in a modern business suit and hat to emphasize that they would be, more or less, indistinguishable had they survived into the present. William Golding's 1955 novel The Inheritors depicts Neanderthals as much more emotional and civilised. However, Boule's image continued to influence works until the 1960s. In modern day, Neanderthal reconstructions are often very humanlike.

Hybridization between Neanderthals and early humans had been suggested early on, such as by English anthropologist Thomas Huxley in 1890, ethnographer Hans Peder Steensby in 1907, and Coon in 1962. In the early 2000s, several researchers argued in favour of admixture based on supposed hybrid specimens such as Lagar Velho 1 and Muierii 1. Neanderthal admixture was found to be present in modern populations in 2010 with the mapping of the first Neanderthal genome sequence.

Classification

Hominina Chimpanzee Humans Denisovan from Denisova Cave Denisovan from Baishiya Karst Cave Neanderthal from Denisova Cave Neanderthal from Sidrón Cave Neanderthal from Vindija Cave

Phylogeny of Hominina based on comparison of ancient proteomes and genomes with those of modern species.

Neanderthals are hominids in the genus Homo, and generally classified as a distinct species, H. neanderthalensis, though sometimes as a subspecies of human as H. sapiens neanderthalensis. This would necessitate the classification of modern humans as H. s. sapiens.

A large part of the controversy stems from the vagueness of the term "species", as it is generally used to distinguish two genetically isolated populations, but admixture between modern humans and Neanderthals is known to have occurred. However, the absence of Neanderthal-derived patrilineal Y-chromosome and matrilineal mitochondrial DNA (mtDNA) in modern humans, along with the underrepresentation of Neanderthal X chromosome DNA, could imply reduced fertility or frequent sterility of some hybrid crosses, representing a partial biological reproductive barrier between the groups.

In 2014, geneticist Svante Pääbo described such "taxonomic wars" as unresolveable, "since there is no definition of species perfectly describing the case."

Neanderthals were more closely related to Denisovans than to humans based on nuclear DNA. However modern humans and Neanderthals share a more recent common mitochondrial lineage than that of Denisovans. This likely resulted from an interbreeding event subsequent to the Neanderthal/Denisovan split which introduced another mtDNA line. This involved either introgression coming from an unknown archaic human into Denisovans, or the mtDNA of Neanderthals being replaced by that of a modern human lineage deriving from an early H. sapiens wave from Africa. Older specimens show distinct genetic populations of Neanderthals in different regions, but DNA samples from Mezmaiskaya Cave in the Caucasus and Denisova Cave in the Siberian Altai Mountains show apparent replacement of their local populations by a different population also found in Western European sites.

Evolution

Stage 1: early pre-Neanderthal, possibly H. erectus, (Tautavel Man, 450 kya)

Stage 2: archaic Neanderthal, possibly H. heidelbergensis (Miguelón, 430 kya)

Stage 3: early Neanderthal (Saccopastore I, 130 kya)

Stage 4: classic European Neanderthal (La Chapelle-aux-Saints 1, 50 kya)

The accretion model

Further information: Human evolution § Neanderthal and Denisovan, and Neanderthal genetics

It is largely thought that H. heidelbergensis was the last common ancestor of Neanderthals, Denisovans, and modern humans after populations became isolated in Europe, Asia, and Africa respectively. The taxonomic distinction between H. heidelbergensis and Neanderthals is mostly due to a fossil gap in Europe between 300 and 243 thousand years ago (kya) during Marine isotope stage 8. "Neanderthals", by conventions, are fossils which date to after this gap. However, 430,000 year (ka) old bones at Sima de los Huesos could represent early Neanderthals or a closely related group, and the 400 ky old Aroeira 3 could represent a transitional phase. Basal and derived morphs could have lived concurrently. The quality of the fossil record greatly increases from 130,000 years ago (kya) onwards, and make up the bulk of known Neanderthal skeletons. Dental remains from the Italian Visogliano and Fontana Ranuccio sites indicate that Neanderthal dental features had evolved by around 450–430 kya during the Middle Pleistocene.

There are two main hypotheses regarding the evolution of Neanderthals following the Neanderthal/human split: two-step and accretion. The former argues a single major environmental event–such as the Saale glaciation–caused European H. heidelbergensis to rapidly increase body size, robustness, and an enlengthenment of the head, which then led to other changes in skull anatomy. However, Neanderthal anatomy was most likely not driven by adapting to cold weather. The latter holds that Neanderthals slowly evolved over time from the ancestral H. heidelbergensis, divided into 4 stages: early-pre-Neanderthals (MIS 12), pre-Neanderthals (MIS 11–9), early Neanderthals (MIS 7–5), and classic Neanderthals (MIS 4–3).

Numerous dates for the Neanderthal/human split exist. The date of around 250 kya cites the Florisbad Skull ("H. helmei") as being the last common ancestor (LCA), and the split is associated with the Levallois technique of making stone tools. The date of about 400 kya uses H. heidelbergensis as the LCA. 600 kya says that "H. rhodesiensis" was the LCA, which split off into a human lineage and a Neanderthal/H. heidelbergensis lineage. 800 kya has H. antecessor as the LCA; however, different variations of this model would push the date back to 1 million years ago. DNA studies have yielded various results on divergence time, such as 592–182 kya, 553–321 kya, 654–475 kya, 690–550 kya, 765–550 kya, 800–520 kya, before 800 kya, and so forth.

Neanderthals and Denisovans are more closely related to each other than they are to humans, meaning the Neanderthal/Denisovan split occurred after their split with humans. Using a mutation rate of 1x10^-9 or 0.5x10^-9 per base pair (bp) per year, the Neanderthal/Denisovan split occurred around either 236–190 kya or 473–381 kya respectively. Using 1.1x10^-8 per generation with a new generation every 29 years, the time is 744 kya. Using 5x10^-10 nucleotide site per year, it is 644 kya. Using the latter dates, the split had likely already occurred by the time hominins spread out across Europe, and unique Neanderthal features had begun evolving by 600–500 kya.

Demographics

Further information: Neanderthals in Southwest Asia, Neanderthals in Gibraltar, and List of Neanderthal sites

Range

One of the most southernmost Neanderthal remains from Tabun Cave, Israel (120–50 kya) at the Israel Museum

Early Neanderthals, living before the Eemian interglacial (130 kya), are poorly known and come mostly from European sites. From 130 kya onwards, the quality of the fossil record increases dramatically, recorded from Western, Central, Eastern, and Mediterranean Europe, as well as Southwest, Central, and Northern Asia up to the Altai Mountains in southern Siberia.

The southernmost find was recorded at Shuqba Cave, Levant, and the easternmost at Denisova Cave, Siberia 85°E. The southeast Chinese Maba Man, a skull, shares several physical attributes with Neanderthals, though these may be the result of convergent evolution rather than Neanderthals extending their range to the Pacific Ocean. The limit of their northern bound appears to have been 53°N (Bontnewydd, Wales), although it is difficult to assess because glacial advances destroy most human remains. Middle Palaeolithic artefacts have been found up to 60°N on the Russian plains, but these are more likely attributed to humans. A 2017 study claimed the presence of Homo at the 130 ka Californian Cerutti Mastodon site, but this is highly unlikely.

It is unknown how the rapidly fluctuation climate of the last glacial period (Dansgaard–Oeschger events) impacted Neanderthals, as warming periods would produce more favorable temperatures, but encourage forest growth and deter megafauna; whereas frigid periods would produce the opposite. Populations may have peaked in cold but not extreme intervals, such as marine isotope stages 8 and 6. It is possible their range expanded and contracted as the ice retreated and grew respectively to avoid permafrost areas, residing in certain refuge zones. However, Neanderthals may have preferred a forested landscape.

Distribution of Neanderthals and locations of main excavation sites

Population

Like modern humans, Neanderthals probably descended from a very small population with an effective population–the number of individuals who can bear children–of 3,000 to 12,000 approximately. However, Neanderthals maintained this very low population, living in small, isolated, inbred groups. Various studies, using mtDNA analysis, yield varying effective populations, such as about 1,000 to 5,000; 5,000 to 9,000 remaining constant; or 3,000 to 25,000 steadily increasing until 50,000 BCE before declining until extinction. However, all agree on low population, which may have been up to 10 times smaller than contemporary human populations in Western Europe. Estimates giving a total population in the tens of thousands are contested. A consistently low population may be explained in the context of the "Boserupian Trap": a population's carrying capacity is limited by the amount of food it can obtain, which in turn is limited by its technology. Innovation increases with population, but if the population is too low, innovation will not occur very rapidly and the population will maintain its low population. This is consistent with the apparent 150 kya stagnation in Neanderthal technology.

This low population caused a low genetic diversity, inbreeding, and reduced the population's ability to filter out harmful mutations. However, it is unknown how this affected a single Neanderthal's genetic burden and, thus, if this caused a higher rate of birth defects than in humans. It is known, however, that the Neanderthals of Sidrón Cave displayed several birth defects.

Based on tropical human hunter-gatherer societies, adult Neanderthals possibly lived on average 25–40 years. In a sample of 206 Neanderthals, based on the abundance of young and mature adults in comparison to other age demographics, about 80% of them above the age of 20 died before reaching 40. This high mortality rate was probably due to their high-stress environment. However, it has also been estimated that the age pyramids for Neanderthals and Upper Paleolithic humans were the same. Infant mortality was very high, about 43% in northern Eurasia.

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Some locations of Neanderthal finds (note Denisova, Bisitun, Obi-Rakhmat, Anghilak, and Teshik-Tash Caves are cut off)

Anatomy

Main article: Neanderthal anatomy

Build

Comparisons of a human (left) and a Neanderthal (right) skull at the Cleveland Museum of Natural History

Neanderthal skull features

Neanderthals had a more robust and stockier build than humans, though still maintained an upright posture; wider and barrel-shaped rib cage; wider pelvis; and proportionally shorter forearms and forelegs.

Based on 45 Neanderthals long bones from 14 men and 7 women, the average height was 164 to 168 cm (5.4 to 5.5 ft) for men and 152 to 156 cm (5 ft) for women. For comparison, the average height of 16 Upper Paleolithic and Mesolithic humans was 168.1 cm (5.5 ft) for men and 152.5 cm (5 ft) for women. For Neanderthal weight, samples of 26 specimens found an average of 77.6 kg (171 lb) for men and 66.4 kg (146 lb) for women. Using 76 kg (168 lb), the body mass index for Neanderthal men was calculated to be 2.69–2.82, which in humans correlates to obesity. This indicates a very stocky build.

Body proportions are usually cited as being "hyperarctic" as adaptations to the cold, as they are similar to those of human populations which developed in cold climates–the Neanderthal build is most similar to Eskimos–and shorter limbs equates to higher retention of body heat, but Neanderthals from more temperate climates–such as Iberia–still retain the "hyperarctic" physique. Further, the increasing evidence that Neanderthals preferred warmer wooded areas instead of open mammoth steppe and cold climate suggests to the contrary, and DNA analysis indicates a higher proportion of fast-twitch muscle fibers in the Neanderthals than humans. It is possible their body proportions and greater muscle mass were adaptations to sprinting as opposed to the endurance-oriented human physique, as shorter limbs reduce moment arm at the limbs, which allows for greater rotational force at the wrists and ankles without extra exertion of the rotating muscles at the elbows and knees by increasing the speed at which the muscles contract, allowing for faster acceleration.

Several adaptations in the leg joints could possibly suggest habitual squatting, which, if the case, was likely done while gathering food.

Face

Le Moustier Neanderthal facial reconstitution at the Neues Museum, Berlin

Neanderthals had a reduced chin, sloping forehead, and large nose which also started somewhat higher on the face than in modern humans. The Neanderthal skull is typically more elongated and less globular than that of humans, and features an occipital bun, or "chignon", a protrusion on the back of the skull, though it is within the range of variation for humans who have it. It is caused by the cranial base and temporal bones being placed higher and more towards the front of the skull, and a flatter skullcap. They likely also had larger eyes to adapt to the low-light environment.

The large Neanderthal nose and paranasal sinuses were once thought to warm air as it entered the lungs and retain moisture ("nasal radiator hypothesis"), but the bone structure does not indicate any adaptations to cold climate, and sinuses are generally reduced in cold-adapted creatures. More likely, the large nose was caused by genetic drift; also, the sinuses are not grossly large, and are comparable in size to those of humans.

Neanderthals featured a protrusion of the jaw (prognathism), which was once cited as a response to a large bite force evidenced by heavy wearing of Neanderthal front teeth (the "anterior dental loading hypothesis"), but similar wearing trends are seen in contemporary humans. It could also have evolved to fit larger teeth in the jaw which better resists wear and abrasion, and the increased wear on the front teeth compared to the back teeth probably stem from repetitive use. Neanderthal dental wear patterns are most similar to those of modern Inuit. The bite force of Neanderthals and humans is now thought to be about the same, about 285 N (64 lbf) and 255 N (57 lbf) in human men and women, respectively.

Brain

The Neanderthal braincase averages 1,600 cm³ (98 in³) for men and 1,300 cm³ (79 in³) for women, within the possible range of modern humans, which is, on average, 1,270 cm³ (78 in³) for men and 1,130 cm³ (69 in³) for women. The largest Neanderthal brain, Amud 1, was calculated to be 1,736 cm³ (105.9 in³), one of the largest ever recorded in hominids. However, both Neanderthal and human infants measure about 400 cm³ (24 in³), and either Neanderthal brain development sped up or human development slowed down from the last common ancestor.

In Neanderthals, the occipital lobe–operating vision–was much larger than in modern humans, and, similarly, they had larger eyes, probably as an adaptation to lower light conditions in Europe. More brain tissue was devoted to bodily maintenance and control, and, consequently, the cognitive areas of the brain were proportionally smaller than in humans, including the cerebellum–operating muscle memory, and possibly language, attention, working memory, social abilities, and thought–the parietal lobes–visuospatial function and episodic memory–the temporal lobes–language comprehension and associations with emotions–the orbitofrontal cortex–decision making–and the olfactory bulb–sense of smell. A 2011 study looking at the brain asymmetry of 20 Neanderthals to predict handedness found 85% to be right-hand dominant and the remaining 15% left-handed, whereas humans are 52% right-dominant, 12% left-dominant, and 36% ambidextrous.

Hair and skin colour

File:Kermanshah Pal Museum-Neanderthal.jpg

Reconstruction of a Croatian Neanderthal at the Zagros Paleolithic Museum

The lack of sunlight most likely led to the proliferation of lighter skin in Neanderthals. Genetically, BNC2 was present in Neanderthals, which is associated with light skin colour, however, a second variation of BNC2 was also present, which is associated with darker skin colour in the UK Biobank. It is likely Neanderthal skin colour varied from region to region. The DNA of three Croatian Neanderthals shows they had darker hair, skin, and eye colour than modern Europeans, though modern Europeans did not evolve light skin and hair until the Holocene.

The DNA of a Neanderthal from Monti Lessini, Valpolicella, Italy, showed depressed activity of the MC1R gene, which is associated with red or blond hair. However, like in humans, red was probably not a very common hair color.

Metabolism

The Neanderthal physical activity level (PAL) was assumed to be a very high 650 counts per minute per day (CPM/d), in comparison to 200 CPM/d in modern Siberian hunter-gatherers. Average body fat percentage (BFP) was estimated to be 25%, though it may have been 13% in men and 20% in women in more temperate areas. Using these measurements and average height and weight, the daily total energy expenditure (TEE)–the amount of calories consumed in one day–was estimated to be 3,454–4,019 and 3,828–4,483 kcal for men with high and low BFPs respectively, and 3,115–3,538 and 3,258–3,710 kcal for women. However, if the PAL was reduced to that of modern Siberian hunter-gatherers, the TEE becomes 2,959–3,524 and 3,333–3,988 kcal for men, and 2,620–3,043 and 2,764–3,215 kcal for women. This is comparable with the upper end of energetic demands of modern hunter gatherers, and the latter estimates are most similar to the Siberian Yakuts, which contradicts earlier estimates of vastly higher energetic demands in Neanderthals than humans. Further, some Neanderthal populations are thought to have had a predominantly low-calorie plant diet, which suggests the minimum daily caloric intake was also low.

File:Reconstruction of Neanderthal woman.jpg

Reconstruction of a Neanderthal woman.

Maximum lifespan, and the timing of adulthood, menopause, and gestation were most likely very similar to modern humans. However, it has been hypothesized that Neanderthals matured faster than modern humans based on the growth rates of teeth and tooth enamel, though this is not backed by age biomarkers.

Genetically, Neanderthal-derived alleles near ASB1 and EXOC6 are associated with being an evening person, narcolepsy, and day-time napping. In a survey, people who had archaic haplotypes near CDH6 more frequently reported feeling unenthusiasm and disinterest. These are consistent with the idea that sunlight affects circadian rhythm and mood.

Pathology

Neanderthals suffered a high rate of traumatic injury, with an estimated 79–94% of specimens showing evidence of healed major trauma, of which 37–52% were severely injured, and 13–19% before reaching adulthood; and an estimated 80% succumbed to their injuries and died before reaching 40. It was thus theorized that Neanderthals employed a risky hunting strategy, though rates of cranial trauma are not significantly different between Neanderthals and Middle Paleolithic humans. Shanidar 1 shows signs of an amputation of the right arm likely due to a nonunion after breaking a bone in adolescence, osteomyelitis (a bone infection) on the left clavicle, an abnormal gait, vision problems in the left eye, and possible hearing loss. It is unlikely any of these are what ultimately killed him, however.

Likely due to advanced age (60s or 70s), La Chapelle-aux-Saints 1 had signs of Baastrup's disease, affecting the spine, and osteoarthritis. Shanidar 1, who likely died at about 40 or 50, was diagnosed with the most ancient case of diffuse idiopathic skeletal hyperostosis (DISH), a degenerative disease which restricts muscle movement, which likely led to his death.

Low population also led to low genetic diversity and probably inbreeding which could have led to inbreeding depression. The 13 inhabitants of Sidrón Cave collectively exhibited 17 birth defects likely due to this.

Neanderthals were likely subject to several infectious diseases and parasites. Humans likely transmitted diseases to them, one likely candidate the stomach bacteria Helicobacter pylori. A Neanderthal at Sidrón Cave showed evidence of a gastrointestinal Enterocytozoon bieneusi infection. The leg bones of La Ferrassie 1 feature lesions which are consistent with periostitis–inflammation of the tissue enveloping the bone–likely a result of hypertrophic osteoarthropathy, which is primarily caused by a chest infection or carcinoma.

Culture

Main article: Neanderthal behavior

Social structure

Group dynamics

Artist's reconstruction of a Neanderthal man and child

Neanderthals likely lived in much smaller and more sparsely distributed groups than Upper Paleolithic humans. Reliable evidence of Neanderthal group composition comes from Sidrón Cave and the footprints at Le Rozel: the former shows 7 adults, 3 adolescents, 2 juveniles, and an infant; whereas the latter, based on footprint size, shows juveniles and adults making up 80–90% of the group.

Children were likely weaned after 5 years – one year later than humans – probably to increase birth spacing. Indicated from various ailments resulting from high stress at a low age, such as stunted growth, children of both sexes were likely put to work directly after weaning. Upon reaching adolescence, an individual would likely have been expected to join in hunting large game.

Sites showing evidence of no more than three individuals may have represented nuclear families or temporary camping sites for special task groups (such as a hunting party). Bands likely moved between certain caves depending on the season, returning to the same locations generation after generation.

Inter-group relations

Denisova Cave in the Altai Mountains

A self-sustaining population which avoids inbreeding consists of about 450–500 individuals, which would necessitate these bands to interact with 8–53 other bands, but more likely the more conservative estimate given low population density. Analysis of the mtDNA of the Neanderthals of Sidrón Cave showed that the three men belonged to the same maternal lineage, while the three women belonged to different ones. This suggests that women "married out". However, the DNA of a Neanderthal from Denisova Cave shows that her parents were half-siblings, and the inhabitants of Sidrón Cave were likely highly inbred. Neanderthal groups probably rarely exchanged mates given the abundance of harmful genes.

Considering most Neanderthal artefacts were sourced no more than 5 km (3.1 mi) from the main settlement, it is unlikely these bands interacted very often. However, a skeleton from La Roche à Pierrot, France, showed a healed fracture on top of the skull apparently caused by a deep blade wound, and another from Shanadir Cave was found to have a rib lesion characteristic of projectile weapon injuries, which could be considered as evidence for conflict. Further, a few Neanderthal artefacts in a settlement could have originated 20, 30, 100, and 300 km (12.5, 18.5, 60, and 185 mi) away. It is possible that macro-bands formed, collectively encompassing 13,000 km² (5,000 sq mi), with each band claiming 1,200–2,800 km² (460–1,080 sq mi), maintaining strong alliances for mating networks or to cope with leaner times and enemies as is exhibited in the low-density hunter gatherer societies of the Western Desert of Australia. However, mapping of the Neanderthal brain indicates they may not have had the cognitive function required for complex social interactions and trade.

Social hierarchy

It is sometimes suggested, since they were hunters of challenging big game and lived in small groups, there was no sexual division of labour as seen in human societies. That is, men, women, and children all had to be involved in hunting, instead of just men hunting and women and children foraging which is a more efficient food-collecting system. However, in modern human societies, the higher the meat dependency, the higher the division of labour. Further, tooth wearing patterns in Neanderthal men and women suggest they commonly used their teeth for carrying items, but men exhibit more wearing on the upper teeth, and women the lower, implying some cultural differences in tasks.

File:Skeleton and restoration model of Neanderthal La Ferrassie 1.jpg

Skeleton and restoration model of La Ferrassie 1 at the National Museum of Nature and Science, Tokyo

It is controversially proposed that some Neanderthals wore decorative clothing or jewelry–such as a leopard skin or raptor feathers–to display elevated status in the group. The few number of Neanderthal graves found could be explained as only high-ranking members receiving an elaborate burial, as is the case for some contemporary human societies. An apparent cemetery of six or seven individuals at La Ferrassie may indicate they consciously identified as a single group.

A study looking at Neanderthal skeletons recovered from several natural rock shelters shows that, although they were recorded as bearing several trauma-related injuries, none of them had significant trauma to the legs which would debilitate movement. This might indicate that individuals who could not keep up with the group while moving from cave to cave were left behind. The high mortality rate indicates grandparents were rare. These all could indicate a culture based on the idea that self-worth derives from contributing food to the group; a debilitating injury would remove this self-worth and result in near-immediate death. In this hypothesis, elderly Neanderthals were given special burial rites for lasting so long.

Food

See also: Pleistocene human diet

Hunting and gathering

Red deer, the preferred game of Neanderthals

Neanderthals were probably apex predators, and fed predominantly on deer, namely red deer and reindeer, as they were the most abundant game, but also on ibex, wild boar, aurochs, and less frequently mammoth, straight-tusked elephant and woolly rhinoceros. Isotope studies of Neanderthals from two French sites showed similar profiles to other carnivores, suggesting that these populations ate fresh meat. Analysis of Neanderthal bone collagen from the Croatian Vindija Cave shows nearly all of their protein needs derived from animal meat. Living in a forested environment, Neanderthals were likely ambush hunters, getting close to and attacking their target–a prime adult–in a short burst of speed, thrusting in a spear at close quarters. Younger or wounded animals may have been hunted using traps, projectiles, or pursuit.

Neanderthal diet may have varied significantly region to region, with some communities subsisting primarily on a plant-based diet. Edible plant remains are recorded from several caves. For example, Neanderthals from Sidrón Cave in Spain, based on dental tarter, likely had a meatless diet of mushrooms, pine nuts, and moss, indicating they were forest foragers. Remnants from the Israeli Amud Cave indicates a diet of figs, palm tree fruits, and various cereals and edible grasses.

Dental tarter from Spy Cave indicates they had a meat-heavy diet including woolly rhinoceros and mouflon sheep, while also regularly consuming mushrooms. Neanderthal faecal matter from El Salt, Spain, dated to 50 kya–the oldest human faecal matter remains recorded–show elevated coprostanol levels (digested cholesterol indicating a meat-heavy diet) and elevated stigmastanol (deriving from plant matter). Evidence of cooked food plants–mainly legumes and, to a far lesser extent, acorns–were discovered in the Israeli Kebara Cave, possibly gathering plants in spring and fall and hunting in all seasons except fall, though the cave was probably abandoned in late summer to early fall. At the Iraqi Shanidar Cave, Neanderthals collected plants with various harvest seasons, indicating they scheduled returns to the area to harvest certain plants, and that they had complex food-gathering behaviors for both meat and plants.

Food preparation

Neanderthals probably could employ a wide range of cooking techniques, such as roasting, and they may have been able to heat up or boil soup, stew, or animal stock. The abundance of animal bone fragments at settlements may indicate the making of fat stocks from boiling bone marrow, possibly taken from animals which had already died of starvation. These methods would have substantially increased protein consumption, which was a major component of their nutrition to compensate for low carbohydrate intake. Neanderthal tooth size had a decreasing trend after 100 kya, which could indicate an increased dependence on cooking or the advent of boiling which would soften food.

Yarrow growing in Spain

At Sidrón Cave, Neanderthals likely cooked and possibly smoked food, as well as used certain plants–such as yarrow and camomile–as flavouring, though these plants may have instead been used for their medicinal properties. Further, the former hypothesis would assume a degree of cuisine complexity which lacks proper evidence. However, flavouring food may not require greatly enhanced humanlike cognitive or imaginative abilities, as Japanese macaques are known to dunk sweet potatoes and wheat in the ocean before eating them to give them a salty taste.

The archaeological record shows they commonly used animal hide and birch bark, and it is possible they used them to make cooking containers, though this is based largely on circumstantial evidence as neither fossilise well. It is possible the Neanderthals at Kebara Cave used the shells of the spur-thighed tortoise as containers.

They likely lacked any method of storing food, and had to eat whatever they hunted or foraged immediately.

Competition

Cave hyaena skeleton

Neanderthals and cave hyaenas may have exemplified niche differentiation, and actively avoided competing with each other. Though they both mainly targeted the same groups of creatures–deer, horses, and cattle–Neanderthals mainly hunted the former and cave hyaenas the latter two. Further, animal remains from Neanderthal caves indicate they preferred to hunt prime individuals, whereas cave hyaenas hunted weaker or younger prey and had a greater proportion of carnivore remains. In fact, cave hyaena caves are distinguished from Neanderthal caves by the higher abundance of carnivore remains. Nonetheless, cave hyaenas likely stole food and leftovers from Neanderthal campsites, and scavenged on dead Neanderthal bodies.

At Spy Cave, the remains of wolves, cave lions, and cave bears–which were all major predators of the time–indicate Neanderthals hunted their competitors to some extent, and that pressure from competition was rather high. Cave lions likely targeted horses, large deer and wild cattle; and the leopard primarily reindeer and roe deer; which heavily overlapped with Neanderthal diet. However, given the ferocity of these creatures and the lack of long-range weapons, confrontations likely would have resulted in a group display of yelling, arm waving, or stone throwing; or quickly gathering meat and abandoning a kill.^:120–143

Cannibalism

There are several examples of Neanderthals practising cannibalism occurring across their range. The first undisputed example came from Gran Dolina in 1999, and other examples were found at Sidrón Cave, Zafarraya in Spain; and the French Moula-Guercy Cave, Les Pradelles, and La Quina. For the five cannabalised Neanderthals at the Goyet Caves in Belgium, there is evidence that the upper limbs were disarticulated, the lower limbs defleshed and also smashed likely to extract bone marrow, the chest cavity disemboweled, the jaw dismembered, and the butchers used some bones to retouch their tools. The processing of Neanderthal meat at Goyet Caves is similar to how they processed horse and reindeer.

These cannibalistic tendencies have been explained as either ritual defleshing, for nutritional value, or as an act of war. Due to a small amount of cases, and the higher amount of cut marks seen on cannibalized individuals than animals (indicating inexperience), cannibalism was probably not a very common practice, and it may have only been done in times of extreme food shortages as in some historical cases in human history. It has also been suggested evidence of butchering was caused by pre-burial defleshing to prevent scavenging by wild animals or a foul smell. However, it is not uncommon to find Neanderthal remains eaten by an animal.

Art

Further information: Neanderthal behavior § Claims of art and adornment

Proposed Neanderthal jewelry: white-tailed eagle claw with striations at the Neanderthal site of Krapina, Croatia, circa 130,000 BP.

A large number of claims of Neanderthal art, adornment, and structures have been made which would show Neanderthals were capable of symbolic thought or were cognitively comparable to anatomically modern humans. However, many of these are ambiguously attributed as the dating interlaps with anatomically modern human presence in Europe. Among many others:

• Flower pollen on the body of pre-Neanderthal Shanidar 4, Iraq, had in 1975 been argued to be a flower burial, but the pollen could have also been deposited by natural events.
• In 1975, a mostly flat piece of flint with a bone pushed through a hole on the midsection–dating to 32, 40, or 75 kya–has been purported to resemble the upper half of a face, with the bone representing eyes–the Mask of la Roche-Cotard. It is contested whether it represents a face, or if it even constitutes as art.
• Châtelperronian beads have been attributed to Neanderthals, but the dating is uncertain and the beads may have been made by modern humans.
• Raptor and corvid bones were argued to show evidence of feather plucking by a 2012 study examining 1,699 ancient sites across Eurasia, which the authors controversially took to mean Neanderthals wore bird feathers as personal adornments.

The scratched floor of Gorham's Cave

• Deep scratches on the floor of Gorham's Cave, Gibraltar, were dated to older than 39 kya in 2012, which some have controversially interpreted as Neanderthal abstract art.
• Two 176,000-year-old stalagmite ring structures, several metres wide, were reported in 2016 more than 300 m (980 ft) from the entrance within Bruniquel Cave, France. Being so far inside the cave, this shows a high degree of proficiency in underground environments in Neanderthals. Other red-painted stalagmites in Spain were dated to 65,500 years ago.
• In 2015, a study argued that a number of 130,000-year-old eagle talons found in a cache near Krapina, Croatia along with Neanderthal bones, had been modified to be used as jewelry. A similar talon necklace was reported in 2019 at Cova Foradà in Spain.
• In 2017, incision-decorated raven bones from the Zaskalnaya VI (Kolosovskaya) Neanderthal site, Crimea, Micoquian industry dated to 43–38 kya were reported. Given there are 17 of these objects at seven different sites in the area, and the notches on all of them are more-or-less equidistant to each other, they are very unlikely to have originated from simple butchering.
• In 2018, red painted symbols comprising hand stencils, a ladder-shape figure, dots, discs, lines, and representations of animals on the cave walls of several caves across Spain 700 km (430 mi) apart, including La Pasiega, Cave of Maltravieso, Cave of El Castillo, and Doña Trinidad–were dated to be older than 66,000 years ago. This is at least 20,000 years prior to the arrival of anatomically modern humans in western Europe, and demonstrate Neanderthals were capable of symbolic behavior. However, the dating, and thus its attribution to Neanderthals, is contested.
• In 2018, perforated seashell beads and pigments that are at least 115 kya were found in Cave of Los Aviones in southeastern Spain.
• In 2018, an engraved flake flint was found in the grave a Neanderthal child in Crimea, Ukraine.

Technology

Levallois point – Beuzeville, France

Despite the apparent 150 kya stagnation in Neanderthal innovation, there is evidence that Neanderthal technology was more sophisticated than was previously thought. However, the high frequency of potentially debilitating injuries would have prevented very complex technologies from emerging, as a major injury would have impeded an expert's ability to effectively teach a novice.

Neanderthals made stone tools, and are associated with the Mousterian industry. The Levallois technique they adopted maximizes the cutting surface with the least amount of raw material (p. As a difficult-to-learn process, the technique may have been directly taught generation to generation rather than via purely observational learning. A Levallois point embedded in the vertebrae of an African wild ass indicated that a javelin had been thrown with a parabolic trajectory to disable the animal. They may also be associated with the Châtelperronian 45–40 kya, borrowing tool-making techniques from immigrating humans, though this is highly controversial.

Neanderthal were able to create fire, and, in a number of caves, evidence of hearths has been detected. Neanderthals likely considered air circulation when making hearths as a lack of proper ventilation for a single hearth can render a cave uninhabitable in several minutes. Abric Romaní rock shelter indicates eight evenly spaced hearths lined up against the rock wall, likely used to stay warm while sleeping, with one person sleeping on either side of the fire. At Cueva de Bolomor, with hearths lined up against the wall, the smoke flowed upwards to the ceiling, and led to outside the cave. In Grotte du Lazaret, smoke was probably naturally ventilated during the winter as the interior cave temperature was greater than the outside temperature; similarly, the cave was likely only inhabited in the winter.

It was long believed that an adhesive (birch bark tar) made by Neanderthals required to follow a complex recipe, and that it thus showed complex cognitive skills and cultural transmission. However, a 2019 study showed it can be made simply by burning birch bark on smooth vertical surfaces, such as a flat, inclined rock.

Mousterian hide scrapers

As opposed to the bone sewing needles and stitching awls of Upper Paleolithic humans, the only known Neanderthal tools that could have been used to fashion clothes are hide scrapers, which could have made items similar to blankets or ponchos. Nonetheless, Neanderthals would have needed to cover up most of their body. Contemporary humans would have covered 80–90%. Since human/Neanderthal admixture is known to have occurred in the Middle East, and no modern body louse species descends from Neanderthals–body lice only inhabit clothed individuals–it is possible Neanderthals in hotter climates did not wear clothes, or their lice were highly specialised.

Remains of Middle Paleolithic stone tools on Greek islands indicate early seafaring by Neanderthals in the Ionian Sea possibly starting as far back as 150,000–200,000 BCE. The oldest stone artefacts from Crete date to 130,000–107,000 BCE, Cephalonia 125,000 BCE, and Zakynthos 110,000–35,000 BCE. Here, they likely employed simple reed boats and made one-day crossings back and forth. Other Mediterranean islands include Sardinia, Melos, Alonnisos, and it is possible they crossed the Strait of Gibraltar and sailed to Naxos (though Naxos may have been connected to land). Their ability to engineer these boats and navigate through open waters speaks to their advanced cognitive and technical skills.

They appear to have had some knowledge of medicine. An individual at Sidrón Cave seems to have been self-medicating a dental abscess using poplar–which contains salicylic acid, the active ingredient in aspirin–and there were also traces of the antibiotic-producing Penicillium. They may have also used yarrow and camomile, and their bitter taste–which should act as a deterrent as it could indicate poison–means it was likely a deliberate act. In Kebara Cave, plant remains which have historically been used for their medicinal properties were found, including the common grape vine, the pistachios of the Persian turpentine tree, ervil seeds, and oak acorns.

Language

Reconstruction of the Kebara 2 skeleton at the Natural History Museum, London

The 1983 discovery of a Neanderthal hyoid bone–used in speech production in humans–in Kebara 2 almost identical to that of humans suggests Neanderthals were capable of speech. The prevailing hypothesis for a long time was that speech spontaneously developed very recently in humans, and some argued that the hyoid could have a different usage in Neanderthals, as it is simply used in tongue movement including while chewing. It was once thought Neanderthals were anatomically unable to produce quantal vowels, which are present in all human languages, because they had a large mouth to house the tongue and lacked necessity for a descended larynx but this is not a safe assumption to make, and the modern human vocal apparatus and thus vocal repertoire were likely already present in the ancestral H. heidelbergensis.

The degree of language complexity is difficult to establish, but given Neanderthals achieved some technical and cultural complexity, and interbred with humans, it is reasonable to assume they were at least fairly articulate, comparable to humans. A somewhat complex language–possibly using syntax–was likely necessary to survive in their harsh environment, needing to communicate about topics as locations, hunting and gathering, and tool-making techniques. However, they may have lacked mental synthesis, the human imaginative ability to craft effectively infinite ideas using a finite amount of words, a hallmark of behavioural modernity which appeared by about 70 kya, though behavioural modernity is now believed to have been a process started about 400 kya, and possibly also exhibited in Neanderthals.

Genetically, the FOXP2 gene in humans is identified to be very important in speech and language development. FOXP2 is present in Neanderthals, but not the modern human variant. Neurologically, they had an expanded Broca's area–operating the formulation of sentences, and speech comprehension–but 11 out of 48 genes which encode for language brainwaves had different methylation patterns between Neanderthals and modern humans, indicating a stronger ability in modern humans to express language.

Religion

See also: Paleolithic religion and History of religion

Funerals

Reconstruction of the grave of La Chapelle-aux-Saints 1 at the Musée de La Chapelle-aux-Saints

Claims that Neanderthals held funerals for their dead with symbolic meaning, are heavily contested. Even if the burial was intentional, it is not indicative of a religious belief of life after death, as such burial could have been the result of great emotion or to prevent scavengers.

The debate on Neanderthal funerals has been active since the 1908 discovery of La Chapelle-aux-Saints 1 in a small hole in a cave in southwestern France, very controversially attributed to have been buried in a symbolic fashion.

Another grave at Shanidar Cave was associated with the pollen of several flowers which may have been in bloom at the time of deposition–yarrow, Centaurea, ragwort, grape hyacinth, joint pine, and hollyhock. The medicinal properties of the plants led American archaeologist Ralph Solecki to claim that the man buried was some leader, healer, or shaman. However, it is also possible the pollen was deposited by a small rodent after the man's death.

The grave of Teshik-Tash 1 from Uzbekistan was associated with a circle of ibex horns, which was asserted by Sir Paul Mellars to indicate a ritualistic burial. However, the abundance of ibex horns in the vicinity casts doubt on this.

The grave of a Neanderthal child from Kiik-Koba from Crimea, Ukraine had a flint flake with some purposeful engraving on it, likely requiring a great deal of skill, and possibly made with some symbolic significance.

Cults

Cave bear skull

It was once asserted that the bones of the cave bear, particularly the skull, in some European caves were arranged in a specific order, indicating an ancient bear cult which killed bears and then ceremoniously arranged the bones. This would be consistent with bear-related rituals of human Arctic hunter gatherers, but the alleged peculiarity of the arrangement could also be well-explained by natural causes, and bias could be introduced as the existence of a bear cult would conform with the idea that totemism was the earliest religion, leading to undue extrapolation of evidence.

It was also once thought Neanderthals hunted, killed, and cannabalised other Neanderthals to use the skull as the focus of some ritual. In 1962, Italian palaeontologist Alberto Blanc believed a skull from Grotta Guattari, Italy had evidence of a swift blow to the head–indicative of ritual murder–and a precise and deliberate incising at the base to access the brain. He compared it to the victims of headhunters in Malaysia and Borneo, putting it forward as evidence of a skull cult. However, it is now thought to have been a result of cave hyaena predation. Though Neanderthals are known to have practiced cannibalism, there is unsubstantial evidence to suggest ritual defleshing.

Interbreeding

Main article: Archaic human admixture with modern humans

Interbreeding with modern humans

Further information: Neanderthal genetics

Reconstruction of the upper Paleolithic human Oase 2 with around 7.3% Neanderthal DNA (4–6 generations back)

The first Neanderthal genome sequence was published in 2010, and strongly indicated interbreeding between Neanderthals and humans. The genomes of all non-sub-Saharan-Africans contain Neanderthal DNA. Various estimates exist for the proportion: 1–4% in Eurasians, 3.4–7.9%, and 1.8–2.4% in Europeans and 2.3–2.6% in East Asians. Such low percentages indicate infrequent interbreeding. Of the inherited Neanderthal genome, 25% in Europeans and 32% in East Asians may be related to viral immunity. In all, approximately 20% of the Neanderthal genome appears to have survived in the modern human gene pool. However, due to their small population and resulting reduced effectivity of natural selection, Neanderthals mutated several weakly harmful mutations, which were introduced to and slowly selected out of the much larger human population; the initial hybridized population may have experienced up to a 94% reduction in fitness compared to contemporary humans. By this measure, Neanderthals may have substantially increased in fitness.

According to linkage disequilibrium mapping, the last Neanderthal gene flow into the modern human genome occurred 86–37 kya, but most likely 65–47 kya. However, the approximately 40 ka anatomically-modern human Oase 2 was found, in 2015, to have had 6–9% (point estimate 7.3%) Neanderthal DNA, indicating a Neanderthal ancestor up to four to six generations earlier, but this hybrid Romanian population does not appear to have made a substantial contribution to the genomes of later Europeans.

In 2016, the DNA of Altai Neanderthals showed evidence of interbreeding 100 kya, and interbreeding with a later dispersal of humans may have occurred as late as 120 kya in places such as the Levant. Palaeontologically, the earliest human remains outside of Africa occurs at Misliya Cave 194–177 kya, and Skhul and Qafzeh 120–90 kya. However, the Neanderthals of the German Hohlenstein-Stadel Cave have deeply divergent mtDNA compared to more recent Neanderthals, possibly due to introgression of human mtDNA between 316–219 kya, or simply because they were genetically isolated. Whatever the case, these first interbreeding event has not left any trace in modern human genomes.

Due to the absence of Neanderthal-derived mtDNA (which is passed on from mother to child) in modern populations, it has been suggested that the progeny of Neanderthal women who mated with modern human men were either rare, absent, or sterile–that is to say, admixture stems from the progeny of Neanderthal men with modern human women. Due to the lack of Neanderthal-derived Y-chromosomes in modern humans (which is passed on from father to son), it has also been suggested that the hybrids that contributed ancestry to modern populations were predominantly female, or the Neanderthal Y-chromosome was not compatible with humans and became extinct.

Detractors of the interbreeding model argue that the genetic similarity is only a remnant of a common ancestor instead of interbreeding. Anthropologist John D. Hawks has argued that the genetic similarity to Neanderthals may be the result of both common ancestry and interbreeding, as opposed to just one or the other.

Interbreeding with Denisovans

Chris Stringer's Homo family tree. The horizontal axis represents geographic location, and the vertical time in millions of years ago.

Though nDNA confirms that Neanderthals and Denisovans are more closely related to each other than they are to humans, Neanderthals and humans share a more recent maternally-transmitted mtDNA common ancestor, possibly due to interbreeding between Denisovans and some unknown hominid. The 400 kya Neanderthal-like hominids from Sima de los Huesos in northern Spain, looking at mtDNA, are more closely related to Denisovans than Neanderthals. Several Neanderthal-like fossils in Eurasia from a similar time period are often grouped into H. heidelbergensis, of which some may be relict populations of earlier hominids, which could have interbred with Denisovans. This is also used to explain an approximately 124,000-year-old German Neanderthal specimen with mtDNA that diverged from other Neanderthals (except for Sima de los Huesos) about 270 kya, while its genomic DNA indicated divergence less than 150 kya.

Sequencing of the genome of a Denisovan from Denisova Cave has shown that 17% of its genome derives from Neanderthal. This Neanderthal DNA more closely resembled that of a 120,000-year-old Neanderthal bone from the same cave than that of Neanderthals from Vindija Cave in Croatia or Mezmaiskaya Cave in the Caucasus, suggesting that interbreeding was local.

For the 90 ky old Denisova 11, it was found that her father was a Denisovan related to more recent inhabitants of the region, and her mother a Neanderthal related to more recent European Neanderthals at Vindija Cave, Croatia. The discovery of a first generation hybrid indicates interbreeding was very common between these groups, and Neanderthal migration across Eurasia likely occurred sometime after 120 kya.

Extinction

Main article: Neanderthal extinction

Map emphasizing the Ebro river in northern Spain

Neanderthals are thought to have died out between 41 and 39 kya. Though some Neanderthals in Gibraltar were dated to later than this–such as Zafarraya (30 kya) and Gorham's Cave (28 kya)–prompting a hypothesis of some Iberian refuge with the Ebro River providing a geographical barrier, these dates are likely incorrect as they were based on ambiguous artefacts instead of direct dating. A claim of Neanderthals surviving in a polar refuge in the Ural Mountains is loosely supported by Mousterian stone tools dating to 34–31 kya at a time when humans may not yet have colonised the northern reaches of Europe; however, human remains are known from the northern Siberian Mamontovaya Kurya site dating to 40 kya.

Whatever the cause of their extinction, Neanderthals were replaced by humans, indicated by near full replacement of Mousterian stone technology with human Aurignacian stone technology by 38 kya in the fossil record. Modern human remains dating to 45–43 kya have been found in Italy and Britain, and this migration of humans replaced Neanderthals. A 2019 reanalysis of 210 ky old skull fragments from the Greek Apidima Cave assumed to have belonged to a Neanderthal concluded that they belonged to a human, and DNA evidence indicates human contact with Neanderthals and admixture as early as 100 kya, meaning there were multiple human immigration events into Europe. A Neanderthal skull dating to 170 kya from Apidima Cave indicates humans were replaced by Neanderthals until their return about 40 kya.

Competition with modern humans

Replacement of Neanderthals by early modern humans.

Boule was the first person to suggest humans forcefully took Europe from the Neanderthals. Human expansion and Neanderthal contraction are correlated, possibly due to the competitive exclusion principle with humans outcompeting Neanderthals. However, largely hominid-free tropical Asia was colonised by humans by 60 kya, meaning European colonisation was, for some reason, delayed, and, though colder climate may have influenced immigration speed, it is possible the presence of Neanderthal settlements inhibited human expansion for some time.

Jared Diamond in his book The Third Chimpanzee said competitive replacement often occurs in human history when a more technologically advanced culture (humans) meets a less advanced culture (Neanderthals). Though Neanderthals likely exhibited modern behaviour, discrediting arguments of plain human superiority, the spread of grasslands and open steppe would have made human projectile weapons much more effective over Neanderthal short-range spears which were adapted to a forest environment; humans could push into colder areas with bigger game wearing their fitted clothes, which were more effective at insulating than Neanderthal ponchos; and raw material and animal remain sourcing in the southern Caucasus suggest that modern humans were able to use extensive social networks to acquire resources from a greater area in leaner times, whereas Neanderthals, since most of their stone artifacts were drawn from within 5 km (3.1 mi), likely restricted themselves to more local sources.

Anthropologist Pat Shipman suggested that domestication of the dog could have played a role in Neanderthals' extinction, or rather, a symbiosis with wolves long preceding domestication. She claims that humans, about 50–45 kya, evolved the whites of the eyes to allow for more effective non-verbal communications with wolves, and this gave humans an advantage over hunting. She also claims that Neanderthals did not have very prominent whites of the eyes, like the rest of the animal kingdom.^:214–226

Shanidar 3 died from complications from a stab wound, likely originating from a light-weight, long-range projectile, a technology that possibly only humans had, which implies Neanderthal/human violence. However, the Lower Paleolithic Schöningen spears and Neanderthal trauma consistent with habitual throwing indicate they were familiar with ranged weapons.

Climate change

Neanderthals extinction coincided with the start of a very cold period, and their low population left them vulnerable to any environmental change, with even a small drop in survival or fertility rates possibly quickly leading to their extinction. Their ultimate extinction coincides with Heinrich event 4, a period of intense cold and dry climate, and future Heinrich events are also associated with massive cultural turnovers where European human populations collapsed. This time was also characterised by the spread of grasslands and open steppe, which Neanderthal short-range technology was unsuited for, impeding their ability to hunt.

Graphic of the ash cloud from the Campanian Ignimbrite Eruption

Neanderthal extinction also coincides with the Campanian Ignimbrite Eruption in Italy around 40 kya, which caused a 2–4°C cooling event for a year and acid rain for several years. By that time, Neanderthal populations may have already been dwindling from other factors, and the eruption led to their final demise.

Disease

Humans may have introduced African diseases to Neanderthals which contributed to their extinction. Lacking immunity, compounded by an already low population, first contact may have been devastating to the Neanderthal population. Low genetic diversity may have also rendered fewer Neanderthals naturally immune to these new diseases.

Low population and inbreeding depression may have caused maladaptive birth defects, which could have contributed to their decline.

In New Guinea, due to cannibalistic practices, the population was decimated from transmissible spongiform encephalopathies (kuru) spread by ingestion of contaminated brains or contact with infected tools. A similar disease could have quickly spread through the small Neanderthal populations even through minimal contact with each other, given its high virulence and Neanderthal cannibalistic tendencies.

In popular culture

Main article: Neanderthals in popular culture

Cavemen in The Black Terror #16 (1946)

Neanderthals have been portrayed in popular culture including appearances in literature, visual media and comedy. The "caveman" archetype often mocks Neanderthals, and depicts them as primitive, hunchbacked, knuckle-dragging, club wielding, grunting, anti-social characters driven solely by animal instinct. "Neanderthal" can also be used as an insult.

In literature, they are sometimes depicted as brutish or monstrous, such as in H. G. Well's The Grisly Folk and Elisabeth Thomas' The Animal Wife, but also somewhat civilised, such as William Golding's The Inheritors, Björn Kurtén's Dance of the Tiger, and Jean M. Auel's Clan of the Cave Bear and her Earth's Children series.

See also

• Homo floresiensis
• Homo luzonensis
• Denisovan
• Early human migrations
• List of Neanderthal sites
• Neanderthals in Gibraltar

Further reading

• Reich, David (2018). Who We Are And How We Got Here – Ancient DNA and the New Science of the Human Past. Pantheon Books. ISBN 978-1101870327. {{cite book}}: Unknown parameter |titlelink= ignored (|title-link= suggested) (help)
• Diamond, Jared (April 20, 2018). "A Brand-New Version of Our Origin Story". The New York Times. Retrieved April 23, 2018.
• Derev'anko, Anatoliy P.; Powers, William Roger; Shimkin, Demitri Boris (1998). The Paleolithic of Siberia: new discoveries and interpretations. Novosibirsk: Institute of Anthropology and Ethnography. ISBN 978-0-252-02052-0. OCLC 36461622.
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External links

• New Portuguese skull may be an early relative of Neandertals – article by Ann Gibbons at Science, March 13, 2017.
• In Neanderthal DNA, Signs of a Mysterious Human Migration – article by Carl Zimmer, NY Times, July 4, 2017
• "Homo neanderthalensis". The Smithsonian Institution. February 14, 2010.
• "Neanderthal DNA". International Society of Genetic Genealogy. Archived from the original on June 17, 2006.: Includes Neanderthal mtDNA sequences
• Panoramio – The Neandertal foot prints' (photo of ≈25K years old fossilised footprints discovered in 1970 on volcanic layers near Demirkopru Dam Reservoir, Manisa, Turkey)
• Did better mothering defeat the Neanderthals?
• My Great-great-great Grandfather's a Neanderthal
• Ancient tryst fortified human immune system
• Neanderthal-human hybridisation hypothesis
• Neanderthal hybridisation and Haldane's rule
• Neanderthal Studies Professional Online Service (NESPOS) fossil overview
• Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016).
• "So, Were Neanderthals Us? Are eagle talons forever? (2019)