Neanderthal

Neanderthal Temporal range: Middle–Late Pleistocene 0.250–0.040 Ma PreЄ Є O S D C P T J K Pg N ↓
The Neanderthal skull of La Chapelle-aux-Saints 1
An approximate reconstruction of a Neanderthal skeleton. (The central ribcage, including the sternum, and parts of the pelvis are from modern humans.)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Family:	Hominidae
Genus:	Homo
Species:	H. neanderthalensis or Homo sapiens neanderthalensis
Binomial name
Homo neanderthalensis or Homo sapiens neanderthalensis King, 1864
Known Neanderthal range in Europe (blue), Southwest Asia (orange), Uzbekistan (green), and the Altai mountains (violet).
Synonyms
Homo mousteriensis[1] Palaeoanthropus neanderthalensis[2]

Neanderthals, or more rarely Neandertals,^{[lower-alpha 1]} (UK: /niˈændərˌtɑːl/, also US: /neɪ-, -ˈɑːn-, -ˌtɔːl, -ˌθɔːl/;^[6][7] named for the Neandertal region in Germany) were a species or subspecies of archaic humans in the genus Homo that became extinct about 40,000 years ago.^{[8][9][10][11][12][13]} Neanderthals and modern humans share 99.7% of their DNA^[14] and are hence closely related.^[15][16] (By comparison, both modern humans and Neanderthals share 98.8% of their DNA with their closest non-human living relatives, the chimpanzees.)^[14] Neanderthals left bones and stone tools in Eurasia, from Western Europe to Central and Northern Asia. Fossil evidence suggests Neanderthals evolved in Europe, separate from modern humans in Africa for more than 400,000 years. They are considered either a distinct species, Homo neanderthalensis,^[17][18][19] or more rarely^[20] as a subspecies of Homo sapiens (H. s. neanderthalensis).^[21][22]

Hundreds of lithic assemblages were created by Neanderthals in Europe and in Western Asia. Almost all of them are of the so-called Mousterian techno-complex, which begins c. 160,000 years ago when the makers started making fewer hand axes, and instead started to make tools out of flakes.^[23]

Compared to modern humans, Neanderthals had a lower surface-to-volume ratio, with shorter legs and a bigger body, in conformance with Bergmann's rule, as an energy-loss reduction adaptation to life in a high-latitude (i.e. seasonally cold) climate. Male Neanderthals had cranial capacities averaging 1,600 cm³ (98 cu in), females 1,300 cm³ (79 cu in),^[24][25] extending to 1,736 cm³ (105.9 cu in) in Amud 1.^[26] This is notably larger than the 1,250 to 1,400 cm³ (76 to 85 cu in) typical of modern humans. Males stood 164 to 168 cm (65 to 66 in) and females 152 to 156 cm (60 to 61 in) tall.^[27]

The Neanderthal genome project published papers in 2010 and 2014 stating that Neanderthals contributed to the DNA of modern humans, including most humans outside sub-Saharan Africa, as well as a few populations in sub-Saharan Africa, through interbreeding, likely between 50,000 and 60,000 years ago.^{[28][29][30][31]} Recent studies also show that some Neanderthals mated with ancestors of modern humans long before the "out of Africa migration" of present-day non-Africans, as early as 100,000 years ago.^[32] In 2016, research indicated that there were three distinct episodes of interbreeding between modern humans and Neanderthals: the first encounter involved the ancestors of non-African modern humans, probably soon after leaving Africa; the second, after the ancestral Melanesian group had branched off (and subsequently had a unique episode of interbreeding with Denisovans); and the third, involving the ancestors of East Asians only.^[33]

Geneticists first sequenced the entire genome of a Neanderthal in 2013 by extracting it from the phalanx bone of a 50,000-year-old Siberian Neanderthal.^[34][35][36]

Name

Neanderthals are named after one of the first sites where their fossils were discovered in the 19th century, about 12 km (7 mi) east of Düsseldorf, Germany, in the Feldhofer Cave, located in the Düssel River's Neander valley.^{[lower-alpha 2]} Thal is an older spelling of the German word Tal (with the same pronunciation), which means "valley" (cognate with English dale).^{[lower-alpha 3][38][39]}

Neanderthal 1 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".^[40] The binomial name Homo neanderthalensis – extending the name "Neanderthal man" from the individual type specimen to the entire group – was first proposed by the Anglo-Irish geologist William King in 1864, although that same year King changed his mind and thought that the Neanderthal fossil was distinct enough from humans to warrant a separate genus.^[4] Nevertheless, King's name had priority over the proposal put forward in 1866 by Ernst Haeckel, Homo stupidus.^[38] The practice of referring to "the Neanderthals" and "a Neanderthal" emerged in the popular literature of the 1920s.^[41]

The German pronunciation of Neanderthaler or 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/).^[42][43][44] 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/),^[45] although scientists typically use the /t/ as in German.^[46][47]

Classification

Scientists still dispute whether Neanderthals should be classified as a distinct species—Homo neanderthalensis—or as Homo sapiens neanderthalensis, placing Neanderthals as a subspecies of H. sapiens.^[48][49] DNA researcher Svante Pääbo referred to the ongoing "taxonomic wars" over whether Neanderthals were a separate species or subspecies as the type of debate that cannot be resolved, "since there is no definition of species perfectly describing the case."^[50]

During the early 20th century the prevailing view was heavily influenced by Arthur Keith and Marcellin Boule, who wrote the first scientific description of a nearly complete Neanderthal skeleton.^[51] Senior members of their respective national paleontological institutes and among the most eminent paleoanthropologists of their time,^[52][53] both men argued that the primitive traits of this skeleton meant it could not be a direct ancestor of Homo sapiens. This idea was reflected in Boule (1912)'s reconstruction of the Chapelle-aux-Saints 1 Neanderthal, now believed inaccurate, in which the skeleton was mounted in a crooked pose with bowed legs.^[54]

During the 1930s scholars Ernst Mayr, George Gaylord Simpson and Theodosius Dobzhansky reinterpreted the existing fossil record and came to different conclusions.^[55] Neanderthal man was classified as Homo sapiens neanderthalensis - an early subspecies contrasted with what was now called Homo sapiens sapiens. The unbroken succession of fossil sites of both groups in Europe was considered evidence of a slow, gradual evolutionary transition from Neanderthals to modern humans. Contextual interpretations of similar excavation sites in Asia lead to the hypothesis of multiregional origin of modern man in the 1980s.^[56]

Origins

Both Neanderthals and living humans are thought to have evolved from Homo erectus. In the earliest known migration wave into Eurasia dated to 1.81 million years ago (Ma), Homo erectus left Africa most probably via the Levant and reached Georgia (fossils of Dmanisi). Hominins had reached China by 1.7 Ma^[57] and Iberia (Spain) by 1.4 Ma.^[58] The discoverers of fragmented bones in Spain (Iberia) dated to 1.2 million years, assigned to a new species Homo antecessor, argue these are the remains of the ancestors of Neanderthals and of the older species Homo heidelbergensis, an interpretation rejected by most anthropologists.^[59]

A large number of molecular clock genetic studies place the divergence time of the Neanderthal and modern human lineages between 800,000 and 400,000 years ago.^{[60][61][62][63][64][65][66][67][36]} For this reason, most scholars believe Neanderthals descend, via Homo heidelbergensis, from another Homo erectus migration out of Africa that would have occurred in this time frame. Parts of the Homo erectus population that stayed in Africa would have evolved, perhaps through the intermediate Homo rhodesiensis, into early anatomically modern humans by 200,000 years ago or earlier.

Neanderthal traits are present in Homo heidelbergensis specimens beginning between 600,000 and 350,000 years ago.^{[68][69][70][71]} Conventionally, European hominins are called Neanderthals from c. 250,000 years ago.^[72] Because the quality of the fossil record greatly increases from 130,000 years ago onwards,^[73] specimens younger than this date make up the bulk of known Neanderthal skeletons and were the first whose anatomy was comprehensively studied. They are known as Classic Neanderthals.

Discovery

Neanderthal fossils were first discovered in 1829 in the Engis caves (the partial skull dubbed Engis 2), in what is now Belgium by Philippe-Charles Schmerling and the Gibraltar 1 skull in 1848 in the Forbes' Quarry, Gibraltar, both prior to the type specimen discovery in a limestone quarry in the Neandertal in Germany in August 1856, three years before Charles Darwin's On the Origin of Species was published.^[74]

The type specimen, dubbed Neanderthal 1, consisted of a skull cap, two femora, three bones of the right arm, two of the left arm, parts of the left ilium, fragments of a scapula, and ribs. The workers who recovered the objects originally thought them to be the remains of a cave bear. However, they eventually gave the material to amateur naturalist Johann Carl Fuhlrott, who turned the fossils over to anatomist Hermann Schaaffhausen.

To date, the bones of over 400 Neanderthals have been found.^[75]

Timeline of research

• 1829: A damaged skull of a Neanderthal child, Engis 2, is discovered in Engis, Netherlands (now Belgium).
• 1848: A female Neanderthal skull, Gibraltar 1, is found in Forbes' Quarry, Gibraltar, but its importance is not recognised.
• 1856: Limestone miners discover the Neanderthal type specimen, Neanderthal 1, in Neandertal, western Germany.
• 1864: William King is the first to recognise Neanderthal 1 as belonging to a separate species, for which he gives the scientific name Homo neanderthalensis. He then changed his mind on placing it in the Homo genus, arguing that the upper skull was different enough to warrant a separate genus since, to him, it had likely been "incapable of moral and theistic conceptions."^[4]
• 1880: The mandible of a Neanderthal child is discovered in a secure context in Šipka cave, in the Austro-Hungarian Empire (now Czechia), associated with cultural debris, including hearths, Mousterian tools, and bones of extinct animals.
• 1886: Two well-preserved Neanderthal skeletons are found at Spy, Belgium, making the hypothesis that Neanderthal 1 was only a diseased modern human difficult to sustain.^[76]
• 1899: Sand excavation workers find hundreds of fragmentary Neanderthal remains representing dozens of individuals on a hill in Krapina, in the Austro-Hungarian Empire (now Croatia).
• 1908: A very well preserved Neanderthal, La Chapelle-aux-Saints 1, is found in its eponymous site in France,^[77] said by the excavators to be a burial, a claim still heatedly contested.^[78][79][80] For historical reasons it remains the most famous Neanderthal skeleton.^[73]:15
• 1912: Marcellin Boule publishes his now discredited influential study of Neanderthal skeletal morphology based on La Chapelle-aux-Saints 1.
• 1953–1957: Ten Neanderthal skeletons are excavated in Shanidar Cave, Iraqi Kurdistan, by Ralph Solecki and colleagues.
• 1975: Erik Trinkaus's study of Neanderthal feet strongly argues that Neanderthals walked like modern humans.
• 1981: The site of Bontnewydd, Wales yielded an early Neanderthal tooth, the most north-western Neanderthal remain ever.
• 1987: Israeli Neanderthal Kebara 2 is dated (by TL and ESR) to 60,000 BP, thus later than the Israeli anatomically modern humans dated to 90,000 and 80,000 BP at Qafzeh and Skhul.
• 1994: The site of Sidrón Cave, Spain, is discovered where the remains of 12 males and females were to be found. Mitochondrial DNA studies would show that the adult males were genetically related, but the adult females were not, suggesting female exogamy.^[81][82]
• 1997: Matthias Krings et al. are the first to amplify Neanderthal mitochondrial DNA (mtDNA) using a specimen from Feldhofer grotto in the Neander valley.^[83]
• 1997–2000: A small part of the skull of Neanderthal 1, the Neanderthal type fossil discovered in 1856, is found in a dump of limestone mining debris near the original discovery site.^[84]
• 1998: The body of a c. 24,000 year old early Upper Paleolithic child is discovered at Abrigo do Lagar Velho, Portugal, and is described as presenting a mosaic of anatomically modern human and more archaic features, reminiscent of Neanderthals.^[85]
• 2005: The Max Planck Institute for Evolutionary Anthropology and associated institutions launch the Neanderthal genome project to sequence the Neanderthal nuclear genome.^[86]
• 2010: 1–4% of the DNA of living non-African humans are found by the Max Planck Institute to likely come from Neanderthals,^[29][87] a result confirmed in 2012,^[88][89] and refined to 1.5–2.1% in 2014.^[36]
• 2013: In the midst of a hundred-year old debate over the existence of Neanderthal deliberate burials, a team of French researchers reasserted a heavily contested 1908 claim that the Chapelle-aux-Saints 1 skeleton was deliberately buried.^[90]
• 2014: Some researchers express worry that almost all theories for the Neanderthals' extinction assume that there is something modern humans had that Neanderthals did not.^[91]
• 2014: The most comprehensive dating ever of Neanderthal bones and tools from hundreds of sites in Europe is carried out. It suggested that European Neanderthals died out between 41,000 and 39,000 years ago, which coincides with the start of a very cold period in Europe and is no more than 5,000 years after anatomically-modern Homo sapiens reached the continent.^[13][92]

Habitat and range

Early Neanderthals, living before the Eemian interglacial (130 ka), are poorly known and come mostly from European sites. From 130 ka onwards, the quality of the fossil record increases dramatically. From then on, Neanderthal remains are found in Western, Central, Eastern, and Mediterranean Europe,^[93] as well as Southwest, Central, and Northern Asia up to the Altai Mountains in Siberia. No Neanderthal has ever been found outside Western Eurasia, namely neither to the south of Jerusalem (Shuqba), nor further east than Kazakhstan (Denisova, Russia), nor to the north of Wales (Bontnewydd),^[94][95] although it is difficult to assess the limits of their northern range because glacial advances destroy most human remains, the Bontnewydd tooth being exceptional. Middle Palaeolithic artifacts have been found up to 60° N on the Russian plains.^[96]

There likely never were more than 70,000 Neanderthals at any given time.^[97]

Anatomy

Neanderthal anatomy differed from modern humans in that they had a more robust build and distinctive morphological features, especially on the cranium, which gradually accumulated more derived aspects as it was described by Marcellin Boule,^[98] particularly in certain isolated geographic regions. These include shorter limb proportions, a wider, barrel-shaped rib cage, a reduced chin, and a large nose, being at the modern human higher end in both width and length,^{[lower-alpha 4]} and started somewhat higher on the face than in modern humans.^[72] Evidence suggests they were much stronger than modern humans, with particularly strong arms and hands,^[99][100] while they were comparable in height; based on 45 long bones from at most 14 males and 7 females, Neanderthal males averaged 164 to 168 cm (65 to 66 in) and females 152 to 156 cm (60 to 61 in) tall.^[27] Samples of 26 specimens in 2010 found an average weight of 77.6 kg (171 lb) for males and 66.4 kg (146 lb) for females.^[101] A 2007 genetic study suggested some Neanderthals may have had red hair and blond hair, along with a light skin tone.^[102]

Gregory Cochran and Henry Harpending, in the book The 10,000 Year Explosion, investigated whether it is accurate to depict Neanderthals as having hair pattens similar to anatomically modern humans. They concluded that, "We don’t yet know for sure, but it seems likely that, as part of their adaptation to cold, Neanderthals were furry. Chimpanzees have ridges on their finger bones that stem from the way that they clutch their mothers' fur as infants. Modern humans don’t have these ridges, but Neanderthals do."^[103]

In The Spread of Modern Humans in Europe (2002) John F Hoffecker, writes "Neanderthal sites show no evidence of tools for making tailored clothing. There are only hide scrapers, which might have been used to make blankets or ponchos. This is in contrast to Upper Paleolithic (modern human) sites, which have an abundance of eyed bone needles and bone awls. Moreover, microwear analysis of Neanderthal hide scrapers shows that they were used only for the initial phases of hide preparation, and not for the more advanced phases of clothing production.^[104]

A 2013 study of Neanderthal skulls suggests that their eyesight may have been better than that of modern humans, owing to larger eye sockets and larger areas of the brain devoted to vision.^[105]

Neanderthals are known for their large cranial capacity, which at 1,600 cm³ (98 cu in) is larger on average than that of modern humans. One study has found that Neanderthal brains were more asymmetric than other hominid brains.^[106] In 2008, a group of scientists produced a study using three-dimensional computer-assisted reconstructions of Neanderthal infants based on fossils found in Russia and Syria. It indicated that Neanderthal and modern human brains were the same size at birth, but that by adulthood, the Neanderthal brain was larger than the modern human brain.^[107] They had almost the same degree of encephalization (i.e. brain to body size ratio) as modern humans.^[108][109]

The Neanderthal skeleton suggests they consumed 100 to 350 kcal (420 to 1,460 kJ) more per day than male modern humans of 68.5 kg (151 lb) and females of 59.2 kg (131 lb).^[110]

Behavior

Neanderthals made stone tools,^[111] used fire,^[112] and were hunters. The consensus on their behaviour ends here.

It had actually long been debated whether Neanderthals were hunters or scavengers.^[72] Most available evidence suggests they were apex predators,^[113][114] and fed on red deer, reindeer, ibex, wild boar, aurochs and on occasion mammoth, straight-tusked elephant and rhinoceros.^[72][115] However, while they were largely carnivorous,^[116][117] new studies suggest Neanderthals occasionally used vegetables as fall-back food.^[114][118] In 2010, an isotope analysis of Neanderthal teeth found traces of cooked vegetable matter, and a 2014 study of Neanderthal coprolites (fossilized feces) found substantial amounts of plant matter.^[116][119] Dental analysis of specimens from Spy, Belgium and El Sidrón, Spain^[120] in 2017 argued these Neanderthals had a wide-ranging diet, and that those "from El Sidrón showed no evidence of meat eating" at all and seemed to have lived on "a mixture of forest moss, pine nuts and a mushroom known as split gill".^[121]

The size and distribution of Neanderthal sites, along with genetic evidence, suggests Neanderthals lived in much smaller and more sparsely distributed groups than anatomically-modern Homo sapiens.^[122][123] The bones of twelve Neanderthals were discovered at El Sidrón cave in the Atapuerca Mountains of Spain. They are believed to have been a group killed and butchered about 50,000 years ago. Analysis of the mtDNA showed that the three adult males belonged to the same maternal lineage, while the three adult females belonged to different ones. This suggests a social structure where males remained in the same social group and females "married" out.^[124]

The bones of the El Sidron group show signs of defleshing, suggesting that they were victims of cannibalism.^[124] The St. Césaire 1 skeleton discovered in 1979 at La Roche à Pierrot, France, showed a healed fracture on top of the skull apparently caused by a deep blade wound, suggesting interpersonal violence.^[125]

Claims that Neanderthals deliberately buried their dead, and if they did, whether such burials had any symbolic meaning,^{[73]:158–160} are heavily contested.^{[79][126][80]} The debate on deliberate Neanderthal burials has been active since the 1908 discovery of the well-preserved Chapelle-aux-Saints 1 skeleton in a small hole in a cave in southwestern France. In this controversy's most recent installment, a team of French researchers reinvestigated the Chapelle-aux-Saints cave and in January 2014 reasserted the century-old claim that the 1908 Neanderthal specimen had been deliberately buried,^[90] and this has in turn been heavily criticised.^[78]

Claims of art and adornment

Upon Higham et al.'s (2010)^[127] publication of new radiocarbon dates shedding doubt on the association of Châtelperronian beads with Neanderthals, Paul Mellars wrote that “the single most impressive and hitherto widely cited pillar of evidence for the presence of complex ‘symbolic’ behavior among the late Neanderthal populations in Europe has now effectively collapsed”.^[128] This conclusion, however, is controversial, and others such as Jean-Jacques Hublin and colleagues have re-dated material associated with the Châtelperronian artefacts^[129] and used proteomic evidence to restate the challenged association with Neanderthals.^[130]

There exists a very large number of other claims of Neanderthal art, adornment, and structures. These are often taken by the media as showing Neanderthals were capable of symbolic thought,^[131][132] or were “mental equals” to anatomically modern humans.^[133][134] As evidence of symbolism, none of them are widely accepted,^[135] although the same is true for Middle Palaeolithic anatomically modern humans. Among many others:

• Flower pollen on the body of pre-Neanderthal Shanidar 4, Iraq, had in 1975 been argued to be a flower burial.^[136] Once popular, this theory is no longer accepted.^[137][138]
• Pigmented shells from Murcia, Spain, were argued in 2009 to be Neanderthal make-up containers.^[139]
• Bird bones were argued to show evidence for feather plucking in a 2012 study examining 1,699 ancient sites across Eurasia, which the authors controversially^[140] took to mean Neanderthals wore bird feathers as personal adornments.^[141]
• Deep scratches were found in 2012 on a cave floor underlying Neanderthal layer in Gorham's Cave, Gibraltar, which some have controversially^[142] interpreted as art.^[143]
• Two 176,000-year-old stalagmite ring structures, several metres wide, were reported in 2016 more than 300 metres from the entrance within Bruniquel Cave, France. The authors claim artificial lighting would have been required as this part of the cave is beyond the reach of daylight and that the structures had been made by early Neanderthals, the only humans in Europe at this time.^[144]

Genome

Background

Early investigations concentrated on mitochondrial DNA (mtDNA), which, owing to strictly matrilineal inheritance and subsequent vulnerability to genetic drift, is of limited value in evaluating the possibility of interbreeding of Neanderthals with Cro-Magnon people.

In 1997, geneticists were able to extract a short sequence of DNA from Neanderthal bones.^[145] The extraction of mtDNA from a second specimen was reported in 2000, and showed no sign of modern human descent from Neanderthals.^[146]

In July 2006, the Max Planck Institute for Evolutionary Anthropology and 454 Life Sciences announced that they would sequence the Neanderthal genome over the next two years. This genome was expected to be roughly the size of the human genome, three-billion base pairs, and share most of its genes. It was hoped the comparison would expand understanding of Neanderthals, as well as the evolution of humans and human brains.^[147]

Svante Pääbo has tested more than 70 Neanderthal specimens. The Neanderthal genome is almost the same size as the human genome and is identical to ours to a level of 99.7% by comparing the accurate order of the nitrogenous bases in the double nucleotide chain.^[148] From mtDNA analysis estimates, the two shared a common ancestor about 500,000 years ago. An article^[149] appearing in the journal Nature has calculated they diverged about 516,000 years ago, whereas fossil records show a time of about 400,000 years ago.^[150] A 2007 study pushes the point of divergence back to around 800,000 years ago.^[151]

Edward Rubin of the Lawrence Berkeley National Laboratory states recent genome testing of Neanderthals suggests human and Neanderthal DNA are some 99.5% to nearly 99.9% identical.^[152][153]

Interbreeding with modern humans

On November 16, 2006, Lawrence Berkeley National Laboratory issued a press release suggesting Neanderthals and ancient humans probably did not interbreed.^[154] Edward M. Rubin, director of the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the Joint Genome Institute (JGI), sequenced a fraction (0.00002) of genomic nuclear DNA (nDNA) from a 38,000-year-old Vindia Neanderthal femur. They calculated the common ancestor to be about 353,000 years ago, and a complete separation of the ancestors of the groups about 188,000 years ago.^[155]

Their results show the genomes of modern humans and Neanderthals are at least 99.5% identical, but despite this genetic similarity, and despite the two groups having coexisted in the same geographic region for thousands of years, Rubin and his team did not find any evidence of any significant interbreeding between the two. Rubin said, "While unable to definitively conclude that interbreeding between the two species of humans did not occur, analysis of the nuclear DNA from the Neanderthal suggests the low likelihood of it having occurred at any appreciable level."^[155]

In 2008 Richard E. Green et al. from Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, published the full sequence of Neanderthal mitochondrial DNA (mtDNA) and suggested "Neanderthals had a long-term effective population size smaller than that of modern humans."^[156]

In the same publication, it was disclosed by Svante Pääbo that in the previous work at the Max Planck Institute, "Contamination was indeed an issue," and they eventually realized that 11% of their sample was modern human DNA.^[157][158] Since then, more of the preparation work has been done in clean areas and 4-base pair 'tags' have been added to the DNA as soon as it is extracted so the Neanderthal DNA can be identified.

With 3 billion nucleotides sequenced, analysis of about ⅓ showed no sign of admixture between modern humans and Neanderthals, according to Pääbo. This concurred with the work of Noonan from two years earlier. The variant of microcephalin common outside Africa, which was suggested to be of Neanderthal origin and responsible for rapid brain growth in humans, was not found in Neanderthals. Nor was the MAPT variant, a very old variant found primarily in Europeans.^[157]

However, an analysis of a first draft of the Neanderthal genome by the same team released in May 2010 indicates interbreeding may have occurred.^[29][87] "Those of us who live outside Africa carry a little Neanderthal DNA in us," said Pääbo, who led the study. "The proportion of Neanderthal-inherited genetic material is about 1 to 4 percent [later refined to 1.5 to 2.1 percent]^[36]. It is a small but very real proportion of ancestry in non-Africans today," says Dr. David Reich of Harvard Medical School, who worked on the study. This research compared the genome of the Neanderthals to five modern humans from China, France, sub-Saharan Africa, and Papua New Guinea.^[87]

This indicates a gene flow from Neanderthals to modern humans, i.e., interbreeding between the two populations. Since the three non-African genomes show a similar proportion of Neanderthal sequences, the interbreeding must have occurred early in the migration of modern humans out of Africa, perhaps in the Middle East. No evidence for gene flow in the direction from modern humans to Neanderthals was found. Gene flow from modern humans to Neanderthals would not be expected if contact occurred between a small colonizing population of modern humans and a much larger resident population of Neanderthals. A very limited amount of interbreeding could explain the findings, if it occurred early enough in the colonization process.^[87]

It is suggested that 20 percent of Neanderthal DNA survived in modern humans, notably expressed in the skin, hair, and diseases of modern people.^[159] Modern human genes involved in making keratin—the protein found in skin, hair, and nails—have specially high levels of Neanderthal DNA.^[159] For example, around 66% of East Asians contain the Neanderthal skin gene, while 70% of Europeans contain the Neanderthal gene which affects skin colour. POU2F3 is found in around 66 percent of East Asians, while the Neanderthal version of BNC2, which affects skin color, among other traits, is found in 70 percent of Europeans. Neanderthal are the variants in genes that affect the risk of several diseases, including lupus, biliary cirrhosis, Crohn's disease, and type 2 diabetes. 8% of Neanderthal DNA comes from an unknown group of archaic humans, tantalizing hints of unknown groups from Asia and Africa that left genes in Denisovans and modern humans, respectively.^[159][160] The genetic variant of the MC1R gene linked to red hair in Neanderthals has not been found in modern humans, hence red hair may be an example of convergent evolution.^{[161][162][163]}

While interbreeding is viewed as the most parsimonious interpretation of the genetic discoveries, the authors point out they cannot conclusively rule out an alternative scenario, in which the source population of non-African modern humans was already more closely related to Neanderthals than other Africans were, because of ancient genetic divisions within Africa.^[87] Other studies carried out since the sequencing of the Neanderthal genome have cast doubt on the level of admixture between Neanderthals and modern humans, or even as to whether the groups interbred at all. One study has asserted that the presence of Neanderthal or other archaic human genetic markers can be attributed to shared ancestral traits between the lineages originating from a 500,000-year-old common ancestor.^{[164][165][166][167]}

Among the genes shown to differ between present-day humans and Neanderthals were RPTN, SPAG17, CAN15, TTF1, FOXP2 and PCD16.^[87]

More recent research suggests that Neanderthal–Homo sapiens sapiens interbreeding appears to have occurred asymmetrically among the ancestors of modern-day humans, and that this is a possible rationale for differing frequencies of Neanderthal-specific DNA in the genomes of modern humans. In 2015, researchers Benjamin Vernot and Joshua Akey at the University of Washington conclude in a paper in the American Journal of Human Genetics that the relatively greater quantity of Neanderthal-specific DNA in the genomes of individuals of East Asian descent (than those of European descent) cannot be explained by differences in selection.^[168] They further suggest that "two additional demographic models, involving either a second pulse of Neandertal gene flow into the ancestors of East Asians or a dilution of Neandertal lineages in Europeans by admixture with an unknown ancestral population" are parsimonious with their data.^[168] Similar conclusions were reached in a paper published in the same publication by researchers Bernard Kim and Kirk Lohmueller at UCLA: "Using simulations of a broad range of models of selection and demography, we have shown that this hypothesis [that the greater proportion of Neandertal ancestry in East Asians than in Europeans is due to the fact that purifying selection is less effective at removing weakly deleterious Neandertal alleles from East Asian populations] cannot account for the higher proportion of Neandertal ancestry in East Asians than in Europeans. Instead, more complex demographic scenarios, most likely involving multiple pulses of Neandertal admixture, are required to explain the data."^[169]

In a subsequent interview, Dr. Lohmueller did note that these findings go against the commonly-held perception that Neanderthals were mostly localized to modern-day Europe and western Asia: "It’s very hard to put these findings into spatial context. The key idea is that there would have to have been some additional interbreeding events involving East Asians, but not Europeans. These interbreeding events could have been directly between Neanderthals and East Asians, maybe in some other indirect way."^[170] Vernot also noted that "[H]umans have been constantly migrating throughout their history—this makes it hard to say exactly where interactions with Neanderthals occurred. It's possible, for example, that all of the interbreeding with Neanderthals occurred in the Middle East, before the ancestors of modern non-Africans spread out across Eurasia. In the model from the paper, the ancestors of all non-Africans interbred with Neanderthals, and then split up into multiple groups that would later become Europeans, East Asians. Shortly after they split up, the ancestors of East Asians interbred with Neanderthals just a little bit more."^[170]

Studies published in March 2016 suggest that modern humans bred with hominins, including Neanderthals, on multiple occasions.^[171] Another study in April 2016 found differences between modern human and Neanderthal Y chromosomes that, they postulated, could cause female Homo sapiens sapiens to miscarry male babies that had Neanderthal fathers.^[172] This could explain why no modern man had to date been found with a Neanderthal Y chromosome.^[173] Melanesians and Australoid populations show evidence of only one interbreeding event, possibly about 100,000 years ago, occurring in the Middle East, Europeans show a second event, which may also be of Middle Eastern origin, occurring possibly 50,000 years ago, while East Asians show an additional third interbreeding event possibly 30,000 years ago occurring in Siberia. Evidence that Neanderthal genomic material is often found amongst genes of the immune system suggests that some of the interbreeding may have secured resistance to diseases that Neanderthal populations had bred resistance to.^[171]

In 2016 researchers reported that they had found Human DNA in the genome of a female Neanderthal from the Altai mountains region near the border between Mongolia and Russia. They calculated that the mating must have taken place about 100,000 years ago.^[174]

Epigenetics

In April 2014, a first glimpse into the epigenetics of the Neanderthal was obtained with the publication of the full DNA methylation of the Neanderthal and the Denisovan.^[175][176] The reconstructed DNA methylation map allowed researchers to assess gene activity levels throughout the Neanderthal genome and compare them to modern humans. One of the major findings focused on the limb morphology of Neanderthals. Gokhman et al. found that changes in the activity levels of the HOX cluster of genes were behind many of the morphological differences between Neanderthals and modern humans, including shorter limbs, curved bones and more.^[176]

Extinction

According to a 2014 study by Thomas Higham and colleagues of organic samples from European sites, Neanderthals died out in Europe between 41,000 and 39,000 years ago.^{[lower-alpha 5]} New dating in Iberia, where Neanderthal dates as late as 28,000 years had been reported, suggests evidence of Neanderthal survival in the peninsula after 42,000 years ago is almost non-existent.^[11]

Anatomically modern humans arrived in Mediterranean Europe between 45,000 and 43,000 years ago, so the two different human populations shared Europe for several thousand years.^[177][178] The exact nature of biological and cultural interaction between Neanderthals and other human groups is contested.^[179]

Possible scenarios for the extinction of the Neanderthals are:

1. Neanderthals were a separate species from modern humans, and became extinct (because of climate change or interaction with modern humans) and were replaced by modern humans moving into their habitat between 45,000 and 40,000 years ago.^[180] Jared Diamond has suggested a scenario of violent conflict and displacement.^[181]
2. Neanderthals were a contemporary subspecies that bred with modern humans and disappeared through absorption (interbreeding theory).
3. Volcanic catastrophe: see Campanian Ignimbrite Eruption

Climate change

About 55,000 years ago, the climate began to fluctuate wildly from extreme cold conditions to mild cold and back in a matter of decades. Neanderthal bodies were well-suited for survival in a cold climate—their stocky chests and limbs stored body heat better than the Cro-Magnons. Neanderthals died out in Europe between 41,000 and 39,000 years ago, apparently coinciding with the start of a very cold period.^[13][183] Raw material sourcing and the examination of faunal remains by Adler et al. (2006) in the southern Caucasus suggest that modern humans may have had a survival advantage during this period, being able to use social networks to acquire resources from a greater area. They found that in both the Late Middle Palaeolithic and Early Upper Palaeolithic more than 95% of stone artifacts were drawn from local material, suggesting Neanderthals restricted themselves to more local sources.^[184]

Coexistence with modern humans

In November 2011 tests conducted at the Oxford Radiocarbon Accelerator Unit in England on what were previously thought to be Neanderthal baby teeth, which had been unearthed in 1964 from the Grotta del Cavallo in Italy, were identified as the oldest modern human remains discovered anywhere in Europe, dating from between 43,000 and 45,000 years ago.^[185] Given that the 2014 study by Thomas Higham of Neanderthal bones and tools indicates that Neanderthals died out in Europe between 41,000 and 39,000 years ago, the two different human populations shared Europe for as long as 5,000 years.^[13] Nonetheless, the exact nature of biological and cultural interaction between Neanderthals and other human groups has been contested.^[179]

Modern humans co-existed with them in Europe starting around 45,000 years ago and perhaps even earlier. Neanderthals inhabited that continent for a long period of time before the arrival of modern humans. These modern humans may have introduced a disease that contributed to the extinction of Neanderthals, and that may be added to other recent explanations for their extinction. When Neanderthal ancestors left Africa roughly 100,000 years earlier they adapted to the pathogens in their European environment, unlike modern humans who adapted to African pathogens. This transcontinental movement is known as the Out of Africa model. If contact between humans and Neanderthals occurred in Europe and Asia the first contact may have been devastating to the Neanderthal population, because they would have had little if any immunity to the African pathogens. More recent historical events in Eurasia and the Americas show a similar pattern, where the unintentional introduction of viral, or bacterial pathogens to unprepared populations has led to mass mortality and local population extinction.^[186] The most well-known example of this is the arrival of Christopher Columbus to the New World, which brought and introduced foreign diseases when he and his crew arrived to a native population who had no immunity.

Anthropologist Pat Shipman, of Pennsylvania State University, suggested that domestication of the dog could have played a role in Neanderthals' extinction.^[187]

Interbreeding hypotheses

An alternative to extinction is that Neanderthals were absorbed into the Cro-Magnon population by interbreeding. This would be counter to strict versions of the Recent African Origin, since it would imply that at least part of the genome of Europeans would descend from Neanderthals.

Hans Peder Steensby, while strongly emphasising that all modern humans are of mixed origins, proposed the interbreeding hypothesis in 1907, in the article Race studies in Denmark.^[189] He held that this would best fit current observations, and attacked the widespread idea that Neanderthals were ape-like or inferior.

The most vocal proponent of the hybridization hypothesis is Erik Trinkaus of Washington University.^[190] Trinkaus claims various fossils as products of hybridized populations, including the child of Lagar Velho, a skeleton found at Lagar Velho in Portugal.^{[191][192][193]} In a 2006 publication co-authored by Trinkaus, the fossils found in 1952 in the cave of Peștera Muierii, Romania, are likewise claimed as descendants of previously hybridized populations.^[194]

Genetic research has asserted that some admixture took place.^[195] The genomes of all non-Africans include portions that are of Neanderthal origin,^[196][197] due to interbreeding between Neanderthals and the ancestors of Eurasians in Northern Africa or the Middle East prior to their spread. Rather than absorption of the Neanderthal population, this gene flow appears to have been of limited duration and limited extent. An estimated 1.5 to 2.1 percent^[36] of the DNA in Europeans and Asians (French, Chinese and Papua probands) is non-modern, and shared with ancient Neanderthal DNA. This DNA is absent in Sub-Saharan Africans (Yoruba people and San probands).^[87] Ötzi the iceman, Europe's oldest preserved mummy, was found to possess an even higher percentage of Neanderthal ancestry.^[198] The two percent of Neanderthal DNA that lives on in Europeans and Asians is not the same in all Europeans and Asians: In all, approximately 20% of the Neanderthal genome appears to survive in the modern human gene pool.^[199]

2012 genetic studies seem to suggest that modern humans may have mated with "at least two groups" of archaic humans: Neanderthals and Denisovans.^[200] Some researchers suggest admixture of 3.4–7.9% in modern humans of non-African ancestry, rejecting the hypothesis of ancestral population structure.^[201] Detractors have argued and continue to argue that the signal of Neanderthal interbreeding may be due to ancient African substructure, meaning that the similarity is only a remnant of a common ancestor of both Neanderthals and modern humans and not the result of interbreeding.^[166][202] John D. Hawks has argued that the genetic similarity to Neanderthals may indeed be the result of both structure and interbreeding, as opposed to just one or the other.^[203]

While some modern human nuclear DNA has been linked to the extinct Neanderthals, no mitochondrial DNA of Neanderthal origin has been detected,^[83] which in primates is always maternally transmitted. This observation has prompted the hypothesis that whereas female humans interbreeding with male Neanderthals were able to generate fertile offspring, the progeny of female Neanderthals who mated with male humans were either rare, absent or sterile.^[204] However, some researchers have argued that there is evidence of possible interbreeding between female Neanderthals and male modern humans.^{[174][205][206]}

Specimens

Notable European Neanderthals

Remains of more than 300 European Neanderthals have been found. For the most important, see List of human evolution fossils.

• Neanderthal 1: The first Neanderthal specimen found during mining in August 1856. It was discovered in a limestone quarry at the Feldhofer grotto in Neanderthal, Germany. The find consisted of a skull cap, two femora, three right arm bones, two left arm bones, ilium, and fragments of a scapula and ribs.
• La Chapelle-aux-Saints 1: Called the Old Man, a fossilized skull discovered in La Chapelle-aux-Saints, France, by A. and J. Bouyssonie, and L. Bardon in 1908. Characteristics include a low vaulted cranium and large browridge typical of Neanderthals. Estimated to be about 60,000 years old, the specimen was severely arthritic and had lost all his teeth long before death, leading some to suggest he was cared for by others.
• La Ferrassie 1: A fossilized skull discovered in La Ferrassie, France, by R. Capitan in 1909. It is estimated to be 70,000 years old. Its characteristics include a large occipital bun, low-vaulted cranium and heavily worn teeth.
• Le Moustier 1: One of the rare nearly complete Neanderthal skeletons to be discovered, it was excavated by a German team in 1908, at Peyzac-le-Moustier, France. Sold to a Berlin museum, the post cranial skeleton was bombed and mostly destroyed in 1945, and parts of the mid face were lost sometime after then. The skull, estimated to be less than 45,000 years old, includes a large nasal cavity and a less developed brow ridge and occipital bun than seen in other Neanderthals. The Mousterian tool techno-complex is named after its discovery site.

Notable Southwest Asian Neanderthals

Remains of more than 70 Southwest Asian Neanderthals have been found. For a complete list see List of Southwest Asian Neanderthals.

• Shanidar 1 to 10: Eight Neanderthals and two pre-Neanderthals (Shanidar 2 and 4) were discovered in the Zagros Mountains in Iraqi Kurdistan. One of the skeletons, Shanidar 4, was once thought to have been buried with flowers, a theory no longer accepted. To Paul B. Pettitt the "deliberate placement of flowers has now been convincingly eliminated", since "[a] recent examination of the microfauna from the strata into which the grave was cut suggests that the pollen was deposited by the burrowing rodent Meriones tersicus, which is common in the Shanidar microfauna and whose burrowing activity can be observed today".^[207]
• Amud 1: A male adult Neanderthal, dated to roughly 45,000 BP, and one of several found in a cave at Nahal Amud, Israel. At 178 cm (70 in), it is the tallest known Neanderthal. It also has the largest cranial capacity of all extinct hominins: 1,736 cm³.^[72][208]
• Kebara 2: A male adult post-cranial skeleton, dated to roughly 60,000 BP, that was discovered in 1983 in Kebara Cave, Israel. It has been studied extensively, for its hyoid, ribcage, and pelvis are much better preserved than in all other Neanderthal specimens.

Notable Central Asian Neanderthal

• Teshik-Tash 1: An 8–11 year old skeleton discovered in Uzbekistan by Okladnikov in 1938. This is the only fairly complete skeleton discovered to the east of Iraq. Okladnikov claimed it was a deliberate burial, but this is debated.

Chronology

This section describes bones with Neanderthal traits in chronological order.

Mixed with H. heidelbergensis traits

• > 350 ka: Sima de los Huesos c. 500:350 ka ago^[209][210]
• 350–200 ka: Pontnewydd 225 ka ago.
• 200–135 ka: Atapuerca,^[211] Vértesszőlős, Ehringsdorf, Casal de'Pazzi, Biache, La Chaise, Montmaurin, Prince, Lazaret, Fontéchevade

H. neanderthalensis fossils

• 130–50 ka: Krapina, Saccopastore skulls, Malarnaud, Altamura, Gánovce, Denisova, Okladnikov, Pech de l'Azé, Tabun 120–7002100000000000000♠100±5 ka,^[212] Shanidar 1 to 9 80–60 ka, La Ferrassie 1 70 ka, Kebara 60 ka, Régourdou, Mt. Circeo, Combe Grenal, Erd 50 ka, La Chapelle-aux Saints 1 60 ka, Amud I 7001530000000000000♠53±8 ka,^[213][214] Teshik-Tash.
• In radiocarbon range, > 50 ka: Le Moustier, Feldhofer, La Quina, l'Hortus, Kulna, Šipka, Saint Césaire, Bacho Kiro, El Castillo, Bañolas, El Sidron (48±3 cal ka),^[215] Arcy-sur-Cure, Châtelperron, Figueira Brava, Mezmaiskaya (41±1 cal ka),^[10] Zafarraya, Vindija, Velika Pećina.

Homo sapiens sapiens with archaic traits reminiscent of Neanderthals

• < 35 Pestera cu Oase 35 ka, Mladeč 31 ka, Pestera Muierii 30 ka (n/s),^[216] Lapedo Child 24.5 ka.

Popular culture

Neanderthals have been portrayed in popular culture including appearances in literature, visual media and comedy. Early 20th century artistic interpretations often presented Neanderthals as beastly creatures, emphasizing hairiness and rough, dark complexion.^[217]

See also

Notes

References

Journals

• Boë, Louis-Jean; Heim, Jean-Louis; Honda, Kiyoshi; Maeda, Shinji (2002). "The potential Neandertal vowel space was as large as that of modern humans". Journal of Phonetics. 30 (3): 465–84. doi:10.1006/jpho.2002.0170. 
• Lieberman, Philip (October 2007). "Current views on Neanderthal speech capabilities: A reply to Boe et al. (2002)". Journal of Phonetics. 35 (4): 552–63. doi:10.1016/j.wocn.2005.07.002. 
• Serre, David; Langaney, André; Chech, Mario; Teschler-Nicola, Maria; Paunovic, Maja; Mennecier, Philippe; Hofreiter, Michael; Possnert, Göran; Pääbo, Svante (2004). "No Evidence of Neandertal mtDNA Contribution to Early Modern Humans". PLoS Biology. 2 (3): e57. PMC 368159 . PMID 15024415. doi:10.1371/journal.pbio.0020057. 
• Wild, Eva M.; Teschler-Nicola, Maria; Kutschera, Walter; Steier, Peter; Trinkaus, Erik; Wanek, Wolfgang (2005). "Direct dating of Early Upper Palaeolithic human remains from Mladeč". Nature. 435 (7040): 332–5. Bibcode:2005Natur.435..332W. PMID 15902255. doi:10.1038/nature03585. 
• Zilhão, João; Davis, Simon J. M.; Duarte, Cidália; Soares, António M. M.; Steier, Peter; Wild, Eva (2010). Hawks, John, ed. "Pego do Diabo (Loures, Portugal): Dating the Emergence of Anatomical Modernity in Westernmost Eurasia". PLoS ONE. 5 (1): e8880. Bibcode:2010PLoSO...5.8880Z. PMC 2811729 . PMID 20111705. doi:10.1371/journal.pone.0008880. Lay summary – ScienceDaily (January 27, 2010). 

Bibliography

• 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. 
• Lunine, Jonathan I. (2013). Earth: Evolution of a Habitable World. Cambridge University Press. 327. ISBN 978-0-521-85001-8. 

Further reading

• Sankararaman, Sriram; Mallick, Swapan; Dannemann, Michael; Prüfer, Kay; Kelso, Janet; Patterson, Nick; Reich, David (2014). "The genomic landscape of Neanderthal ancestry in present-day humans". Nature. 507 (7492): 354–357. Bibcode:2014Natur.507..354S. PMC 4072735 . PMID 24476815. doi:10.1038/nature12961. 
• Vattathil, S.; Akey, J.M. (2015). "Small amounts of archaic admixture provide big insights into human history". Cell. 163 (2): 281–284. PMID 26451479. doi:10.1016/j.cell.2015.09.042. 

External links

Wikimedia Commons has media related to Homo neanderthalensis.

Wikibooks has a book on the topic of: Introduction to Paleoanthropology

Wikispecies has information related to: Homo neanderthalensis

Wikisource has the text of the 1905 New International Encyclopedia article Neanderthal Man.

• Kreger, C. David (June 30, 2000). "Homo neanderthalensis". ArchaeologyInfo.com. Retrieved May 23, 2009. 
• O'Neil, Dennis (May 12, 2009). "Evolution of Modern Humans: Neandertals". Retrieved May 23, 2009. 
• 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. 
• "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 fossilized 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 hybridization and Haldane's rule
• Hominin interbreeding and the evolution of human variation – article by Kwang Hyun Ko, published online July 16, 2016
• Neanderthal Studies Professional Online Service (NESPOS) fossil overview
• Human Timeline (Interactive)—Smithsonian, National Museum of Natural History (August 2016).