Neanderthal

From Citizendium
Jump to navigation Jump to search
This article is developed but not approved.
Main Article
Discussion
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
 
This editable, developed Main Article is subject to a disclaimer.

The Neanderthals [1] are an extinct nonmodern hominid that come chronologically extremely close to the modern era, becoming extinct less than 30,000 years ago. The classic Neanderthal traits are found from about 75,000 to 35,000 years ago, but it is difficult to date the initial appearance of this species. The best estimate comes from the Moula Guercy site in France dating the earliest appearance of Neanderthals to 120,000 years ago.

For decades the Neanderthals have been viewed as a hunched, hairy, stumbling, stupid cave man that lived tens of thousands of years ago. This image can be highly attributed to Marcellin Boule,[2] a French paleoanthropologist at the beginning of the twentieth century. In 1908, at La Chapelle-aux-Saints in southwestern France (see #Sites and Significant Fossils below) a nearly complete male skeleton was excavated and Boule spent the better part of three years examining this specimen. The man was old in terms of Neanderthal standards, aged between 40 and 50 years old, and suffered from severe arthritis in his spine. This fact was discovered long after Boule described him as hunched over, practicing an inefficient shuffling gait type of bipedalism. His preconceptions, opposed to scientific objectivity, resulted in the misconception about the genus as a whole. Today this is reflected in not only in normal perception but shown in popular culture.

Discovery

Neandertal, Germany.

Neander Valley, literally translated in German as "Neandertal", is in the German Federal State of North Rhine-Westphalia, where the river Düssel meets the Rhine. It is here that the first fossil to be recognized as a different kind of human was discovered, arguably marking the beginning of the field of paleoanthropology. Miners in search of limestone blasted open the entrance to a small cave, Feldhofer Cave (also called Feldhofer Grotto) where an array of fossilized bones were found. The miners mostly discarded the bones, but sat some aside to bring to a local school teacher, believing them to be bones from a cave bear. Included in this group was the skullcap that would eventually become the holotype of Homo neanderthalensis (see #Sites and Significant Fossils below). The fossil displayed a long skull with very pronounced brow ridges above the orbits (eye sockets). In addition, the miners came across two femora, five arm bones, part of the left ilium, portions of a scapula and multiple ribs. These fossils were delivered to Johann Fuhlrott, a school teacher and amateur natural historian.[3]

Fuhlrott recognized the importance of the bones and quickly brought them to the professor of anatomy at the University of Bonn, Hermann Schaaffhausen. After much examination, the pair presented their discovery of the Neanderthaler ("Neanderthal Man")[3] in June of 1857 where they highlighted what they believed to be the great antiquity of the specimen. Unable to accurately describe the unusual cranial characteristics of the Neanderthaler, Schaaffhausen concluded that this individual must have belonged to an ancient aboriginal tribe residing in Germany before modern inhabitation, an anti-deluvian ancient race before the biblical flood, implying it was simply an inferior version of our own species.

This explanation, along with the emphasis Schaaffhausen and Fuhlrott placed on the great antiquity of the Neanderthaler, was not well received in the scientific community. Many opposing views surfaced, one of the most recognized denied the age of the specimen and classified him as a Mongolian horseman soldier. The unusual profile would fit because of multiple head injuries sustained by a warrior, who would also have been impoverished, malnourished and prone to developing diseases that would cause deformities. It was suggested that the brow ridges could have formed if the soldier was constantly frowning. Another well received hypothesis was by a leading German scientist Rudolf Virchow. Virchow argued that the abnormal appearance of the skull was due to pathology[3], it was simply a particularly unfortunate affliction this individual suffered and there was no chance it was a different type of human. This idea became less plausible as more specimens were found. Between this time and 1914 many new discoveries like Schaaffhausen's Neanderthaler were made in Germany, France, Belgium as well as Croatia. Following World War I, more discoveries were made in Italy, the Ukraine, the Near East and Central Asia. In 1861 William King acknowledged the primitive traits as well as the alignment with modern humans and named the genus Homo neanderthalensis. Today, Homo neanderthalensis is the most well studied of all the archaic Homo.[4]

Morphology

Cranial and Dental Morphology

Homo neanderthalensis has a skull that differs from modern humans (homo sapiens) on many points of interest. Overall, the structure is longer, lower and more robust.

  • Cranial: Braincase and face
    • The average brain volume has been estimated at 1520cc, larger than the 1350cc of modern Homo sapiens. This is often misleading because when compared to the average body size of each species, modern Homo sapiens have a proportionally larger brain, even if the Neanderthal brain is physically larger.[2] Endocasts point toward Neanderthal dominance on the cerebral, indicating the right and left spheres of the brain were specialized, in line with modern humans.[2]
    • A relatively large face that is forwardly situated and characteristically has midfacial prognathism, as if it is being pulled forward by the nose.
    • Cheekbones are swept back behind a large and open nasal cavity. They feature triangular peninsulas of bone that project into the nasal opining from both sides, increasing the surface area on mucus-producing membranes that, research suggests, aide in warming and humidifying the cold and dry air associated with the tundra environment of Neanderthals. [5]
    • On the rear of the skull is what is commonly referred to as an "occipital bun" where an increase in bone surface area allows for more muscle attachment. It is at this point where certain neck muscles anchor into pits, the supeainias fossae. This adaptation leads to increased power in the neck and shoulders.
    • Large, double arched bony brow ridges above the orbits. The brow ridges are functionally linked to the retracting forehead, as the forehead becomes less and less vertical, the brow ridges become necessary in order to absorb the heavy stress generated in the face during chewing.
  • Dentition: Specialized chewing apparatus.
    • Very large incisors with reduced size in the rest of the dentition, also evidence of scraping animal and plant material against front teeth, leading to heavy wear.[2] This labial wear has been hypothesized to be due to Neanderthals holding animal hides in their teeth while cutting, scraping or processing them.
    • Upper incisors built up by ridges on the side, "shovelled" or described as shovel shaped.[2]
    • Taurodont post canine dentition resulting in an enlarged pulp cavity and fused roots that are not independent of one another.
    • The back teeth often have additional cusps and taurodont ("bull-toothed") roots[2] produced by a delayed turning-in of the roots during dental formation. This results in the molars being poorly or only slightly separated from each other.[2]
    • Very powerful musculature for a forwardly placed jaw. Increased mastoid tuberosity where temporal muscles attach on each side of the skull towards the rear of the braincase. The posterior temporal muscles aide in the use of the front teeth, hypothesized to increase productivity of scraping with the front teeth, thought to be very important to Neanderthal culture.
    • A retromolar gap between M3, the last molar, and the ascending mandibular ramus, the extension of the jaw bone.
    • A bony prominence next to the mandibular foramen, the hole that admits the mandibular nerve from the brain. This relates to the attachment of the sphenomandibular ligament which suspends and rotates the lower jaw, playing a role in stabilizing a large jaw during muscle actions.

Skeletal Morphology

In general Neanderthals were is 4" shorter than modern Homo sapiens and approximately 15 pounds heavier. The males averaged around 5'7" and the females 5'3". The largest male on record was discovered in Amud, Israel at nearly 5'11", and the smallest female at La Ferrassie, France at 5'1".[2]

They were relatively wide with a stocky and broad torso and short extremities, with bowing of the limb bones. This general body shape reduces skin surface area and retains heat better than an anatomically modern Homo sapiens, key to its cold weather environment. This is characterized as "hyperpolar" and is considered to be the most extremely anatomically adapted species among all hominids.[4] Neanderthals exhibit musculoskeletal hypertrophy[5], generally the bones are robust with large areas for muscle attachment.

  • Large shoulder and elbow joints
  • Large and wide rib cage
  • Long clavicle
  • Wide scapula with more muscle attachments at the rear
  • Bowed and short forearm leading to a strong gripping hand with wide fingertips.
  • Wide hips with an outwardly rotating, large hip joint
  • Rounded, curved and thick-walled femur shaft
  • A relatively acute angle between the shaft and neck of the femur when compared to modern Homo sapiens
  • Large and thick patella (knee)
  • Short and flattened, thick-walled tibia
  • Large ankle joint
  • Wide and strong toe bones

Unlike all of these features which follow a trend of increased muscle attachment and wider bones, the superior pubic ramus, the upper-front part of the pelvis, is much more gracile than expected. Being relatively long, thin and flattened, it had been suggested that it may have increased the birth canal to assist a small bodied mother birth a large headed infant, the large brain size needing a longer gestation period. But since this feature is also found in male specimens, it is believed to have widened the pelvis at the front to assist in rotating the blades of the pelvis outward along with the hip joint.[2][3]

Climate

Generally, the Neanderthals seemed able to inhabit areas where the mean winter temperatures fell well below the freezing point, probably between -5 and 5 degrees Fahrenheit.[4] This was the world of the ice age, with very little vegetation and the domain of megafauna.

During their 200,000 year existence, the Neanderthals encountered many fluctuations in climate and environment. A quarter of a million years ago marked the beginning of an interglacial stage, yet conditions were not interglacial maxima.[2] This variety of repeated climactic passes, ranging from temperate cool to glacial, are considered critical in the adaptation and selection process of the classic Neanderthal features that arise approximately 130,000 years ago. At this time, an interglacial period abruptly raised sea levels and receded ice caps. This period was a world of megafauna[2], straight- tusked elephants, narrow-nosed rhinoceroses, wooly mammoths and wooly rhinos inhabiting the same areas as the rising Neanderthals. The early glacial period between 115,000 and 75,000 years ago represents a downturn in temperature that would have worked against the survival of many megafauna species of the north Neanderthal environments.[2] At this time, sea level fell as ice sheets grew, exposing small amounts of continental shelf. The next early glacial phase increased the surface of the continental shelf as temperatures dropped even more up to 30,000 years ago. Tree coverage nearly disappeared in the northern latitudes[2] and large frozen ground features such as ice wedges emerged. During this phase, particularly around 40,000 years ago, there was a series of small climactic fluctuations before the trend turned rapidly toward temperature decline,[2] presenting difficult situations for the Neanderthals to adapt to over short periods of time. As the Neanderthals were going extinct around 30,000 years ago, during a full glacial period, the climate was marked by a global drop in sea levels and an even greater decline in overall temperature.


Climatic conditions Estimated years ago Western Eurasia Hominid Evolution
Mainly temperate or cool, with some glacial intervals,
Large oceans, small ice caps
250,000-180,000 Transitional 'archaic Homo sapiens
to early Neanderthals in Europe.
Full glacial with some milder intervals.
Small oceans, large ice caps
180,000-130,000 Early Neanderthals, fixation on many
Neanderthal features in Europe.
Interglacial Last interglacial, warm conditions.
Large oceans, small ice caps
130,000-115,000 Neanderthals in Europe and perhaps also
in Middle East.
Early glacial: temperate/cool 115,000-75,000 Neanderthals (?) and Moderns in the
Middle East
Early glacial: cool/glacial
Ice caps increasing
75,000-30,000 Neanderthals extinct at end of this period.
Moderns appear in Europe.
Full glacial 30,000-13,000
Late glacial 13,000-10,000
Postglacial (present interglacial) 10,000- present

This table is a composite of fig. 19 and fig. 20 taken from In Search of the Neanderthals: Solving the Puzzle of Human Origins by Christopher Stringer and Clive Gamble, New York: Thames and Hudson Ltd., 1993.

Culture

Mousterian tradition

The earliest examples of the Mousterian tradition date back to 150,000 years ago in France, possibly even earlier, and can be found as recently as 27,000 years ago in Spain.[3] It is characteristic of the Middle Paleolithic beginning 250,000 years ago, earlier tool industries including Oldowan and Acheulian being classified as the Lower Paleolithic. Named after the French site Le Moustier, Mousterian is not a replacement of the former Levallois technique but merely a refinement, producing smaller and more precise flakes from the core.[5] This technique is considered the first standardization of tool production. The French prehistorian François Bordes recognized the highly variable specimens attributed to the Mousterian tradition and defines 63 different tools for either cutting, slicing, piercing, scraping, sawing or pounding. [5] This variability over time and geographic range is often attributed to locally available raw materials, as well as their climate and environment as a whole.[3] Bordes suggests categorizing the 63 tools in terms of five coexisting Neanderthal Cultures. Lewis and Sally Binford view these five groupings as five sets of tool kits that represent the same group, not separate localized cultures.[5] Another hypothesis comes from Harold Dibble in 1987 who believes that the large frequency of notably different tools is not evidence for many task specific types but instead is showing us different stages in the use of the tool.[5] It requires hundreds of blows to shape and sharpen the edge of a flake once it has been removed from its core, and this edge would require refinement after frequent use and dulling of the tool.[5] The 63 tools are not distinct, but rather showing us how Neanderthals prolonged the use of their Mousterian stone tools as long as possible.

The Mousterian tool industry is immediately followed, usually seen as a transitional period, by the Châtelperronian tool industry. Being very short lived, evidence only ranging from 36,000 to 32,000 years ago, it welcomes in the Upper Paleolithic. There is much overlap between Mousterian and Châtelperronian only diverging with the presence of long, thin blade tools that are exactly what characterize the Aurignacian[5] tradition of later anatomically modern Homo sapiens of the Upper Paleolithic. It is viewed as a mixing of techniques of the Neanderthals and fully modern Homo sapiens that inhabited the same locations.[3] This hybridized technology is found primarily in France, seen at Neanderthal sites such as Saint-Césaire and Arcy-sur-Cure.[5]

Subsistence

Neanderthals are classically thought of as subsiding primarily on animal meat. This idea has overshadowed the fact that plants and vegetation provided some percent of the diet of Neanderthals, but direct evidence for plant resources is scarcer and less interesting to our culture. Instead, there is abundant evidence for animal protein as a large part of their diet, a fact that is not surprising considering the tundra like environment, riddled with megafauna, where the Neanderthals lived.

A large amount of gazelle and fallow dear were uncovered in association with Neanderthals at the Kebara Cave in Israel, showing there was a breadth of animal subsistence for the cave inhabitants.[5] There is evidence of both burning and cut marks on the animal bone, but carbonized seeds of wild peas found in the hearth showed that in addition to the large amount of animal food, locally available vegetable foods were used.[5]

In Iran, Curtis Marean and SooYeum Kim excavated the Kobeh Cave in 1998 and discovered the upper and lower limbs of wild goats, the meat rich portions of the animal.[5] It is unlikely these cuts of meat would be left behind by other carnivores for Neanderthals to scavenge, and cut marks are present. In addition, percussion marks made from being struck by a stone hammer are present, presumably in order to get at the protein rich marrow inside the bone.[5]

Chemical analysis of bones has also been conducted to determine Neanderthal diet. Through nitrogen isotope analysis, the ratio of carbon and nitrogen can be determined and compared to other known herbivores, omnivores and carnivores. Herbivores occupy the lower end of the spectrum of nitrogen isotopes, and Neanderthals are associated much more closely with the carnivores. This technique was carried out at Vindija Cave in Croatia and placed the Neanderthals in line with contemporary carnivores such as saber-toothed cats.[5] Overall, it appears that Neanderthals ate eat a lot of meat. This technique is imperfect and may not reveal the entire spectrum of Neanderthal diet, but instead shows that the vast majority of dietary protein for the Neanderthals was derived from meat. Analysis of the collagen of the bone would be swamped with the animal protein and is often misinterpreted as them being nearly completely carnivorous, when instead it more suggests they were highly omnivorous with protein intake from animal meat.

Compassion and Community

A surprising amount of Neanderthal specimens seem to have survived to old age in extremely poor condition. Eric Trinkaus compared the type and sheer quantity of Neanderthal bone breaks to be similar to that of modern rodeo riders. This idea relates to their hunting style, suggesting that they sustained many injuries while being close to their prey. By examining preserved teeth, it has been estimated that about 57% of Neanderthals had dental hypoplasia, where enamel growth is halted during tooth development often associated with vitamin deficiency, infectious disease or trauma.[6] It is unquestionable that Neanderthals experienced a lot of hardship during their typical lifespan, yet somehow many survived for many years. Enamel hypoplasia often occurs during early childhood, as do the formation of Harris lines - cracks of the end of long limb bones resulting from dietary deficiency during childhood developing years[5] that are often found in Neanderthals. This shows that it was not only the stress of hunting and adulthood, but early life was also very traumatic for Neanderthal individuals.

This longevity is largely attributed to compassion and social care for incapacitated individuals.[7] The "Old Man" of La Chapelle-aux-Saints, studies by Boule, only had two teeth left when he died. The specimen from Shadinar Cave, Iraq (#Sites and Significant Fossils) Shanidar 1 took a crushing blow to his left orbit, probably blinding him and potentially causing brain damage; he also had one withered arm and had lost his other forearm entirely. All of this degenerative trauma left him incapable of moving efficiently and he would only have survived between 40 and 45 years with the assistance of others. There is a pattern seen across sites of old age specimens with disease or trauma who would have required care from others in their community.

Symbolism, Rituals and Burials

The Middle Paleolithic culture has been paralleled with modern humans, suggesting that the Neanderthals performed ritualistic behavior and had the emotional capacity that is in line with modern Homo sapiens.[8] Not only have many examples of intentional burial been discovered, but evidence of a bear burial at Regourdou, burned and broken bones implying cannibalism, cave bear skulls found at Drachenloch,[8] and many others suggest ritualistic and symbolic behavior showing a human-like awareness and spirituality.


Burials

Most solid evidence we have is for intentional burials, but the intention the Neanderthals had for burying their dead is questioned. Were Neanderthals displaying a sense of the afterlife and the importance of death, or merely disposing of bodies to remove them from living areas and to not attract predators? Many believe that the Neanderthals had no foresight into their burials, it was not ceremonial or may even have had significance that is impossible for anthropologists to imagine or comprehend.[3] One problem in deciphering this practice is many of the sites were excavated so long ago that proper precautions were not taken to determine intentional burial. Many sites, including La Ferrassie and Saint- Césaire have no evidence of a grave pit, but in contrast there is a very clear pit at Chapelle-aux-Saints.

Many of the uncovered burials reveal the Neanderthal skeleton in in a flexed position, crouched with knees drawn up to chest and occasionally the head pillowed on an arm.[5][3] Burying the dead in this position is practiced by modern cultures to mimic the fetus of the womb, in a sense being birthed into the afterlife. Simple grave goods are found alongside the bodies, usually stone or bone artifacts, occasional ochre used as red pigmentation that would suggest ritualistic behavior, and common animal bone. It is difficult to determine whether these grave goods, not being elaborate or exotic but rather daily fare, were intentionally placed to accompany the dead in an afterlife or whether they just circumstantially ended up in the grave pit or near the dead body.[5]

Between 1957 and 1961 Shanidar Cave (#Sites and Significant Fossils) was excavated and nine burials were found. The specimen Shanidar 4 has drawn the most attention and is referred to as the "flower burial".[2] Along with the intentionally flexed body, lots of fossilized pollen was recovered indicating plants and flowers were inserted into the grave pit. It is unlikely the flowers were blown in, and some others have argued a rodent could have played a part. Considering the types of pollen are mostly medicinal which would be ill-tasting to rodents and unlikely to be highly concentrated, there is little doubt that the flowers were put there by human agency. The purpose, ritualistic or otherwise, is impossible to decipher.


Symbolism

There is very little evidence of art and symbolism on behalf of the Neanderthals. That element of culture is generally associated with fully modern humans in the past 50,000 years or so, but there are rare occurrences of art. Examples of grooved or perforated animal teeth, polished ivory, and geometrically incised bone and ivory can be found at Neanderthal sites[5] and represent the closest thing that could be called artistic and symbolic expression of the Neanderthals. In France at the site Acry-sur-Cure is one of the largest caches of potential artistic objects, with over 142 perforated objects that may have been used as personal ornamentation.[5]


Cannibalism

At the Krapina site in Croatia, over a thousand Neanderthal bones have been uncovered with a MNI (minimum number of individuals) of over 80. What is intriguing about this site is that the bones are smashed to pieces and over 800 cut marks have been documented on them. Gorjanović concluded from his excavations here that this fragmentary state of human remains was due to the practice of cannibalism.[3] It is difficult to deny that this is strong evidence for cannibalistic practice among the Neanderthals. Yet processing and eating one another may have many ritualistic implications, or they may have simply been preparing the dead for burial. The truth is lost with the Neanderthals, but the practice is obvious. At the Moula Guercy site in France there are clearly butchered Neanderthal remains that are disassembled much like the Neanderthals butchered their deer, suggesting that they were eating the flesh as they ate the deer flesh.

Homo sapiens neanderthalensis or Homo neanderthalensis?

This may seem like an irrelevant question, but whether or not we classify Neanderthals in only our genus or as a subspecies of Homo sapiens is extremely interesting in terms of ancestry. It is largely believed that Neanderthals are not a direct ancestor of Homo sapiens, being largely contemporaneous instead. if we label them Homo neanderthalensis, their line dies and ends there. But if we instead put them in our own species, the contact between Neanderthals and anatomically modern Homo sapiens becomes much more intriguing, for they would have the potential to interbreed. This debate is intensive and deeply rooted in discussion over a Replacement Model versus a Multiregional Model for the rise of fully modern humans.

The Replacement Model basically consists of two Out-of-Africa events for the spread of ancient hominids. All the evidence is toward the oldest modern humans arising in Africa and migrating out to Eurasia.[5] Upon coming into contact with archaic Homo, anatomically modern Homo sapiens are selected for and the archaics die out in competition with no possible interbreeding. If the Replacement Model is true, then Neanderthals would not be part of our species and should be classified as Homo neanderthalensis. In contrast the Multiregional model only credits early Homo erectus for an Out-of-Africa event around 1.7 million years ago. Modern Homo sapiens evolve separately in populations as a result of gene flow across the continents. Gaining popularity is a Middle Ground theory, where modern humans evolve in Africa, having a second Out-of-Africa event but upon encountering archaic groups in Eurasia, they interbreed to eventually hit fully modern Homo sapiens.[5]

The fossil evidence does suggest some intermediaries between Neanderthals and modern Homo sapiens which would support a Middle Ground hypothesis. The problem here is that there can be high variability within a species and it is difficult to determine lineage based on what they look like and where they are found.[5] This then leads to DNA analysis of remains which shows a clear difference in base pairs between Neanderthals and moderns, lending to the Replacement Model. Multiple problems arise with this theory, including using current modern human DNA to compare instead of Neanderthal contemporary Homo sapiens. When using ancient modern humans, the differences in DNA sequencing falls between that of current moderns and extinct Neanderthals which would support the Middle Ground.[5] There is also a problem in qualitatively analyzing the DNA variation, for there can be significantly more variation between two chimpanzees living in the same group than there is between modern Homo and Neanderthals. Artifact evidence could also go either way when discussing bone tools and the Châtelperronian tool industry. Either Neanderthals are becoming fully modern humans and these examples are showing the cultural evolution in conjunction with physical evolution supporting either the Middle Ground or Multiregional hypothesis, or as modern Homo sapiens are coming in contact with Neanderthals they are sharing knowledge and the Neanderthals[5] are learning from the moderns in order to begin developing more advanced lithic technology.

There is no definite and clear conclusion to this debate, the evidence can be swayed in either direction to support either model and only upon more research and data collection, particularly regarding the Neanderthal genome, can any answer be derived. Today, the Replacement Model is far favored over the Multiregional Model, and the Middle Ground is gaining momentum within the intellectual community.

Sites and Significant Fossils

Neander Valley, Germany

Neanderthal 1
This skull cap is the type specimen fossil that all other Neanderthal classifications are based upon, it is the holotype. The brow ridges jut out, leading to the largely horizontal forehead. The cranium is long and low, all features that came to be characteristic of Homo neanderthalensis.


Shanidar Cave, Iraq



Shanidar Cave is located in the Zagros Mountains of north-eastern Iraq. Ralph Solecki and his team excavated the relatively inaccessible cave between 1957 and 1961, discovering the first adult Neanderthal skeletons in Iraq. The site is best known for its evidence of ritualistic burial in pits lined with flowers and for evidence of compassion, having an adult specimen display trauma related injuries and still living to an old age presumably due to help from others.


La Ferrassie, France

This cave site, located in the Les Eyzies region of the Periogord Dordogne Valley of France, is interpreted as having eight individual intentional burials of two adult and six Neanderthal children. These burials date to approximately 35,000 years ago. The specimen La Ferrassie I is one of the most complete Neanderthal skeletons ever discovered. [9]

La Chapelle-aux-Saints, France

This site in France is where the "Old Man" of La Chapelle was discovered and analyzed by Marcellin Boule. Shows much evidence of burial with very clear grave pits. Also excavated in 1908 by Abbots Amédée, Jean Bouyssonie and Louis Bardon.

Spy, Belgium

References

  1. Also spelled Neandertal. The original German spelling includes an h but is pronounced as if no h is present. Kenneth L. Feder The Past in Perspective: An Introduction to Human Prehistory 4th ed. McGraw-Hill, 2007.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 Stringer, Christopher, and Clive Gamble. In Search of the Neanderthals: Solving the Puzzle of Human Origins. New York: Thames and Hudson Ltd., 1993.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Tattersall, Ian. The Last Neanderthal. New York: Macmillan, 1995.
  4. 4.0 4.1 4.2 Hoffecker, John F. A Prehistory of the North: Human Settlement of the Higher Latitudes. New Brunswick: Rutgers UP, 2005.
  5. 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 5.22 5.23 Kenneth L. Feder The Past in Perspective: An Introduction to Human Prehistory 4th ed. McGraw-Hill, 2007.
  6. "Dental Enamel Hypoplasia." Online Medical Dictionary. 29 Apr. 2008 <http://cancerweb.ncl.ac.uk/cgi-bin/omd?dental+enamel+hypoplasia>.
  7. Pettitt, P. B. (2000), "Neanderthal Lifecycles: Developmental and Social Phases in the Lives of the Last Archaics", World Archaeology 31: 351-366, DOI:10.1080/00438240009696926
  8. 8.0 8.1 Gargett, Robert H. "Grave Shortcomings: the Evidence for Neandertal Burial [and Comments and Reply]." Current Anthropology 2nd ser. 30 (1989): 157-190. JSTOR. University of Colorado At Boulder, Boulder CO. 28 Apr. 2008. Keyword: Shanidar. http://www.jstor.org/stable/2743544
  9. Hirst, K. Kris. ""La Ferrassie Cave (France)"" About.Com: Archaeology. 2008. Dictionary of Archaeology. 28 Apr. 2008 <http://archaeology.about.com/od/fterms/g/laferrassie.htm>.