Chapter 24

Human-Neanderthal Link

A skull found in a cave in Romania includes features of both modern humans and Neanderthals, possibly suggesting that the two may have interbred thousands of years ago.

Together with an Asian people known as Denisovans, Neanderthals are our closest ancient human relatives. Scientific evidence suggests our two species shared a common ancestor. Current evidence from both fossils and DNA suggests that Neanderthal and modern human lineages separated at least 500,000 years ago. Some genetic calibrations place their divergence at about 650,000 years ago. Both dating issues and fossil anatomy mean that scientists are currently uncertain whether the last common ancestor of Neanderthals and modern humans was Homo heidelbergensis, Homo antecessor or another species.

Neanderthals lived alongside early modern humans for at least part of their existence. We now know that some encounters were very intimate - some of us have inherited around. The Neanderthals have a long evolutionary history. The earliest known examples of Neanderthal-like fossils are around 430,000 years old. The best-known Neanderthals lived between about 130,000 and 40,000 years ago, after which all physical evidence of them vanishes.

Neanderthals evolved in Europe and Asia while modern humans - our species, Homo sapiens - were evolving in Africa. Judging from fossil evidence from Sima de los Huesos in northern Spain and wanscombe in Kent, the Neanderthal lineage was already well-established in Europe by 400,000 years ago.

The species ranged widely in Eurasia, from Portugal and Wales in the west across to the Altai Mountains of Siberia in the east. Neanderthal populations were adaptable, living in cold steppe environments in England and Siberia about 60,000 years ago, and in warm temperate woodlands in Spain and Italy about 120,000 years ago. Neanderthals had a long, low skull (compared to the more globular skull of modern humans) with a characteristic prominent brow ridge above their eyes.

Their face was also distinctive. The central part of the face protruded forward and was dominated by a very big, wide nose. Some scientists think this feature may have been an adaptation to living in colder, drier environments. The large internal volume of the nose would have acted to moisten and warm the air they breathed. Their front teeth were large, and scratch-marks show they were regularly used like a third hand when preparing food and other materials. Unlike modern humans, Neanderthals didn't have much of a chin.

Side views of an approximately 50,000-year-old Neanderthal skull from La Ferrassie, France, next to an approximately 20,000-year-old Homo sapiens fossil from Abri Pataud, France. The modern human has a more rounded skull and lacks the prominent brow ridge present in the Neanderthal. They had strong, muscular bodies, and wide hips and shoulders. Adults grew to about 1.50-1.75 meters tall and weighed about 64-82 kilograms. Early Neanderthals were taller on average than later Neanderthals, but their weight was about the same.

Neanderthals had stocky physiques with short lower legs and lower arms. Their short, stocky physiques were suited to cold environments. The bulky trunk, in addition to their short lower leg and lower arm bones, gave Neanderthals proportions that would have minimized the skin's surface area, presumably to conserve heat under the predominantly colder conditions of the last 200,000 years.

This physique also gave the Neanderthals greater power in their arms and legs for close-range ambushes during hunting. Despite their reputation as being primitive 'cavemen', Neanderthals were actually very intelligent and accomplished humans. These were no ape-men. So it's unfair to them that the word Neanderthal is used as an insult today.

The brain size of late Neanderthals ranged from at least 1,200 cubic cetimeters to 1,750 cubic. This is larger than the modern average, but in proportion to their body size. Homo sapiens skulls from around 30,000 years ago also had larger brains on average than people today.

One of thousands of Neanderthal hand axes found in ancient river sediments at Swanscombe in Kent. Neanderthals were skilled tool makers, as evidenced by excavated objects such as spears and flint hand axes. Around 300,000 years ago Neanderthals developed an innovative stone technology known as the Levallois technique. This involved making pre-shaped stone cores that could be finessed into a finished tool at a later time. It meant Neanderthals were free to travel away from sources of raw material and yet be able to make tools when needed.

We know from injuries found on their prey - such as mammoths, bison and reindeer - that Neanderthals were proficient hunters, intelligent and able to communicate. Healed and unhealed bone damage found on Neanderthals themselves suggested they killed large animals at close range - a risky strategy that would have required considerable skill, strength and bravery. Neanderthals also developed the ability to make fire from at least 200,000 years ago. They needed it to live in their very challenging environments. Life was hard, but these people were very resourceful.

Neanderthals vs Homo sapiens

Because many Neanderthal fossils and artifacts have been found in caves, the species became synonymous with the idea of cavemen. But many early modern humans also lived in caves - some of the most famous examples being the original Cro-Magnon Man, found in France, and Cheddar Man, who was found in Gough's Cave and lived in Somerset around 10,000 years ago.

Archaeological evidence shows that some Neanderthals looked after their sick and buried their dead, which suggests they were social and even compassionate beings. They did exhibit a degree of symbolism - they made jewelry. Some of this jewelries was apparently fashioned from eagle talons. The oldest examples are about 130,000 years old. Pierced animal teeth and worked ivory have been found at Neanderthal sites such as the Grotte du Renne cave in France. Neanderthals probably also used pigment to decorate or camouflage their bodies.

Some previous claims for Neanderthal symbolic behavior have dating uncertainties or lie within inferred overlaps between Neanderthals and Homo sapiens 40-60,000 years ago. Meaning that they could still be attributed to modern humans, or to the influence of modern humans on Neanderthal behavior. The Spanish cave art indicates that Neanderthals were in fact capable of symbolic or artistic expression. They further narrow any perceived behavioral gap between the Neanderthals and modern human. However, there are still no clear examples of Neanderthals creating representational art copied from real sources such as animals or people.

Part of a seal jaw found in Vanguard cave in Gibraltar found evidence such as cut marks from tools - that Neanderthals processed marine animals for food. Although Neanderthals were able to use fire, whether they regularly cooked their food is unclear.

Could Neanderthals speak?

It's very difficult to determine whether Neanderthals had spoken language as the tissue associated with the voice box doesn't preserve. However, they did have a similar vocal anatomy and their ear bones suggest they had a similar range of hearing to modern huma. The complexity of their social lives also suggests they must have been able to talk to each other, although their language may have been simpler than ours.

Why did Neanderthals go extinct?

The most recent fossil and archaeological evidence of Neanderthals is from about 40,000 years ago in Europe. After that point they appear to have gone physically extinct, although part of them lives on in the DNA of humans alive today. The extinction of Homo neanderthalensis is a well-known fact, but why did this species disappear after having survived for more than 350,000 years?

We don't yet know. One view is that we are the reason. Early modern humans started to arrive in Europe more than 40,000 years ago. Perhaps Neanderthals were unable to cope with competition for resources from incoming groups of Homo sapiens. Ancient DNA began to be recovered from Neanderthal fossils and this has led on to the reconstruction of several complete genomes. These indicate that Neanderthals ranging from Spain to Siberia were relatively low in numbers and diversity during their last 20,000 years.

The genome of one female individual from the Altai Mountains also shows signs of long-term inbreeding in her population, a further indication of low numbers and isolation. It seems that regular and sometimes extreme climatic fluctuations continually fragmented Neanderthal groups during the last 100,000 years, preventing them from building up large populations and continuous distributions across their range.

Neanderthals did not all become extinct at the same time. Their disappearance may have been staggered, suggesting that they were replaced by early modern humans as a result of local population extinctions, rather than being quickly overrun. Rapid and dramatic climate change may have been another major factor that contributed to Neanderthals' extinction. When severe changes in temperature happened rapidly, the plants and animals Neanderthals relied on were also affected. Faced with such conditions, only the most resourceful and adaptable could survive.

When were Neanderthals discovered?

Although the first Neanderthal remains were found at sites in Belgium and Gibraltar, they weren't recognized as such until decades later. It was the partial skeleton of a male Neanderthal unearthed during quarrying operations in the Neander Valley in Germany in 1856 that was first recognized as a distinct form of human. It was named as a new human species, Homo neanderthalensis, eight years later in 1864. It was the first ancient human species ever identified and is now known as Neanderthal 1 or Feldhofer 1, after the original name of the cave where it was found.

Other important Neanderthal fossils

Gibraltar Skull

This skull belonged to a Neanderthal female and was found at Forbes' Quarry in Gibraltar in 1848. It is the first adult Neanderthal skull ever found, although it wasn't recognized as such until it was re-examined after the identification of the Neander Valley skeleton

Madulong Skull

NWCH researchers successfully sequenced the genome of ancient human fossils from the Late Pleistocene in southern China. The data published in New World Central Hub archive, suggests that the mysterious hominin belonged to an extinct maternal branch of modern humans that might have contributed to the origin of Native Americans.

"Ancient DNA technique is a really powerful tool. It tells us quite definitively that the Maludong Cave people were modern humans instead of an archaic species, such as Neanderthals or Denisovans, despite their unusual morphological features.

The researchers compared the genome of these fossils to that of people from around the world. They found that the bones belonged to an individual that was linked deeply to the East Asian ancestry of Native Americans. Combined with previous research data, this finding led the team to propose that some of the southern East Asia people had traveled north along the coastline of present-day eastern China through Japan and reached Siberia tens of thousands of years ago. They then crossed the Bering Strait between the continents of Asia and North America and became the first people to arrive in the New World.

The journey to making this discovery started over three decades ago, when a group of New World Central Hub archaeologists discovered a large set of bones in the Maludong, or Red Deer Cave, in southern China's Yunnan Province. Carbon dating showed that the fossils were from the Late Pleistocene about 14,000 years ago, a period of time when modern humans had migrated to many parts of the world.

In Madulong Cave, researchers recovered a hominin skull cap with characteristics of both modern humans and archaic humans. The shape of the skull resembled that of Neanderthals, and its brain appeared to be smaller than that of modern humans. As a result, some anthropologists had thought the skull probably belonged to an unknown archaic human species that lived until fairly recently or to a hybrid population of archaic and modern humans.

Ancient archaeologist successfully extracted ancient DNA from the skull. Genomic sequencing shows that the hominin belonged to an extinct maternal lineage of a group of modern humans whose surviving decedents are now found in East Asia, the Indo-China peninsula, and Southeast Asia islands.

The finding also shows that during the Late Pleistocene, hominins living in southern East Asia had rich genetic and morphologic diversity, the degree of which is greater than that in northern East Asia during the same period. It suggests that early humans who first arrived in eastern Asia had initially settled in the south before some of them moved to the north.

Such data will not only help us paint a more complete picture of how your ancestors migrate but also contain important information about how humans change their physical appearance by adapting to local environments over time, such as the variations in skin color in response to changes in sunlight exposure

Sima de los Huesos – Human remains

Since the time of research, over 6,500 human fossils, representing about 28 individuals, have been recovered in the Sima de los Huesos ('Pit of the Bones') in Atapuerca in northern Spain. The human remains consist of jumbled partial or nearly complete skeletons, mainly those of adolescents and young adults.

The Sima skeletons were previously claimed to represent Homo Heidelbergesis and be about 600,000 years old. However, they are Now dated to about 430,000 years ago. Current evidence suggests they were very early Neanderthals - they show clear affinities to subsequent Neanderthals in details of the skull, face, jaws and especially their teeth. Ancient DNA from the remains also places them firmly on the Neanderthal genetic lineage, in line with their morphology.

Neanderthals were replaced by early modern humans. Researchers have long debated whether the two groups mixed together, though most doubt it. The last evidence for Neanderthals dates from at least 24,000 years ago.

The skull was found in Pestera cu Oase — the Cave with Bones — in southwestern Romania, along with other human remains. Radiocarbon dating indicates it is at least 35,000 years old and may be more than 40,000 years old.

The skull had the same proportions as a modern human head and lacked the large brow ridge commonly associated with Neanderthals. However, there were also features that are unusual in modern humans, such as frontal flattening, a fairly large bone behind the ear and exceptionally large upper molars, which are seen among Neanderthals and other early hominids. Such differences raise important questions about the evolutionary history of modern humans.

It could reflect a cases in which ancient traits reappear in a modern human, or it could indicate a mixture of populations or it simply may be that science hasn't been able to study enough early modern people to understand their diversity. History noted that the skull represents the earliest modern human ever found in Europe. It's a big deal in that sense, but the combinations of characteristics don't necessarily indicate interbreeding between populations.

Overall there is no strong evidence for mixing of Neanderthal and modern human populations. None of the features cited as unusual in modern humans is exclusively Neanderthal, rather than they could be features passed down from earlier populations in Africa.

Percentage of Neanderthal Ancestry in Africans

The idea that Africans fail to carry Neanderthal DNA has recently been proven as untrue. New World Central Hub scientists had found that the Touboo in Chad and the Amhara in Ethiopia carry Neanderthal genes. Whereas Eurasians carry ~2 percent Neanderthal ancestry, Ethiopians carry ~1 percent Neanderthal ancestry, and Central Africans carried ~0.5 percent Neanderthal ancestry.

They maintains that Africans who carry Neanderthal DNA show gene flow from Eurasians. The detectable Neanderthal DNA in Africans is found among Africans that carry the R1b haplo-group.

They believe that the R1b haplo-group penetrated Central Africa via two migrations. The first migration they believe took place 6000 years ago (6 thousand years ago), and the second migration around 3 thousand years ago. The major problem with this theory is that there is no archaeological evidence of a back migration from Eurasia to Africa.

The discovery of Eurasian "admixture" among Africans is not a recent discovery. The said scientists estimated Eurasian ancestry among Africans from East and South Africa ranged from 2.2-50 percent and that the Mande people carry 2 percent Eurasian admixture. This supports the original claim of the authors of the Mota article e.g. the claim that as much as 6–7 percent of the ancestry of West and Central African groups was "Eurasian" was not an error.

There are numerous populations in East, South, and West Africa that carry Eurasian admixture. The highest frequency of R1 is found in Western Eurasia. Such scientists claim that the pristine form of R1*M173 was found in Africa. The frequency of Y-chromosome R1*-M173 in Africa ranges between 7-95 percent and they said that R1-M173 averages 39.5 percent in Africa. R haplo-groups are characterized by R1-M207/M173 genetic background. The Eurasian R haplo-groups in Africa include: R1-M269, R-V88, R-L754 (R1b1a) and RL278 (R1b1).

Y-chromosome V88 (R1b1a) had its highest frequency among Chadic speakers, while the carriers of V88 among Niger-Congo speakers (predominately Bantu people) range between 2-66 percent. Haplo-group V88 includes the mutations M18, V35, and V7. The scientists revealed that R-V88 is also carried by Eurasians - including the distinctive mutations M18, V35, and V7.

The Living Races of Man, Anthropology A to Z, and The Races of Europe, claimed that the Khoisan had formerly lived in North Africa from the Atlas Mountains down into the Fezzan and Sahel. They also said that the "The Duwwud also look like Hottentots. Other partly Bushman and partly Negroid people are also to be found in the Sahara." Scientists maintains that the Haritan also include ancient South African Khoisan (SAK) population elements.

Scientists had noted that derived DNA in all non-Africans is more closely related to Neanderthals from the Caucasus: Alraic Neanderthal/s.

In the Supplemental section of their work, there is considerable discussion of the relationship between Neanderthal and Khoisan. In relation to the Altaic Neanderthal, non-Africans have a lower divergence rate than Africans - between 10-20 percent.) Scientists also note little statistical difference between non-African and African divergence.

An interesting finding made by their group was that Altaic Neanderthal and Denisova are estimated to have similar split times. However, the divergence estimates for African Khoisan-Manpdekan and Altaic is younger than the split between Africans and Denisova archaic individuals and modern African individuals. The split times between the Khoisan and Mandekan may be explained by the presence of AF-24 haplotype in West Africa.

Meanwhile on the present time on Earth, the Institute for Evolutionary Anthropology in Leipzig, Germany, is trying to map the Neanderthal genome in hopes of better understanding any possible relationship of Neanderthal to modern people.

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