Assimilation or replacement - astudy about
Neanderthals and modern humans

von: Christian Schäfer

Contents

1. Introduction p.3

2. Description and comparison of the two main characters p.3

a) Morphology  p.3
b) Cultural abilities p.4
c) Dispearsal areas p.4
d) Time span of existence  p.5

3. Who was the last common ancestor of Neanderthals and modern humans  and where did he live?  p.5

a) Genetic evidene p.5
b) Fossil record  p.5

4. Description of the main issue  p.6

a) Presentation of the four hypothesis concerning the transition from H. ergaster/erectus to Homo sapiens p.6
b) Integration of “assimilation” and “replacement” into these models p.6

5. Molecular/genetic research  p.7

a) mtDNA comparison of Neanderthal fossils, modern human remains and current modern humans p.7

6. Archaeological and palaeontological research p.8

a) Comparison of the morphology of skeletal remains of different ages and parts of the world p.8
b) Comparison of the cultural remains of different ages and parts of the world  p.9

7. Simulation studies  p.10

a) What are they based on?  p.10
b) What are the results?  p.11

8. Conclusions p.12

9. References  p.13

1. Introduction

The Neanderthals lived in Europe and the Near East for at least 250,000 years and they outdared several climate changes. They were capable of surviving in a harsh, cold environment and were well adapted to it – cultural and morphological. Thus, the Neanderthals have been proven to be a successful human kind. But why then did they disappear so quickly and without a trace just between 40,000 and 28,000 yr BP (= years before present) [8]?
One possible answer is that modern humans starting to invade the Near East and Europe out of Africa 45,000 to 40,000 yr BP have outcompeted them, due to higher cultural and mental abilities, using the resources in a more efficient way than the Neanderthals. But is this really true? Have modern humans really had higher abilities? Did they admix with the local Neanderthal populations, integrating the native genes in their gene pool? Or did modern humans not interbreed with them?
And – the big question: were Neanderthals and anatomically modern humans distinct species or just local variants of the same species?
To bring more light into this scenario, these questions will be answered in the following chapters using genetic, morphological and simulation-data that has been brought up by several researchers over the last years.
Answering these fundamental questions also lies in the range of basic needs of human mind: we all want to know where we come from, who was our ancestor and who was it not. To realize which strange ways evolution sometimes takes and to determine what really happened is for sure an exciting thing, and that is exactly what researchers do when they trace human evolution back to the point when Neanderthals and modern humans met in Europe during the last ice age. Only one of them should survive this meeting, and to determine why and how this happened I will start with the description and comparison of the two main characters.

2. Description and comparison of the two main characters

a) Morphology:

A typical Neanderthal man was of short figure - around 160 or 165 cm. There was quite a strong sexual dimorphism as Neanderthal women were around 10 % smaller than men.
In particular the legs were very short compared to the upper part of the body which also showed an enlarged rib cage. This is due to large lungs that made a Neanderthal breathe efficiently. Neanderthals had heavy bones that were very thick and thus quite resistant to mechanical disturbance. They had short thick fingers and arms. Also, the cranium was robust showing thick prominent brow ridges and a flat shape, in particular a low forehead. The face was projecting with a big nose and chinless. The back of the skull showed an occipital bun. Over all, the cranial capacity was very large – the average is around 1500 ccm, but an individual with even around 1800 ccm has been found. From the bone morphology can be deducted that Neanderthals were very muscular and thus weighed a lot compared to their size (around 75 kg at 165 cm). Thus, the typical morphology of a Neanderthal shows a strong adaptation to the rough cold climate in Europe during the ice ages and can be characterized as an extreme sprinter [3], [5].
A typical anatomically modern human is and was taller – with an average of 180 cm today – and shows less sexual dimorphisms as modern human women are around 7% smaller than men. He has quite long legs and a small rib cage. He possesses light, more gracile bones and longer, thinner fingers and arms. The cranium is more gracile in general and has strongly reduced brow ridges. The skull shows a high forehead and is more round in general showing no occipital bun. The face is not projecting with a smaller nose and shorter jaws. It shows a chin. The cranial capacity is large, but not as large as the Neanderthal one: the average is around 1400 ccm. The body is not very muscular and – at least for primitive people – the weight not that great compared to the size. Anatomically modern humans are thus not well-adapted to cold climates but rather to temperate or subtropical climates and can be characterized as generalists or long-distance runners [3], [5].

b) Cultural abilities:

The Neanderthals were no primitive, culture-less people. In fact, they probably had a language indicated by a fossil hyoid showing strong similarity to ours. Especially the hole for the nerves controlling the tongue is as big as ours suggesting that the tongue’s flexibility was very high. Anatomic studies show that the larynx was built the same way as ours. All these features would make no sense unless it gave the Neanderthals the advantage that language and effective communication offers. This advantage far outweighs any disadvantages of spending resources on developing such an anatomy and the added danger of choking. Also, Neanderthals had a highly developed weapon culture, ranging from hunting spears with stone tips to scrapers and hand-axes. Neanderthals were able to use fire and wore clothes that they made from the skin and fur of their prey. They lived in caves and sometimes built small temporary housings. They had a strong social company which is indicated by fossils that show heavy but healed bone-injuries and old people without teeth that were fed by younger group members. Neanderthals were also used to spiritual thinking as they buried their dead in special places with elaborate burial objects like flowers and decorated tools. Thus, they were a folk with both culture and tradition [12].
Anatomically modern humans had all the abilities mentioned above but they had some additional cultural achievements. These were in particular the development of abstract art (cave paintings, music instruments, pearl chains out of shells and the abundant use of red ochre) and better hunting weapon and tool technologies (complex bone technology and multiple-component missile heads). Good examples are the approximately 30,000 year old ivory flute from Germany, the perforated snail shells from Blombos Cave in South Africa which are about 77,000 year old or the cave paintings from Chauvet, France, that are about 30,000 years old [8], [13]. All these things show that perhaps they had a spiritual advantage over the native Neanderthals. Thus, anatomically modern humans show an advanced status of cultural level compared to Neanderthals.
This difference perhaps stems from the better conditions that anatomically modern humans found in the subtropical Africa whereas Neanderthals, although perhaps capable of these things, just didn’t have the adequate environment to realize them. Another possible kind of view is that anatomically modern humans had a more flexible mind giving them these cultural advantages, maybe because they were not extremely adapted to a harsh environment and thus not “programmed” to just survive like the Neanderthals. Today we cannot distinguish whether the first or the latter conclusion is right because we unfortunately cannot test a Neanderthal’s ability to perform art. Additionally, some artefacts that were found and are associated with art cannot clearly be assigned to modern humans and might be due to Neanderthal art [1]. Also, there is evidence that Neanderthals started manufacturing art when they started to get in contact with anatomically modern humans [8]. Whether they just copied it without understanding it or whether they got the spark and started doing it themselves is not distinguishable today.

c) Dispearsal areas:

The Neanderthals occupied primarily South-Western, Middle and South-Eastern Europe, but fossil finds indicate that they were also present in the Near East [8].
The first fossils of anatomically modern humans were found in South and East Africa, but they soon spread over North Africa to the Near East invading Europe and Asia. Later on, Australia and the American continent were colonized by them. During this population movement process all other archaic human populations like the Neanderthals or Homo erectus disappeared all over the world [8].

d) Time span of existence

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