20 Homo sapiens

Dr. Shailendra Kumar Mishra

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Contents of This Unit

1. Introduction

2. Homo sapiens

3. Approaches to understand modern human origin

(a) Complete replacement model

(b) Partial replacement model

(c) Regional continuity/multiregional model

(d) A critical appraisal of the models of modern human evolution

4.Major fossil discoveries of modern human

(i) Africa

(ii) Asia

(iii) Europe

(iv) Australia

5. Technology and art

(i) Upper Paleolithic technology

(ii) Upper Paleolithic arts

6. Conclusions

7. Summary points

 

 

Learning Objectives:

  1. To develop an understanding about characteristic features of H. sapiens.
  2. To describe various fossil finds discovered from several places in Africa, Asia, Europe and Australia.
  3. To discuss various models of the evolution of modern human.
  4. To describe Paleolithic and artistic cultural traditions associated with H. sapiens.

Homo sapiens

 

INTRODUCTION

Over past few decades, scholars of several disciplines remained keen to understand emergence and evolution of biologically and behaviorally ‘modern’ human. New discoveries and new scientific techniques have changed the discourse about evolution of modern man. Sophisticated dating methods and molecular approaches have brought a paradigm shift in discoveries and interpretation on human evolution. Acknowledging abilities to exploit surrounding environment, emergence and existence of human particularly Homo sapiens remained central issue of debate in modern academic thoughts.

 

Discoveries of Homo erectus from several sites in different continents inculcated interest among scholars to trace missing links between Homo erectus and Homo sapiens. Interpretation of Petralona skull by Stringer, Howell and Melentis showed that size of brain case, difference in skull structure pertaining to enlarged brain size are distinguishing features from Homo erectus to Homo sapiens (Stringer et al., 1979). Several discoveries from Africa, Europe, Asia, Australia and New world have established antiquity of Homo sapiens fossils and associated tool technologies as well as arts.

 

HOMO SAPIENS: There is no general agreement about the definition of Homo sapiens. Certain biological and cultural characteristics are attributed to the species ‘sapiens’ which includes increased size of brain case, increased height of skull vault, smaller amount of constrictions or wasting behind the orbits, relatively lower position of ridges on skull for the attachment of neck muscles. Associated with this are cranial capacity of 900 to 2300 cc, rounded occiput, bent basicrania, maximum skull breadth higher on the skull, flatter face, well defined chin and smaller incisors as distinct feature of Homo sapiens. Postcranial features include straighter long bones with less articular surface for the attachment of muscles, bones are thinner than in Neanderthals, sockets of femurs are farther forwarded and less powerful grip, etc (Stein and Rowe, 2011).

 

Owing to changed climatic conditions during Pleistocene period Homo sapiens evolved and developed advance tool technology and associated art traditions. Upper Paleolithic period is mainly associated to early Homo sapiens. Several scholars believe that pictorial art originated with modern man. Although Neanderthal and modern people emerged almost together yet pictorial art developed not before 40,000 years ago. This suggests that pictorial art is a result of environmental changes and cultural exchange and not because of biological modifications. People before modern man might have other creative outlets which are a matter of investigation for present day palaeoanthropologists.

 

APPROACHES TO UNDERSTAND MODERN HUMAN ORIGIN

 

The dominant hypotheses to understand origin of modern human are:

(a)   Complete/total replacement model

(b)  Partial replacement model

(c)   Regional continuity model/multiregional evolution model

 

Complete/total replacement and regional continuity/multiregional models are two prominent however totally opposite views from each other. The third theory i.e. partial replacement model is a compromised view incorporating some aspects of both the models.

 

Complete/ Total Replacement Model: This model was proposed by British Anthropologists Christopher Stringer and Peter Andrews (1988). This hypothesis says that Homo sapiens have evolved in Africa around 200,000 years ago. It also proposes that anatomically modern human population emerged only in African continent and then fully modern human migrated to Asia and Europe i.e. transition from pre-modern to modern exclusively took place in Africa as a result of speciation process. Thus migrated Homo sapiens could not interbreed with non-African human populations in other continents. And populations belonging to genus Homo in other continents were different species such as Neanderthal was H. Neanderthalensis and so on. This explanation fit well with the proposition of complete replacement. Genetic techniques have changed the theories of human evolution. Genetic studies used numerous contemporary human populations as a data source to precisely determine and compare a wide variety of DNA sequence. They considered Y chromosome and mt-DNA differences particularly informative since neither is significantly recombined during sexual reproduction. It is noteworthy that Y chromosome follow paternal line of inheritance (from father to son) and mt-DNA follow maternal line of inheritance (from mother to daughter) without significant deviation. Accumulated data about populations worldwide have shown that African aborigines have far greater diversity than population elsewhere across the globe. Apart from genetic data on contemporary human populations, DNA samples were collected from more than a dozen of Neanderthal fossils. Further, researchers have recently sequenced the mt-DNA of nine ancient fully modern H. sapiens from sites in Italy, France, Czech Republic and Russia. Preliminary results from these studies also support complete replacement model (Caramelli et al., 2003). However, more analysis is needed to confirm the results as several questions have been raised against the findings of these studies.

 

  Partial Replacement Model: In fact majority of the scholars are of the view that modern human evolved in Africa and that when their population swelled up they migrated to Asia, Europe and other parts of the globe. But, unlike complete replacement model, supporters of partial replacement hypothesis argue that some interbreeding has taken place between African emigrants and resident pre-modern populations of the regions. Thus, they opine that no speciation has occurred and resident pre-modern populations were members of species H. sapiens. Günter Bräuer, John Relethford, and Fred Smith are main proponents of this model (Relethford, 2001).

 

   Regional Continuity Model/Multiregional Evolution Model: Proponents of this model suggest that major sections of local indigenous populations in Africa, Europe and Asia continued their indigenous evolutionary development from Middle Pleistocene form to modern human (Wolpoff et al., 2001). A general and broad anatomical and genetic similarity among different population groups across the globe is hard to be explained by this model. To counter this argument multiregional model theory says that gene flow was possible during Pleistocene period and therefore anatomical and genetic similarities among the population are quite natural. The hypothesis further argues that because of natural selection and gene flow, evolution of several population groups in a particular region was not totally independent. The process of mixing prevented speciation helped evolution of human as only one species i.e. Homo sapiens however it remained quite polytypic (Smith et al., 1989). The model says that all hominins following H. erectus are classified as a single species H. sapiens. In spite of a strong view on regional evolution of modern human the model also accepts influence of African emigrants throughout the world which can easily be detected.

 

  A critical appraisal of the models of modern human evolution: Despite over popularization and dramatic representation of their views proponents of the theories of evolution of modern human are now conversing to a consensus view. Recent palaeoanthropological discoveries, data from sequenced ancient DNA and sequenced data from contemporary human populations suggest that a strong multiregional model is inadequate to explain evolution of modern human. The proponents of multiregional theory argue that anatomically modern human in Asia, Europe and other regions has evolved from their pre-modern ancestors with only limited interbreeding with African emigrants. It is difficult to defend their views with available evidence across the globe. As of now there is hardly any evidence to oppose complete replacement model but the finding of the recent discoveries suggest about the potential for at least some amount of interbreeding of African emigrants with indigenous populations elsewhere. Therefore both complete replacement and multiregional model are going to be insufficient to explain the phenomenon of evolution of modern human.

 

MAJOR FOSSIL DISCOVERIES OF MODERN HUMAN

AFRICA: Fossils discovered from Africa are the oldest. Fossils from Omo Kibish in Ethiopia are dated about 195,000 years old as determined by radiometric dating techniques. Marked differences in morphological characteristics of two fossils (Omo 1 and Omo 2) discovered from this site. Fossil Omo 1 is definitely modern morphological characteristics as it has well defined chin whereas Omo 2 has robust i.e. less modern morphology.

 

Year 2003 is benchmark in the history of modern human fossils in Africa when the discovery of Herto fossil (one adult skull, one child skull and another incomplete skull) from Middle Awash region of Ethiopia took place. These are best dated hominin fossils from this time period (White et al., 2003). Using radiometric dating these fossils were estimated 160,000 to 154,000 years old. The preservation quality and morphology of fossils clearly demonstrate their close relationship to modern humans. The cranial capacity of these fossils is 1450 cc i.e. very similar to contemporary H. sapien populations. They were named Homo sapiens idaltu to distinguish them from H. sapiens sapiens. In Afer language ‘idaltu’ means elder.

 

The fossil finds from Klasies River mouth and Border Cave in South Africa bears many characteristics similar to modern humans.

 

ASIA: The sites yielded fossils of modern human populations which are mainly located in Israel, China and Indonesia. In Israel, anatomically modern human fossils, almost of Neanderthal time, were discovered from Jebel Qafzeh and Tabūn (Grun and Stringer, 1991). The fossils were dated as 120,000 to 92,000 years ago. Most of the fossil remains showed modern characteristics however few representative fossils have pre-modern characteristics. Such early dates of the fossils raises question against theory of complete replacement and also supports the view that modern human and Neanderthals were together.

 

Significant modern human fossil sites in China are Zhoukoudian and Tianyuan caves. The sites belong to Late Pleistocene period with dates less than 40,000 years ago. Upper cave of Zhoukoudian yielded three skulls with cultural materials dated about 27,000 years old. Forward jutting zygomatic arch and shovel shaped incisors similar to modern Asian populations are important evolutionary characteristics present in one of skull. Near to Zhoukoudian another cave named Tianyuan has yielded skull, teeth and several postcranial bones (Shang et al., 2007). The antiquity of fossil finds was ascertained around 40,000 years old. The postcranial skeleton shows mostly modern characteristics and few pre-modern characteristics as well. Experts have noted that the fossils were found to have African origin however some amount of inbreeding with resident indigenous populations cannot be ruled out.

 

The other important site is Niah cave in Borneo island of Indonesia from where skull of an adult female was recovered. The radiocarbon dating has estimated the age of fossil to be about 41,000 years old. The skull lacks brow ridges, forehead is high and the back of the head is rounded. The features of Niah skull resemble modern populations of New Guinea. It was also concluded by few researchers that populations contemporary to Niah had perhaps the first people to populate Australia.

 

EUROPE: Earliest discoveries about H. sapien fossils are made from sites in Romania, Czech Republic, France, etc. Cranial remains of three individuals were recovered from Oase Cave in Romania. Despite being quite robust, cranium has a clear chin and a canine fossa (Trinkaus et al., 2003) which is similar to modern specimens. Several crania recovered from Mladeč in Czech Republic exhibit variation among them. The average features are intermediary forms between Neanderthal and modern man (Trinkaus et al., 2005).

 

Western Europe particularly southern France has been treasure trove of hominin fossils. Palaeoanthropological research in this region has spanned more than 150 years. These fossils remained major evidence for the theories on modern human evolution as material from other regions of the world were not available for comparisons. Discoveries from other parts of the globe and new dating technologies have changed the discourse of human evolution since the last few decades. The best yielding site of modern human fossils is Cro-Magnon, a rock shelter in southwestern France. From this site several partial skeletons were recovered that are believed to be prototypes of H. sapiens. A section of scholars believed that Cro-Magnon people were light skinned, beardless, upright-walking individuals who replaced Neanderthals from Europe. Cro-Magnons generally are characterized by broad and small faces with high foreheads and prominent chins and their cranial capacity is 1590 cc. With the help of postcranial remains their height was estimated to be 163 to 183 cm, however their skin colour, amount of body hair is a mere guess work.

 

AUSTRALIA: The earliest fossils remains discovered so far come from Lake Mungo in southeastern Australia. The fossils suggest that population in the region had modern anatomical features. Another important site in Australia is Kow Swamp. The fossils bear several archaic features however it’s postcranial resembles that of Austalian aborigins (Hudjashou, 2007). It is believed that human’s migrated to Australia about 50,000 years ago and populated this continent.

 

 

TECHNOLOGY AND ART

The period of modern human evolution is essentially associated with Pleistocene environment which remained crucial in evolution of technology and art of this population. This Upper Paleolithic culture was distributed in Europe, Asia and Africa. The environment was changing and it helped in emergence of Tundra in Europe. Vegetation supported growth of large herds of animals. Therefore cooperative group hunting evolved during this period unlike individualistic hunting. The major animals for hunting were reindeer, horse, bison, fish and so on. It seems that man might have altered the fauna of the region by hunting and by use of fire (Jurmain et al., 2011).

 

Upper Paleolithic Technology: The Upper Paleolithic is generally characterized by stone blades which were very efficient tools. Blades are made over stone flakes. The sides of flakes are roughly parallel with sharp edges. The ratio of height to breadth is more than 2:1. Flakes to prepare blades were removed from carefully prepared cores (Stein and Rowe, 2011). Capability to make blades shows efficiency of man to use natural resources. With the blades an array of tools were prepared for specialized purposes unlike Lower Paleolithic period where handaxe was used as general tool. By adding simple tools in different ways complex tools were prepared. During Upper Paleolithic bones, antlers, horns and ivory were also used to prepare more efficient tools as these raw materials had many advantages over stones. Use of bone resulted into development of burin which had a point that withstands tough pressure. Compound projectile tools having different parts were the reason for the success of Upper Paleolithic Culture. In such tools, wooden’s hafts were used to mount blades and to provide extra force during hunting. Spear and harpoon were other important tools during Upper Paleolithic period. Eyed needle was another important tool which was made form bone or ivory and was perhaps used for stitching warm clothes (Jurmain et al., 2011).

 

   Upper Paleolithic Arts: During Upper Paleolithic Period variety of artistic methods and styles were developed. Evolution of paintings and engravings took place during this period, as a result, colourful, stylized, realistic and geometric arts were evolved. Modeling of clay as well as paintings and engravings on big surfaces such as cave wall to small objects such as antlers were done. Famous statue includes Venus figurine with pronounced buttock and breast which represents fertility or motherhood. These figurines were made on various materials (Stein and Rowe, 2011). Scholars have concluded that artistic works of Upper Paleolithic People were combination of events of daily life chores and expression of spirituality. The earliest artistic work of Upper Paleolithic was dated about 32000 years old. Upper Paleolithic arts were reported from France, Italy, Spain, etc. (Jurmain et al., 2011).

 

Tool making traditions is Upper Paleolithic mainly included Chatelperronean, Aurignatian, Gravettianas, Solutrean and Magdalenian. In Europe, archeological sites from France have yielded almost all five types of traditions of Upper Paleolithic period. Chatelperronean appeared about 32000 years ago and had a combination of industries. Aurignatian tradition was mainly associated with Cro-Magnon man. It came just after Chatelperronean. Around 28000 years ago people started making tools on bones and antlers and ivory. Gravettian is known for predominant use of bones as raw material for tool making. Solutrean is more sophisticated tradition compared to earlier ones. Magdalenian tradition was generally associated with Neanderthal man. Almost similar blade industries were reported from regions such as Middle East, India, Siberia other than European countries (Stein and Rowe, 2011).

 

CONCLUSION

To know about our own evolution always remained a hunch of palaeoanthropologists. Fossil discoveries and analytical research have established that antiquity of modern human goes back to 195,000 years in Africa. Fossil evidence suggests that human reached Asia around 100,000 years ago, about 50,000 years back in Europe and around 35,000 years back in Australia. From last few decades debates are going on about the date and location of the origin of behaviourally and anatomically modern human population. In general, two opposite models have been proposed i.e. complete replacement and regional continuity. A third view is a rapprochement between both the models i.e. partial replacement. Complete replacement model argues that modern human fully evolved in Africa and then migrated to other regions of the world and replaced population residing there such as Neanderthals in Europe. Regional continuity model says that indigenous ancestors of different regions of the world evolved into modern human such as Neanderthals which gave rise to European population. The proponents of partial replacement model suggest that African emigrants though replaced indigenous populations in various regions of the world however some amount of interbreeding also took place. Evolution of modern human is also associated with cultural evolution i.e. evolution of refined tool traditions and arts. Almost everywhere early fossils of modern human remained associated with Upper Paleolithic Culture. Blades and burins were the characteristic tools along with compound tools made by mounting basic tools on suitables haft. Such tools were efficient in cooperative hunting of the big animals abundant during that period. Cave arts, beautiful figurine, engravings, colorful, stylized and geometrical artistic works are important characteristics of Upper Paleolithic Period. With gradual evolution these cultural traditions reached their zenith i.e. civilization in later era.

 

SUMMARY POINTS

  • Research to trace evolutionary history of behaviorally and physically modern human started in Europe about hundred years back. Later it extended to other parts of the globe.
  • Fossils of early modern human were discovered from Africa, Europe, Asia, Australia and even in New World.
  • Based on fossil evidence and molecular data two schools of thought (complete replacement and regional continuity) were proposed to explain origin and peopling of modern human across the world. An intermediary model was also proposed by certain scholars.
  • Evolution of modern human is also associated with evolution of tool and artistic traditions. With few variations, evidence has been collected from different areas of the globe including cave arts to symbolic arts and figurines to statues.
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REFERENCES

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