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Out of Africa : How the Modern Human Populated the Planet
Korean Minjok Leadership Academy
Kang, Su Yeon
Term Paper, AP World History Class, December 2011
Table of Contents
II. Modern Human, Homo Sapiens
II.2 Homo sapiens and other human species
III. Research Method
IV. From Africa to Asia, Europe, Australia, and America
IV.1.1 Out of Africa Theory
IV.1.2 Dissemination of Modern Humans within Africa
IV.2.1 Out of Africa into Asia
IV.2.2 Dissemination within Asia
IV.2.2.1 Within South and Southeast Asia
IV.2.2.2 Within Central, North and East Asia
IV.4.1 From Asia to Europe
IV.4.2 Dissemination within Europe
IV.4.3 Homo sapiens and Homo neanderthalensis
IV.6 The Islands
Ever since Darwin undermined the long-believed doctrine of creation by publishing his Theory of Evolution, we humans have strived to find what we evolved from and where we came from with strong curiosity. With extensive search and scientific development, we could find traces of our ancestors through excavation and come up with several theories such as the Multiregional Evolution Theory, which claims that human species have evolved through a combination of adaptation within various regions of the world , and the Out of Africa theory, which insists modern humans arose from Africa between 200,000 years and 150,000 years ago and has spread to all over the world ever since.
This paper aims to explain origins of modern humans based on Out of Africa theory which is predominant in current academic world. Using scientific methods, excavated sources, and lots of researches, it will give accounts to how plausible of Out of Africa theory is, and introduce theories on how and when humans migrated from Africa to other continents. Some island countries not mentioned in the main chapters would be separately explained.
II. Modern Human, Homo sapiens
There have been many human species such as Australopithecus afarensis (which lived from about 4,000,000 to 1,000,000 years ago), Homo habilis (2,300,000 BP to 1,400,000 BP), Homo erectus (1,600,000 BP to 200,000 BP), Homo neanderthalensis, etc before Modern humans existed. However, modern humans referred in this paper are Homo sapiens, the only living species in the Homo Genus. Homo sapiens, which is supposed to have appeared 200,000 years ago in Africa, is subdivided into species such as Homo sapiens idaltu, Homo sapiens archaic, Homo sapiens sapiens, etc but these subspecies would not be mentioned any more in this paper because all of them have same roots in Africa, are closely linked to each other by heredity and have subtle differences.
In this paper, the definition of youth would be quite flexible. As a prince/ princess is considered not fully mature until they become
king/queen, youth would be defined as a period before the prince becomes king, or a princess becomes a queen, etc. However,
if the monarchs become king/queen in a too old age, youth would be defined as a period of life until 25 - 30.
II.2 Homo sapiens and Homo neanderthalensis
Until recent, the Neanderthal men who appeared 350,000 years ago had been classified as a subspecies of Homo sapiens, Homo sapiens neanderthalensis. They shared the same era and the same regions for a long time. However, through some recent studies showing lots of differences between the Neanderthal men and Homo sapiens, lots of disputes about the classification of the Neanderthals are taking place among scientists.  As there is no conclusive theory which clarify its categorization, this paper will follow the assumption that the Neanderthals were separate species from Homo sapiens. Accordingly, following discussions on human journey will differentiate the two species and mention differences between them.
III. Research Method
To find out the origin and the migration of modern human, scientists have used various scientific knowledge and technology. This chapter will explain several major scientific methods used to trace human journey.
First of all, genetic knowledge is one of the major tools for scientists who study paleoanthropology since it gives clues to how we are related to ancient hominids, where humans came from, and through which route they have spread to the world. Specifically, they use genetic information in mitochondrial DNA and Y chromosomes. While most of humans DNA exist in chromosomes in nucleus, there is also little amount of DNA which delivers energy made by mitochondria to its cell in mitochondria. Since it is located far from nucleus, genes in mitochondria are not restricted to natural selection. Therefore, mutations in DNA are accumulated faster in mitochondria than in nucleus and this makes mitochondrial DNA useful in constructing genetic genealogy. What¡¯s more, different from DNA in nucleus, mitochondrial DNA inherits the same form of its mother¡¯s DNA as it does not have recombination process with father¡¯s DNA. Geneticists can trace back maternal lines using this aspect of mitochondrial DNA. On the other hand, they can find paternal genetic genealogy through examining Y chromosomes which also does not recombine with another chromosome. Although it is possible to use DNA in nucleus, it is much more complicated method than using mitochondrial DNA and Y chromosomes. Geneticists can easily trace one¡¯s ancestry by examining mutations found in these DNA. In addition, they can collect lots of DNA samples since one can get his or her DNA samples without difficulty and pain by simply scratching the inside of his or her mouth.
Archaeological approach provides conclusive information since it deals with substantial matters such as fossils, bones, tools, etc. By measuring dates of those matters through radiocarbon dating, geological dating, or so, we can guess approximate dates when humans made such remains. However, there can be many errors and large error range caused by technological imperfection and mistakes in dating.
Geological data are also great sources to draw possible routes of human migrations. It gives information about geographical and climatic changes, which must have greatly influenced greatly to the journey of humans. For example, they show information about sea level change, change in degree of desertification, volcanic eruption, Ice Age, etc which must have been great issues for movements of humans thousands of years ago.
IV. From Africa to Asia, Europe, Australia, America, and to islands
IV.1.1 Out of Africa Theory
One of the first scholars who came up with Out of Africa theory was interestingly Charles Darwin in his book, The Descent of Man in 1871. He supposed that since gorillas and chimpanzees, which are species similar to humans, live in Africa, ancestors of human also may have come from Africa. However, his idea was lacking in evidence then as no fossils were excavated and scientific methods were not much developed. It was not until late 20th century when Out of Africa theory was supported with genetic evidence and excavated sources.
In 1967, Richard Leaky found the two skulls and various bones in Ethiopia¡¯s Omo River Valley. Named as Omo I, they were classified as Homo sapiens since they were very similar to modern human, though in more primitive forms. While they were originally dated to 130,000 ago, the recent reexamination has determined that they were from 195,000 years ago, which is the oldest date of modern human¡¯s fossil ever discovered. This discovery greatly raised the credibility of Out of Africa theory and specified the origin of modern humans as east Africa.
Many genetic analyses also support Out of Africa theory. In an article of magazine Nature in 1987, Rebecca Cann, Mark Stoneking, and Allan Wilson show the result of mitochondrial DNAs analyses of 147 people. From the result, they conclude that all mitochondrial DNAs stem from one woman supposed to have lived about 200,000 years ago in Africa, thereby calling her as Mitochondrial Eve. One can ask how scientists know she is from Africa; this conclusion arises from the fact that the most various and complicated lineage of Mitochondrial DNAs is found in Africa. Gene diversity in Africa is important evidence which shows Homo sapiens is originated from Africa. Even after their studies, analyses on mitochondrial DNAs of lots of people have been continuously added, all supporting African origins of people. For example, according to a study in 2007, Australian aborigines and European share same African Roots.
 Scientists took samples from modern Aborigines and Asian population, and traced their family tree through their mitochondrial DNA and Y chromosome DNA. And they found that Australians are all descended from humans who migrated from Africa to Asia between 50,000 and 70,000. This study undermined multiregional theory greatly. In addition, in 2008, magazine Nature put a paper about the most detailed analysis on genetic diversity so far. Geneticists analyzed genes from 29 groups of people from all over the world and concluded that Homo sapiens spread from East Africa.
IV.1.2 Dissemination of Modern Humans within Africa
Then, how and when Homo sapiens moved from East Africa and spread to the rest of Africa? It is hard to answer to these questions because lots of migrations must have taken place throughout long time and archaeological and genetic studies in Africa are limited to only politically and economically stabilized countries. Scientists, though, try to answer to these questions by studying mitochondrial DNAs and Y chromosomes. They classify people into haplogroups which share same mtDNA or Y chromosomes genotype and suppose that four groups, the first generation of mtDNA gene type ¡®L1¡¯ travelled south to the Cape of Good Hope, south west to the Congo Basin and west to the Ivory Coast from around 160,000 to 135,000. It is thought that later, haplogroup L0 originated from East Africa appeared around 100,000 and migrated. Even after that, several haplogroups such as L2, L3, M2, M60, M91, etc may have migrated within Africa at intervals.
IV.2.1 Out of Africa into Asia
Exactly when and how Homo sapiens first moved from Africa to Asia is still disputed. It is supposed that there are four possible routes out of Africa: across the Straits of Gibraltar, from Tunisia up through Sicily and Italy, across the mouth of the Red Sea, and through the Sahara and Sinai deserts.
 Except for the route crossing Sinai deserts(peninsula), all routes cross ocean. However, since there is no evidence that Homo sapiens directly crossed to Europe from North Africa and a genetic research indicates that all European moved from east to west, it is thought that Homo sapiens moved from East Africa to other regions and then went to Europe. There are two routes from east Africa: one through Sinai deserts, and the other across the Red Sea.
It seems that several ¡°attempts¡± of Homo sapiens out of Africa were made (though they did not actually intend to move out of Africa), as there are some remains of Homo sapiens in the route crossing Sinai Peninsula. While during most of Pleistocene Epoch (period from around 2,3 million years ago to 10,000 years ago) it might have been very difficult to cross the northern route crossing Saharan desert and Sinai desert due to severe cold and dryness, there were several interglacial periods when the climate became warm and deserts turned to grassland. It is possible to find fossils of Homo sapiens in one of those periods which is between 130,000 years ago and 120,000 years ago in Levant regions such as Skhul and Kafzeh in Israel which humans have to cross Sinai Peninsula. However, it is thought that the group did not go further into Asian regions and died out by 90,000 years due to a global-freeze up and desertification.
Though there are several theories which suggest multiple routes could have been taken to go out from Africa, recent genetic studies seem to strongly suggest that there was only a single large group which made exodus out of Africa and from which all non-African descended. According to mtDNA analysis, all non-African today are descendants of haplogroup L3 which migrated from East Africa in about 84,000 years ago. Haplogroup L3, then, was separated into three haplogroup M, haplogroup N, and haplogroup R to which most non-African people are applied. It is said that of all the lineages present in Africa only the female descendants of mtDNA haplogroup L3 are found outside Africa. If there were several migrations, then, there would more than one lineage found outside Africa.
If only one group of people moved out of Africa and spread to all over the world, then which route did they take? Stephen Oppenheimer claims that they would possibly go through the southern route crossing Bab-el-Mandeb Straits connecting the Red Sea and Aden Bay since it was opened all the time while the northern route was impenetrable during ice age.  He suggests that the sea level would have dropped around 85,000 years ago and the group could have passed the Red Sea.
However, some scientists propose that there were two migrations out of Africa, one across the Red Sea travelling along the coastal regions to India, represented by Haplogroup M and the other through the Sinai, some of whom went into Europe, represented by Haplogroup N. This claim tries to explain why Haplogroup N is predominant in Europe and Haplogroup M is absent in Europe. But, the absence of Haplogroup M in Europe can be explained by a population bottleneck which could have made a small European population that initially expressed both Haplogroup M and N lose Haplogroup M through random genetic drift. 
In 2011, a study which can overturn all previous theories was presented in Science magazine. In Jebel Faya, United Arab Emirates, tools made by a group of hominids in 125,000 years ago were found. It was the period when the Sahara desert was savanna with plentiful water, and from this, the researchers suggest that these toolmakers could have crossed from Africa and spread to Europe, Asia, and Australia. If their claim is right, the date is 50,000 years earlier than the period which has been widely believed.
As can be seen above, there seem to be no real answers in which we can fully give credit to for now. Homo sapiens migration from Africa to Asia is still being actively studied and perhaps, further archaeological genetic research will be able to give satisfying answers to this topic.
IV.2.2 Dissemination within Asia
IV.2.2.1 Within South and Southeast Asia
About 74,000 years, there was a great volcanic eruption in Indonesia, Toba. It is said that the eruption was so great that the ash reached the South China Sea and the Arabian Sea. Through the ash layers found in South Asian regions, scientists estimate the dates of dispersal of modern humans to South Asian regions. In Jwalapuram, in the Jurreru River valley of India, stone tools assemblages were found in Toba ash layers. Those stone tools were different from stone tools which were previously found and considered to be made by Homo heidelbergensis who lived from 300,000 years ago to 250,000 years ago. Some of the artifacts found in the ash layers, with unidirectional and bidirectional bladelike core technology, showed closer affinities to African Middle Stone Age from 90,000 years ago to 60,000 years ago. Since this indicates humans already reached India by 74,000 years ago and survived from Toba eruption, this discovery was surprising as it gave much earlier dates of arrival in India and many scientists assume the great eruption must have influenced greatly to ecosystems of the region. Due to lots of questions surrounding presence of Homo sapiens in the period and lack of evidence, the time and the route of dispersal in India are still debated.
Genetic analysis makes clearer when and in which way humans reached to southern parts of Asia. As mentioned in the previous chapter, haplogroup L3, after they migrated out of Africa about 85,000 years ago, was divided into haplogroups M, N, and R. The presence in each region of the same three founder haplogroups differentiated into distinct subhaplogroups suggests that a rapid coastal dispersal took place from about 65,000 years ago around the Indian Ocean and on to Australasia. More specifically, analysis of western, southern, and eastern Eurasians and Australasian mtDNAs suggests that humans arrived in India about 66,000 years ago and in Australasia about 63,000 years ago. Archaeological data gives more recent dates ? 50,000 years for Australia and 45,000 years for southeast Asia, but early evidence may have disappeared as sea level rises. They suggest the coastal trail was likely the only route taken during the Pleistocene epoch of Eurasia and the process of migration from India to Australasia was very rapid. It is supposed that migrating populations expanded rapidly along the coastlines of southern Asia, southeastern Asia, and Indonesia and arrived in Malaysia and the Andaman Islands by at least 55,000 years ago since coastal dispersal would have required only limited economic adaptations from one coastal location to another and provided them with affluent foods.  Although there is lack of archaeological evidence supporting coastal movement, it is likely that traces of southern coastal movement might have disappeared as the sea level has risen greatly today compared to that in Pleistocene Epoch. In addition, archaeological assemblages found in the sites of Patne in western India, which show striking resemblances to those found in eastern and southern Africa, Jwalapuram in southeast India and Batadomba-lena in Sri Lanka also give us some pictures of the route which modern humans might have taken.
A picture below is a map of possible dispersal routes of anatomically and genetically modern human populations from Africa to Asia and Australia.
Images 1 
For Southeast Asia, it was previously believed that people moved from north Asia to the south, however, some scientists claim that the population moved from the south to the north. In fact, according to Oppenheimer's mitochondrial analysis on Malaysian people, most of Malaysian people were not from Northeast Asia; however, people living in northern China, Taiwan, and Japan were descended from Southeast Asian people. In addition, Toba ash layers were also found in Southeast Asia with stone tools. Despite such claims, it still seems uncertain if Homo sapiens already reached Southeast Asia by 74,000 years ago.
It is thought that Homo sapiens reached Southeast Asian regions at least until about 45,000 years ago as seen in the archaeological evidence found in Niah Cave, Borneo. In it, a skull of a human was found, dated to about from 45,000 years ago to 39,000 years ago. Other human traces such as burned animal bones which were dated back to from 46,000 years ago to 33,000 years ago were found near the cave. It is persuasive that Homo sapiens might have reached this region and lived since it is supposed to have been warm, humid, and appropriate for humans to live then.
IV.2.2.2 Within Central, North and East Asia
From an analysis of mitochondrial DNA of North Asian people, it is found that they spread from M and N lineages of South Asian people, suggesting that our ancestors reached north Asia after the spread into other parts of continents. In addition, mixed lineages of Asians and Europeans found in mitochondrial DNA of Siberians show that Siberians migrated into the region through complicated process, and varied genes of people in Altai regions indicate that they were first people to settle in that region.
Several possible routes could have been taken when Homo sapiens moved into central Asia and Northeast Asia. Oppenheimer shows how people could move into central Asia by going around Himalayas and going inland.  Some might have crossed Khyber Pass in the west of Himalayas and gone to the north, and some might have entered into central Asia through Southeast Asia. Perhaps, they could have arrived in central Asian regions through Silk Road, or through crossing Altay Mts. However, it is difficult to find exact routes they have taken since people in Siberia have tangled structures of mitochondrial DNA.
From the oldest existing archaeological evidence found in Kara-Bom in central Asia, it seems that ancient hominids such as Homo neanderthalensis already lived there. Doctor Ted Goebel suggests that the first time southern Siberia was settled is from 200,000 years ago to 100,000 years ago by ancient hominids and Homo sapiens migrated into the regions from about 45,000 years to 35,000 years ago.
While it was believed that modern human s reached northern Siberia after the last ice age passed about 18,000 years ago, archaeological assemblages found in Yana disproved this belief as they were dated to be from 30,000 years ago. This shows that humans reached arctic regions way before the last ice age.
Genetic analysis of Y chromosomes shown in 2001, Science, gives a lot of information about migrations of East Asian people. Researchers concluded that from the existence of mutation M168 which appeared in Africa about 80,000 years ago in DNAs of all Chinese people, East Asian people are originated from Africa. More varied forms of Y chromosomes found in south Asian regions reveal that people spread to south from north. This analysis also suggests that Homo sapiens first migrated into East Asia from about 60,000 years ago to 25,000 years ago.  C and Z lineages of genes are only found in northern Asian people and Oppenheimer claims from this that they were people who settled in Altai and Siberian regions from 50,000 years to 40,000 years ago, originated from India. It was also revealed that some of them went to the west, reaching Europe and some of them proceeded to the east, reaching northern China. These genetic analyses disprove China origin theory which argues that modern Chinese people has been independently originated from Beijing Man(Homo erectus pekinesis), who lived in a million years ago. Korea and Japan were supposed to be first inhabited by Homo sapiens who moved from Southeast Asia through coastal lines from around 40,000 years ago to 37,000 years ago.
There are not many archaeological evidence on exactly when and how people could cross the sea and reach Australia. The oldest site along the way between Australia and Southeast Asia is Jerimalai in East Timor where traces of humans from 42,000 years ago were found, but still it does not give conclusive information on human journey to Australia. More important traces of humans were found in Willandra Lakes. Foot prints of humans, which are supposed to be from 23,000 years - 19,000 years ago according to OSL dating, were found, and humans bones named as Mungo 1 and Mungo 2 were found. These bones were initially measured to be from 60,000 years ago in 1999, but later, measured to be from 40,000 years ago. Additionally, in northern Australia, archaeologists have found humans traces of 60,000 years old in Malakunanja, Nauwalabila, and Jinmium.
Ecological data also give information about humans in Australia. It is believed that lots of Megafauna such as Procoptodon goliah, which is a big kangaroo, lived in Australia, and became extinct about 20,000 years before the last ice age, which is from 50,000 years ~ 40,000 years ago. Some scientists believe that their extinction was caused by people who migrated into Australia. The people might have hunted those animals, or changed ecosystem, and led them to extinction. 45,000 years ago, there was a big forest fire which greatly reduced forest of Australia and some scientists guess that humans might have been involved in causing the fire.
DNA analysis reveals that Australians have M lineages and N lineages both of which are originated from Africa and they started to live before at least 40,000 years ago when two lineages were first separated from one lineage. Mitochondrial DNA genealogy shows that about 50,000 years ago, a group of people moved to Australia and New Guinea.
Most of genetic and archaeological studies indicate that people first came to Australia around 60,000 years - 50,000 years ago. However, since it means that the time they first reached Australia is 20,000 years before the time people first moved to Europe, lots of people do not accept this argument.
IV.4.1 From Asia to Europe
Although some archaeologists argue that modern Homo sapiens reached Europe through Egypt from Africa, it is more rational to believe that modern humans crossed Persian Gulf and Mediterranean Sea, and arrived at Europe. Stephen Oppenheimer claims that they could not cross Middle East since the route to Middle East from India and Arabian Peninsula was blocked by Zagros Mts, Syrian Desert, and Arabian Desert for a long time. And by 50,000 years ago, they could enter the route as the climate became warm. Therefore, it is thought that many traces of them would exist in Levant or in Turkey. In fact, remains of Homo sapiens are being discovered in these regions. For example, in Ksar Akil of Beirut in Lebanon, archaeologists found strata of Upper Paleolithic Era. There, they found Upper Paleolithic artifacts from about 50,000 - 43,000 years ago and bones of Homo sapiens which show Homo sapiens existed in that era. Also, in Ucagizli Cave of Turkey, tools made of antler were traced back to 43,000 - 41,000 years ago. This archaeological site is thought as important Upper Paleolithic remains since Aurignacian culture spread from east to west about 40,000 - 35,000 years ago through the site. Most scientists agree modern humans who lived in Levant spread from Turkey and Europe through these regions although there are disputes in detail.
After passing Levant, humans would have to cross Bosporus Straight and Dardanelles Straight. They may have moved along the shoreline or riverside or by sailing. Geological studies show that during the Pleistocene Epoch, the sea level was low and Bosporus was part of the continent. However, due to Bay of Izmit located between the Sea of Marmara and the Black Sea, they anyway had to cross the sea to go to Europe. From Upper Paleolithic relics found along the shore of Mediterranean Sea and Black Sea, modern humans probably used these two routes. In Baro Kiro of Bulgaria, lots of stone blades from 43,000 years ago were found, and they were tools from just before Aurignacian culture. Also, along Danube River, several Upper Paleolithic sites were found. People who migrated through the western shore of Black Sea may have passed Danube Delta and then, spread inside of Europe. These sites were originally traced back to be from 46,000 - 35,000 years ago by old radiocarbon dating, but, recently estimated to be from 46,000 - 41,000 years ago. Within this relatively short period, modern humans might have moved into Europe. They could have migrated in faster rate probably because of warmer climate during interglacial epoch.
IV.4.2 Dissemination within Europe
Human migration within Europe is often explained with Upper Paleolithic culture such as Aurignacian culture. In 1931, in Vogelherd of Germany, scientists have found lots of Aurignacian tools and bones of Homo sapiens in the strata of Upper Paleolithic epoch. Since then, Vogelherd site with other Aurignacian remains such as Hohle Fels of Germany, Willendorf of Austria, was used as the evidence that early modern Homo sapiens settled in middle Europe along Danube River. However, as bones found there were estimated to be from 4000 - 5000 years ago in 2002, the connection between Homo sapiens and Aurignacian culture got weaken. But, still there are other remains which show the relations between Homo sapiens such as Ksar Akil of Lebanon which is from 45,000 - 40,000 years ago, Mladec of Czech republic from 35,000 - 34,000 years ago.
According to mitochondrial DNA analysis of European, two haplogroups were discovered: H haplogroup which is the most common in European, and Pre-V haplogroup which is supposed to have appeared in the Caucasus Mountains in eastern Europe and spread all over Europe around 30,000 ~ 20,000 years ago. It is thought that they spread new culture called Gravettian culture to Europe. The period between 30,000 years ago and 20,000 years ago was also when the climate greatly lowered down as the last ice age came. As it got colder and glaciers gradually moved down to south, Homo sapiens may have also moved down to warmer southwest regions of Europe. Last ice age made northern Europe unlivable for humans but Iberian Peninsula and France had less climatic changes, located close to Atlantic Ocean. In fact, in France, we can find evidence that modern humans actually started to migrate to southwest Europe. In the Vezere Valley, there is early Aurignacian site, Abri Castanet where Homo sapiens started to live from 33,000 years ago. Although the date is a bit early, it might have been still cold then. People who migated in that region seem to develop their own culture as seen in many cave painting found in southern France and northern Spain.
As the climate rose again as the Ice Age passed, European spread to all over Europe. They may have moved to north of Loire by 16,000 years ago and Britain by 13,000 years ago. The climate change also rendered modern humans to have new cultures such as Magdalenian culture.
IV.4.3 Homo sapiens and Homo neanderthalensis
The earliest Homo sapiens bone found in Europe is jawbone excavated in Pestera cu Oase of Romania which is estimated to 36,000 ~34,000 years ago. However, there was another hominid living in Europe, Homo neanderthalensis from 35,000 years ago. To claim that Out of Africa theory is true, we may need to distinguish Homo neanderthalensis from Homo sapiens and prove that people today are not descended from Homo neanderthalensis.
It is possible to find many physical and genetic differences between Homo sapiens and Homo neanderthalensis. Neanderthals had shorter arms and legs, and long flat skull while Homo sapiens had circular skull. In addition, it was found that Neanderthals had larger face and nose and their lower jawbones bulged. Some scientists give a skull found in Cioclovina cave in Romania in 1941, claiming that it resembles a skull of Neanderthals. But, a research done in Max Planck Institute shows that Cioclovina skull does not have resemblance to a skull of Neanderthals and it is more similar to Homo sapiens. Genetic research conducted in the same institute in 1997 compared DNA of Neanderthals and Homo sapiens and concluded that they are completely different and the two species were separated 600,000 years ago. For multiregional origin theory to be correct, mitochondrial DNA of Neanderthals should be genetically close to that of modern European but the study shows that DNA of Neanderthals is different from that of European and Asian. Another study analyzed DNA in fossils of modern Homo sapiens which is 25,000 years old and found that it is also very different from DNA of Neanderthals.
However, it is hard to assert that the two species did not mate. Very recent studies reveal whether they crossbred or not. According to a study of Max Planck Institute led by Svante Paabo presented in Science in 2010, 1 and 4 % of the genomes of people in Eurasia are derived from Neanderthals. This suggests the two species actually mated and made offspring. The study gives that while the genome of Neanderthals challenges to previous simplest version of Out of Africa theory, still it continues to support the view that the vast majority of genetic variants that exist at appreciable frequencies outside from Africa came from Africa with the spread of anatomically modern humans.
Meanwhile, Homo neanderthalensis is supposed to have been completely extinct in Europe by 24,000 years ago. There are many hypotheses about why the species got extinct. Large proportions of them suggest Homo sapiens as the reason of their extinction, but how Homo sapiens made Neanderthals extinct varies from each other. For example, one study suggests Neanderthals disappeared because Homo sapiens ate them. Another hypothesis is that numerical inferiority of Neanderthals made Neanderthals extinct by Homo sapiens. A very recent study presented in Human Ecology in 2011 claims continuous hybridization between the two species reduced genomes of Neanderthals whose number was much less than that of Homo sapiens and thus, Neanderthals were absorbed into Homo sapiens. For now, there seems to be no exact answer to explain the extinction of Neanderthals, but we can guess that Homo sapiens might have given influence on their extinction.
Genetic research indicates that there are five mtDNA haplogroups A, B, C, D, and X and two Y-chromosome haplogroups C and Q in Native Americans, and all these were originated from southern Siberia from the Altai to Amur regions. It indicates that all Native Americans came from Asia, and "Solutrean Hypothesis" which suggests ancestors of Clovis people came from the Iberian Peninsula is not true. While early genetic research shows that there were five large movement of population from Siberia to North America, genetic and linguistic studies conducted in 1980s suggests that there were three migrations since languages of Native Americans can be classified into three: Amerind, Nadene, and Aleut-Eskimo. Y chromosome analysis of 2004 concludes that there were two great movements as Y chromosome haplogroups are divided into Q and C. But, it seems that this genetic variety is not because there were two migrations, but because groups of people who initially migrated had diverse Y chromosomes. Recent DNA analysis also suggests that there was only one great movement.
Genetic researches illustrates that ancestors of Amerind living in Northeast Asia passed Beringia between 36,000 and 16,000 years ago and moved to America. From diversity of genes, it is supposed that the number of people who moved into America was only 5,000. While Mitochondrial DNA analysis sees that population in America increased largely around 18,000 - 15,000 years ago, Y chromosome analysis gives latter dates for population increase, around 17,000 - 10,000 years ago. Although there is a difference between the two analyses caused by genetic assumption that mutations are regularly occurred, overlapping periods between the two would be rather accurate.
Despite these genetic researches suggesting human migration to America were held in less than 20,000 years, Stephen Oppenheimer believes ancestors of Native Americans arrived at Beringia long before the last Ice Age, isolated from other Asians, and then moved into America before glaciers blocked American continent. He gives genetic and linguistic diversity in South America than in North America for its evidence. He supposes that before the Ice Age, people already dispersed into South America and as the glaciers covered North America, people no longer lived in North America and they moved into North America again when it got warmer.
Until a recent date, it was widely believed that around 13,500 years ago, group of people using stone tools called Clovis moved to North America as lots of stone tools were found in Clovis, New Mexico in 1930s. The time when Clovis people moved to America is coincided with the period when melted glaciers opened Asian corridor, so that they can move to America through it. While fossils of megafauna such as mammoth and smilodon found in La Brea Tar Pits suggest there were diverse animals in ancient California, those big animals after 13,000 years ago are no more found. Some scientists claim that the period is consistent with the period when Clovis people moved to North America, and thus their hunting resulted in the extinction of those animals. Lots of Clovis tools are discovered such as Gault in Texas, Dent in Colorado, and Naco in Arizona. From these sites, it seems that Clovis culture moved from north to south and along the shoreline from southern Canada to Costa Rica. Recent radiocarbon dating indicates that this Clovis culture spread fast between 13,200 years and 12,800 years ago. However, a lot of evidence, which suggest that Clovis people were not the first people in America, is being found.
In Gault, below the stratum where Clovis remains were found, other artifacts were discovered, and they were from 14,400 years ago. Meadowcroft in Pennsylvania is also one site which shows people lived before Clovis though its date which is estimated 22,000 ago is still controversial. In Wisconsin, evidence that people hunted Mammoth 14,800 - 14,200 years ago was found and in Page-Ladson of Florida, stonetools from 14,400 years ago were excavated. In Paisley Cave of Oregon, archaeologists unearthed 14,100 years old human excretion. There are several sites which are claimed to be before 15,000 years ago but such evidence is quite scanty. But, that people could have lived 15,000 years ago in America is not a weak assumption. Other evidence for earlier settlement of humans in America exists in South America. In Pedra Pintada cave of Brazil, traces of humans from 13,000 years ago such as burned wood, stone tools, bones of fish, etc were found. This period is similar to when Clovis lived in North America which is 8000 km away from the cave, and therefore, people must have lived in South America before Clovis moved to America. More earlier and conclusive site is found in Monteverde of Chile. In Monteverde, lots of remains such as animal bones, plants residue, footprints of a child, foodstuffs were found; they were estimated to be from 14,600 - 14,400 years ago. These earlier archaeological proofs argue against the claim that modern humans moved to America after the glaciers melted.
Then, how they moved from Asia to North America ? Genetic, archaeological, and geological researches show modern humans migrated along the shore probably by sailing. According to a research done in Haida Gwaii Island, radiocarbon dating of plant fossils shows that glaciers melted completely around 18,000 years ago in the island. Since the sea level was low and the island was connected to the continent then, animals, plants and human could have easily migrated through the island. This research indicates that glaciers started to melt already 17,000 years ago from western seashore. Pollen found in Dogfish Bank tells that the island was connected to Canada and various plants such as grasses and mosses grew then. While there were still glaciers inland, glaciers would have disappeared in shoreline from Alaskan Bay to British Columbia 16,000 years ago. Pine trees start to grow in the region by 15,600 years ago, and other plants also started to grow as it got warmer. Bones of bears from 17,000 years ago discovered in Whistler, Canada also give hints of human migration. Mitochondrial DNA analysis of bears¡¯ bones shows that they moved from North America through Beringia just like humans. If bears could survive and travel then, humans also could survive and move to America with those animals. From this evidence, it can be derived that humans could move to America much earlier than the Asian corridor appeared around 13,000 years ago. They probably had no problem with sailing since they already could sail across the sea between Asia and Australia as early as about 60,000 years ago.
IV.6 The Islands
For islands, human migration generally took place much later than they spread within continents. Arrivals of humans in some major islands or archipelagos, which are not mentioned in previous chapters, such as Madagascar, Greenland, British Isles, Taiwan, and Polynesian regions shall be explained in this chapter
From the ethnicities of people in Madagascar, researchers guess that it was first inhabited between 300 BCE and 500 CE by Austronesian peoples from Borneo in the Indonesian archipelago. Later, people from different ethnicities such as Bantu migrants crossing the Mozambique Channel in 1000 CE, Arabs, East African, Malay and so on subsequently reached Madagascar.
For British Isles, it is supposed to be first inhabited before the last ice age when it was joined to the European mainland. The first settlement of modern humans in Great Britain is supposed to have occurred around 30,000 years ago, and it might have been repopulated after it was separated from mainland. The first settlement in Ireland is thought to have happened around 8000 BC by hunter-gatherers from continental Europe, via a land. In Greenland, the first inhabitation of humans is thought to have occurred about 2500 BC by the Paleo-Eskimo who were from the Arctic region from Chukotka.
Taiwan, which is an island country located about 150 km from China, is supposed to be first settled in 30,000 years ago by modern Humans. However, it is supposed that current aborigines of Taiwan descend from Austronesian people who moved into Taiwan about 4,000 years ago from mitochondrial DNA analysis and linguistic studies
In Polynesian regions, people who are thought to come from Taiwan and speak Austronesian languages spread throughout the islands of Southeast Asia about 3000 BC - 1000 BC. Linguistic and archaeological evidence support that Polynesian people are originated from Taiwanese. Among the islands in Polynesia, Hawaii is supposed to have been settled around 1,000 - 1,200 AD according to recent study using reliable radiocarbon dates and Easter Island was first settled around 1,200 AD. Radiocarbon dating, evidence of deforestation, and mitochondrial DNA analysis of Maori population suggest New Zealand was first settled by Eastern Polynesians between 1,250 and 1,300.
There are still lots of researches projects going on about exactly when and how modern humans migrated from a region to another. However, from existing archaeological, genetic, and geological theories and evidence, we can make rough guess about the journey of modern human. First of all, all modern humans are most likely originated from eastern Africa around 200,000 years ago. Then, other continents would have been subsequently settled. A group of modern Homo sapiens may have reached Asia around 80,000 years ago through crossing Red Sea and become ancestors of people in non African regions. After they arrived at Asia, they spread to all over Asia and part of them would reach Australia by moving along the seashore of Southeast Asia around 60,000 years ago. As the climate got warmer between 50,000 and 40,000 years ago, humans could get into Europe by crossing current Bosporus straight along the coastline and spread and develop their cultures in Europe for a long time. Lastly, as glaciers started to melt from western seashore, humans living in Siberia entered America by passing Beringia and sailing along the coastline between Asia and Europe around 15,000 years and 14,000 years ago.
However, it seems that these theories, which are widely accepted now, can always be revised by new evidence and new researches, considering how previous theories about human migration have been contradicted and modified by more reliable hypotheses. With better dating technology and precise genetic analysis, probably in the future, we would be able to draw more accurate pictures on our ancestors¡¯ journeys to all over the world.
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(2) Wikipedia, Neanderthal
(3) National Geographic News, May 7 2007
(4) Bradshaw Foundation, 2003
(5) National Geography, the Genographic Project, Atlas of Human Journey
(7) BBC, the Incredible Human Journey Episode I Out of Africa
(9) Bradshaw Foundation, 2003
(10) Science Magazine, 13 May 2005
(11) Wikipedia, Recent African origin of modern humans
(12) Bradshaw Foundation, 2003, Gates of Grief
(13) Wikipedia, Recent African origin of modern humans
(14) Science Magazine, 28 January 2011
(15) Science Magazine, 6 July 2007
(16) Science Magazine, 13 May 2005
(19) Science Magazine, 11 August 2006
(21) Science Magazine, 13 May 2005
(22) Bradshaw Foundation, 2003, Four routes into Central Asia
(23) Science Magazine, 11 May 2001 A Tale of 12,000 Y Chromosomes
(24) Science Magazine, 7 May 2010
(25) Science Magazine, 14 March 2008
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2. BBC, the Incredible Human Journey Episode II Asia, 17 May 2009
3. BBC, the Incredible Human Journey Episode III Europe, 24 May 2009
4. BBC, the Incredible Human Journey Episode IV Australia, 31 May 2009
5. BBC, the Incredible Human Journey Episode V The Americas, 14 June 2009
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14. Science Magazine, 11 August 2006 Article: Going East: New Genetic and Archaeological Perspectives on the Modern Human Colonization of Eurasia
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Homo_(genus), URL: http://en.wikipedia.org/wiki/Homo_(genus)
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Africa's genetic secrets, unlocked URL: http://news.bbc.co.uk/2/hi/science/nature/8027269.stm
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Modern Humans Did Not Admix with Neanderthals during Their Range Expansion into Europe URL: http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020421
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The Journey of Man - A Genetic Odyssey. Random House. pp. 138-140. URL: http://books.google.com/books?id=WAsKm-_zu5sC
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What does it mean to be human ? URL: http://humanorigins.si.edu/
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Both Australian Aborigines and Europeans Rooted in Africa, URL: http://news.softpedia.com/news/Both-Aborigines-and-Europeans-Rooted-in-Africa-54225.shtml.
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From DNA Analysis, Clues to a Single Australian Migration, URL: http://www.nytimes.com/2007/05/08/science/08abor.html?ex=1187236800&en=3051874ea83b3233&ei=5070
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Aborigines, Europeans Share African Roots, DNA Suggests URL: http://news.nationalgeographic.com/news/2007/05/070507-aborigines-dna.html
42. Wikipedia Article:
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