現時生物學及考古學界一般認為，人類起源於類人猿。目前對現代人類的早期演化歷程主要有兩種理論，即單地起源說和多地起源說，19世紀時西方國家的人類學家抱有種族歧視觀念，大部分同意多地起源說，認為白種人和其它人種起源不同，從根本上就處於一個優越的地位。20世紀的新考古發現、基因檢測技術發展和思想進步，導致大部分科學家同意單地起源說，但隨著新考古發現的不斷出現，有越來越多的科學家開始考察多地起源說。
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| 生物學 | 解剖學 | 交流 | 進化 | 遺傳學 | 外貌 | 文化 | 文明 | 社會 | 科技 | 藝術 | 心靈 | 人性 | 性特徵 | |
遺址是指人類活動的遺跡，屬於考古學概念。遺址的特點表現為不完整的殘存物，具有一定的區域範圍，很多史前遺址、遠古遺址多深埋地表以下。埋藏地下的遺址的發現多與人類活動有關，如農業生產、建築工地施工等；很多古代遺址屬於探險發現。古代城市、古代建築遺址多為殘垣斷壁，各種生活用品表現為不殘破和不完整，但可以通過考古和人類學研究尋找人類生活軌跡。很多遺址屬於戰爭、災難之後的遺存。
1978年--中國人類學家吳汝康率領的發掘隊，在雲南省祿豐縣石灰壩發現一具800萬前的臘瑪古猿頭骨化石。
1992年發現於雲南保山縣羊邑清水溝煤礦的煤系層中。化石為一塊下頜骨 和一枚前臼齒。其地質年代為中新世晚期到上新世，距今約800－400萬年。下 頜骨的形態很像祿豐古猿，但臼齒上的齒冠寬短，比祿豐古猿更接近於南方古 猿。南方古猿是由猿到人進化過程的主要代表，保山古猿正好介於祿豐古猿與 南方古猿之間。因此，它的發現填補了人類進化史上的一段空白。
祿豐古猿1975－80年發現於雲南祿豐縣石灰壩煤場的第三紀褐煤地層內。經過多次的 發掘，發現不少臘瑪古猿化石，包括一具殘頭骨、若干個頜骨和上百顆牙齒。 其形態比臘瑪古猿進步，更接近於人類的早期形態。這種古猿化石在世界上尚 屬首次發現。與古猿化石共生的有三趾馬、劍齒虎、無角犀、河豬等中新世和 上新世的動物化石。化石所在地層的時代，為中新世的晚期或上新世的早期， 距今約800萬年。
在科學中，露西（Lucy）是1974年在衣索比亞發現的南方古猿阿法種（en:Australopithecus afarensis）的古人類化石的代稱。露西生活的年代是320萬年之前，因此被認為是第一個直立行走的人類，是目前所知人類的最早祖先。
1974年11月24日，美國古人類學家唐納德·詹森，伊夫·科本斯和蒂姆·懷特在衣索比亞的阿法爾凹地發現一具骨人類的化石。根據當時慶祝發現而播放的披頭士樂隊的一首歌《Lucy in the Sky with Diamonds》將她命名為露西（Lucy）。 露西是一具40%完整的骨架，生前是一個20多歲的女性，根據骨盆情況推算生過孩子。露西的腦容量只有400毫升。
The Olduvai Gorge or Oldupai Gorge is commonly referred to as "The Cradle of Mankind." It is a steep-sided ravine in the Great Rift Valley, which stretches along eastern Africa. Olduvai is in the eastern Serengeti Plains in northern Tanzania and is about 30 miles long. The gorge is named after the Maasai word for the wild sisal plant Sansevieria ehrenbergii, commonly called Oldupaai.
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It is one of the most important prehistoric sites in the world and has been instrumental in furthering understanding of early human evolution. Excavation work there was pioneered by Louis and Mary Leakey in the 1950s and continued into the twenty first century by Professor Fidelis Masao of the Open University of Tanzania supported by Earthwatch; there have also been teams from Rutgers University. Millions of years ago, the site was that of a large lake, the shores of which were covered with successive deposits of volcanic ash. Around 500,000 years ago seismic activity diverted a nearby stream which began to cut down into the sediments, revealing seven main layers in the walls of the gorge.
The stratigraphy is extremely deep and layers of volcanic ashes and stones allow radiometric dating of the embedded artifacts, mostly through potassium-argon dating. The first artifacts in Olduvai (pebble tools and choppers) date to circa 2 million years ago but fossil remains of human ancestors have been found from as long as 2.5 million years ago.
The earliest archaeological deposit, known as Bed I, has produced evidence of campsites and living floors along with stone tools made of flakes from local basalt and quartz. Since this is the site where these kinds of tools were first discovered, these tools are called Oldowan. It is now thought that the Oldowan toolmaking tradition started about 2.6 million years ago. Bones from this layer are not of modern humans but primitive hominid forms of Paranthropus boisei and the first discovered specimens of Homo habilis.
The Olduvai Gorge bears the distinction of having the oldest known evidence of Elephant consumption, attributed to Homo ergaster around 1.8 million years ago.
Above this, in Bed II, pebble tools begin to be replaced by more sophisticated handaxes of the Acheulean industry and made by Homo ergaster. This layer dates to around 1.5 million years ago.
Beds III and IV have produced Acheulean tools and fossil bones from more than 600,000 years ago.
During a period of major faulting and volcanism roughly 400,000 to 600,000 years ago, the Masek Beds were made.
Beds above these contained tools from a Kenya-Capsian industry made by modern humans and are termed the Masek Beds (600,000 to 400,000 years ago), the Ndutu Beds (400,000 to 32,000 years ago), and the Naisiusiu Beds (22,000 to 15,000 years ago).
Also located on the rim of the Gorge is the Olduvai Gorge Museum. This Museum presents exhibitions pertaining to the Gorge's history.
Olduvai is the location of the first monolith in Arthur C. Clarke's 2001: A Space Odyssey series of books.
Olduvai is also the theme of the Olduvai theory, which states that industrial civilization will have a lifetime of less than or equal to 100 years.
The variant "Oldupai" is the Maasai word for the wild Sisal plant that grows in the gorge; some claim the more common spelling "Olduvai" is the result of a mis-hearing of the word by colonial visitors. The latter spelling is not used locally.
Olduvai is the name of the Mars location in the Doom movie.
The following charts give a brief overview of several notable primate fossil finds relating to human evolution. As there are thousands of fossils, this overview is not meant to be complete, but does show some of the most important finds. The fossils are arranged by approximate age as determined by radiometric dating and/or incremental dating. The species name represents current consensus, when there is no clear scientific consensus the other possible classifications are indicated; deprecated classifications may be found on the fossil's page. Not all the fossils shown are considered direct ancestors to Homo sapiens but are very closely related to direct ancestors and are therefore important to the study of the lineage.
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| Image | Name | Age | Species | Date discovered |
Place | Discovered by |
|---|---|---|---|---|---|---|
| Aegyptopithecus
zeuxis image at Skulls Unlimited |
DPC 2803 | >31 mya | Aegyptopithecus zeuxis | Egypt | Elwyn Simons | |
| Proconsul
africanus image at Skulls Unlimited |
KNM RU 7290 | 18 mya | Proconsul africanus | 1948 | Kenya | Mary Leakey |
| Image | KNM WK 16999 | 16-18 mya | Afropithecus turkanensis | 1986 | Kenya | Richard Leakey |
| Image | KNM WK 16950 | 16-18 mya | Turkanapithecus kalakolensis | 1986 | Kenya | Richard Leakey |
| Image | IGF 11778 | 8 mya | Oreopithecus bambolii | 1872 | Italy | Paul Gervais |
| Image | IVPP PA644 | 8 mya | Lufengpithecus lufengensis | 1978 | China | |
| Sivapithecus
indicus image at Skulls Unlimited |
GSP 15000 | 8 mya | Sivapithecus indicus | 1979 | Pakistan | D. Pilbeam and S. M. Ibrahim Shah |
| Name | Age | Species | Date discovered |
Place | Discovered by | |
|---|---|---|---|---|---|---|
| Laetoli
footprint image at Modern Human Origins |
Laetoli Footprint | 3.7 mya | Bipedal hominid | 1976 | Tanzania | Mary Leakey |
| LH
4 image at Modern Human Origins |
LH 4 | 3.6 - 3.8 mya | Australopithecus afarensis | 1974 | Tanzania | Mary Leakey |
| KNM-WT
40000 image at Modern Human Origins |
KNM WT 40000 | 3.5 mya | Kenyanthropus platyops | 1999 | Kenya | Justus Erus |
| Stw 573 (Little foot) | 3.3 mya | Australopithecus ? | 1994 | South Africa | Ronald J. Clarke | |
| DIK-1 (Selam) | 3.3 mya | Australopithecus afarensis | 2000 | Ethiopia | Zeresenay Alemseged | |
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AL 200-1 | 3 - 3.2 mya | Australopithecus afarensis | 1975 | Ethiopia | Donald Johanson |
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AL 129-1 | 3 - 3.2 mya | Australopithecus afarensis | November 1973 | Ethiopia | Donald Johanson |
| K 12 (Abel) | Australopithecus bahrelghazali | 1995 | Chad | Michel Brunet | ||
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AL 288-1 (Lucy) | 3.2 mya | Australopithecus afarensis | November 30, 1974 | Ethiopia | Donald Johanson |
| AL444-2 image at Modern Human Origins |
AL 444-2 | 3 mya | Australopithecus afarensis | 1991 | Ethiopia | Bill Kimbel |
| Name | Age | Species | Date discovered |
Place | Discovered by | |
|---|---|---|---|---|---|---|
 |
STS
5 (Mrs. Ples) |
2.6 - 2.8 mya | Australopithecus africanus | 1947 | South Africa | Robert Broom |
| STS
14 image at Modern Human Origins |
STS 14 | 2.6-2.8 mya | Australopithecus africanus | 1947 | South Africa | Robert Broom |
| STS
52 image at Modern Human Origins |
STS 52 | Australopithecus africanus | ||||
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STS 71 | 2.5 mya | Australopithecus africanus | 1947 | South Africa | Robert Broom |
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Taung
1 (Taung Child) |
2.5 mya | Australopithecus africanus | 1924 | South Africa | Raymond Dart |
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KNM
WT 17000 (The Black Skull) |
2.5 mya | Paranthropus aethiopicus | 1985 | Kenya | Alan Walker |
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TM 1517 | 2 mya | Paranthropus robustus | 1938 | South Africa | Gert Terblanche |
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Sahelanthropus tchadensis • Orrorin tugenensis • Ardipithecus • Kenyanthropus platyops Australopithecus: A. anamensis • A. afarensis • A. bahrelghazali • A. africanus • A. garhi Paranthropus: P. aethiopicus • P. boisei • P. robustus
Humans and Proto-humans
Homo: H. habilis • H. rudolfensis • H. georgicus • H. ergaster • H. erectus (H. e. lantianensis • H. e. palaeojavanicus • H. e. pekinensis • H. e. soloensis) • H. cepranensis • H. antecessor • H. heidelbergensis • H. neanderthalensis • H. rhodesiensis • H. floresiensis • Homo sapiens (H. s. idaltu • H. s. sapiens)
Topics: Timeline
of human evolution • List of
human evolution fossils • Human
evolutionary genetics
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Human and Chimpanzee
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Subtribe Panina Subtribe Hominina |
Hominini is the tribe of Homininae that only includes humans (Homo), chimpanzees (Pan), and their extinct ancestors. Members of the tribe are called hominins (cf. Hominidae, "hominids"). The subtribe Hominina is the "human" branch, including genus Homo and its close relatives, but not Pan.
The creation of this taxon is the result of the current idea that the least similar species of a trichotomy should be separated from the other two. Through DNA comparison, scientists believe the Pan/Homo divergence was completed between 5.4 to 6.3 million years ago, after an unusual process of speciation that ranged over four million years.[1] It is interesting to note that no fossil species on the Pan side of the split have been determined; all of the extinct genera listed to the right are ancestral to Homo, or are offshoots of such. However, both Orrorin and Sahelanthropus existed around the time of the split, and so may be ancestral to both humans and chimpanzees.
In the proposal of Mann and Weiss (1996),[2] the tribe Hominini includes Pan as well as Homo as separate subtribes. Homo (and, by inference, all bipedal apes) is by itself only in the subtribe Hominina, while Pan is in the Panina subtribe.
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This primate-related article is a stub. You can help Wikipedia by expanding it. |
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Hominini
Sahelanthropus tchadensis • Orrorin tugenensis • Ardipithecus • Kenyanthropus platyops Australopithecus: A. anamensis • A. afarensis • A. bahrelghazali • A. africanus • A. garhi Paranthropus: P. aethiopicus • P. boisei • P. robustus
Humans and Proto-humans
Homo: H. habilis • H. rudolfensis • H. georgicus • H. ergaster • H. erectus (H. e. lantianensis • H. e. palaeojavanicus • H. e. pekinensis • H. e. soloensis) • H. cepranensis • H. antecessor • H. heidelbergensis • H. neanderthalensis • H. rhodesiensis • H. floresiensis • Homo sapiens (H. s. idaltu • H. s. sapiens) |
根據20世紀後半期的考古發現，人類單地起源說認為全世界的人類都起源於東非的纖細型南方古猿的一個群體。
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早期人類發源於東非，他們跨越紅海曼德海峽，抵達阿拉伯半島及兩河流域。
至此遷移路線分三路，一部份人類走北路。經安納托利亞半島與高加索山脈遷移到北歐平原（橘色圓圈）及歐俄平原。歐俄平原的人類再由海路經冰島、格陵蘭遷移到美洲大陸的紐芬蘭。
另一部份則走中路。經過伊朗高原、中亞草原遷移到西西伯利亞平原。再分數枝，分別遷移到東北平原、華北平原及中西伯利亞高原。 其中西伯利亞高原的人類又經白令陸橋（後來的白令海峽）遷移到美洲大陸的阿拉斯加並深入（藍色圓圈）。 東北平原的人類經朝鮮半島遷移到日本群島。 華北平原的人類再走向嶺南丘陵遷移到華南。
最後一支走南線。沿著海岸線，由阿拉伯半島通過荷姆茲海峽遷移到南亞次大陸（紅色圓圈），沿海岸線抵達東南亞半島及華南，再由台灣島及馬來半島遷移到東南亞群島、新幾內亞、澳大利亞（紅色圓圈）及太平洋島嶼。之後有一支人類再西行遷移到馬達加斯加。這些人類被稱南島語族。
人類遷移到北美洲後經由北美平原、中美洲陸橋遷移到南美洲。最後到達火地島為止。
現代幾個國家科學家通過基因檢測手段，也部分證實人類起源於同一群體。
目前人類起源研究最有力的學科是新近產生的分子人類學。由於人類細胞中的Y染色體與粒線體都是通過直系親屬直接遺傳下來的，其間只有發生很小的變動。所以通過分析Y染色體與粒線體出現的分部與時間，就可以比較可靠的推出人類起源於人類遷移的路線。
In paleoanthropology, the recent single-origin hypothesis (RSOH, or Out-of-Africa model, or Replacement Hypothesis) is one of two accounts of the origin of anatomically modern humans, Homo sapiens. According to the RSOH, anatomically modern humans evolved in Africa between 200,000 and 100,000 years ago, with members of one branch leaving Africa between 55,000 and 60,000 years ago.[1] These emigrants spread to the rest of the world, replacing (and not interbreeding with) other Homo species already there, such as Neanderthals and Homo erectus.[2] The hypothesis is derived from research in several disciplines, chiefly genetics, archaeology and linguistics.
Currently available genetic and archaeological evidence is generally interpreted as supportive of a recent single origin of modern humans in East Africa.[3] The alternative theory is the multiregional hypothesis, including the Hybrid-origin theory.
Charles Darwin was one of the first to suggest that all humans had a common ancestor who lived in Africa. In the Descent of Man he writes:
| “ | In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere.[4] | ” |
The prediction was highly insightful because at the time, in 1871, there were hardly any human fossils of ancient hominids available. Almost fifty years later Darwin was vindicated, as anthropologists began finding numerous fossils of ancient hominids all over Africa (List of hominina fossils).
Homo habilis evolved in Africa 2 million years ago and is considered the first species of the genus homo. A descendent of Homo habilis known as Homo erectus or "upright man" is thought to be the first hominid to migrate out of Africa at least 1.5 million years ago. Erectus is believed to have left Africa during the warm periods between ice ages. An occasional phenomenon known as the Sahara pump theory, during which the Sahara desert receives significant rainfall, allows African flora and African fauna to penetrate the otherwise arid Middle East. It is believed that during one such period some Homo erectus migrated out to ultimately spread all over Europe and Asia and dominate the world for the next 1 million years. Fossils of homo erectus include Peking man from China and Java man from Indonesia.
Then, following a severe ice age 350,000 years ago, another large brained hominid, Homo heidelbergensis appeared on the African stage. Some of these hominids migrated to Europe and evolved into the Neanderthals. The Neanderthals occupied Europe until approximately 30,000 years ago when they became extinct. Some scientists propose that the Neanderthals were displaced and possibly wiped out by encroaching modern humans. While some researchers have found evidence which suggests that neanderthalensis had vocal capabilities similar to, or possibly exceeding that of, modern humans,[5] others conclude that although they may have possessed some form of speech, their phonetic abilities were limited relative to anatomically modern Homo sapiens from the same time period. Furthermore, evidence that Neanderthal tool culture was simple and relatively static suggests that Neanderthal language was less developed than that of modern humans and that this might have played a role in their demise. Stone technology remained relatively unchanged and unsophisticated for millions of years during the periods of erectus and the Neanderthals.[6]
Scientists believe modern humans first appeared in Africa less than 200,000 years ago. One of the reasons they believe this is that the oldest known remains of modern humans have been found in Africa and nowhere else. The Omo remains found near the Omo river in Ethiopia have been dated to 130,000 - 195,000 years ago and are the oldest fossil evidence of anatomically modern humans.
Humans did attempt on one occasion to leave Africa through the Middle East. Fossils of modern humans were found in a cave in Israel at Qafzeh and have been dated to 100,000 years ago. However these humans seem to have either gone extinct or retreated back to Africa 80,000 - 70,000 years ago, possibly replaced by south bound Neanderthals escaping the colder regions of ice age Europe.
All other fossils of fully modern humans outside of Africa have been dated to more recent times. The next oldest fossil of modern humans outside of Africa are those of Mungo Man found in Australia and have been dated to about 42,000 years ago.[7]
Though fossil remains of modern humans appear about 200,000 years ago, significant changes in technology do not appear until much later. Early humans apparently continued to use the same technology of the Neanderthals. Beginning about 100,000 years ago evidence of more sophisticated technology and artwork begins to emerge and by 50,000 years ago fully modern behaviour becomes more prominent. By this time the ritual burying of the dead is noted. Stone tools show regular patterns that are reproduced or duplicated with more precision. Tools made of bone and antler appear for the first time.[8][9] These new changes are suggestive of more advanced behaviour and scientists attribute these changes to the development of language. The new stone tool types have been described as being distinctly differentiated from each other as if each tool had a specific name. This period is referred to as the Upper paleolithic. For the first time in the fossil record evidence of fishing indisputably appears in Africa at 50,000 years ago. Homo erectus and the Neanderthals lived alongside oceans, rivers and lakes but never ate fish. Archaeological coastal sites that are dated to before 50,000 years contain no fish bones whereas those dated to after 50,000 do contain fish bones. This also serves as evidence for significant change in human behaviour at the 50,000 year mark.[10]
Cultural universals are the key elements shared by all groups of people throughout the history of man. Examples of elements that may be considered cultural universals are language, religion, art, music, marriage, gender roles, the incest taboo, myth, cooking, games, and jokes. These traits distinguish homo sapiens from other species. David Buller hypothesizes that some cultural universals may in fact be cultural homologies that originate from a common human ancestry.[11]Nicholas Wade writes:
There is considerable debate regarding when modern human language first came into existence. Much of the debate centers on whether modern language arose suddenly with anatomically modern humans or whether language developed gradually over millions of years with all archaic hominids. Those in favor of the "sudden occurrence" of language argue that the first indisputable signs of symbolism such as art, which are associated with language, occur in the fossil record 50,000 BP, and become significantly more abundant thereafter. They contend that language was a necessary prerequisite for modern humans to leave Africa and reach continents such as Australia, that had never before been populated by Archaic hominids. Since all these major historic events appear to take place around the 50,000 year mark, scholars believe this is when language suddenly arose, with some suggesting that it may have required some biological change such as a mutation affecting the brain.
Other schools of thought disagree with the sudden emergence of language. They argue that since only a few materials such as bone and stone fossilize, the lives of archaic hominids may have involved the use of several materials that do not fossilize, such as wood or bark. Hence it would be impossible to concretely ascribe a date to the first symbolism. In addition a few fossils that appear to be symbolic have been controversially dated to much earlier than 50,000 BP. These include the Katanda bone points from the Congo, dated to 100,000 years ago and engravings found on red ochre dated to 75,000 years ago from Blombos cave in South Africa. This would indicate that language may have arisen much earlier. However these findings are disputed with some arguing that they are simply anomalies in the fossil record.
Since the human line branched off from the common ancestor shared with chimpanzees six million years ago, the human vocal tract has been evolving. Hence some scholars argue that it must have been evolving for a reason. If the Neanderthals possessed a near modern if not fully modern vocal tract, then it would only make sense that it must have evolved for them to use some sort of speech. However critics once again point to the Neanderthal stone tool kit, that remained relatively unchanged and unsophisticated from millions of years before.
According to this hypothesis a small group of humans living in East Africa migrated north east, possibly searching for food or escaping climate changes, crossing the Red Sea and in the process going on to populate the rest of the world. Around 50,000 years ago the world was entering the last ice age and sea levels were much lower as water was trapped in the polar ice caps. Today at the Gate of Grief the Red Sea is about 12 miles (20 kilometres) wide but 50,000 years ago it was much narrower and sea levels were 70 meters lower. Though the straits were never completely closed, there may have been islands in between which could be reached using simple rafts. Shell middens 125,000 years old have been found in Eritrea indicating the diet of early humans was sea food obtained by beachcombing. This is perceived to be evidence that humans may have crossed the Red Sea in search of new food sources available on uninhabited beaches.
Genetic evidence points to a single exodus of a small group of people with some estimating as few as 150 people.[citation needed] From this small group descended all non-African people. Once in Asia they spread generation by generation around the coast of Arabia and Iran until they reached India which appears to be the first important settling point. Once in India the populations split, One group ventured inland northwest towards Europe and would eventually go on to displace the Neanderthals. The other group headed along the southeast coast of Asia reaching Australia between 70,000 and 30,000 years ago, with most estimates placing it as occurring about 46,000 to 41,000 years ago.
During that time the sea levels were much lower and most of Maritime Southeast Asia was one land mass known as the lost continent of Sunda. The settlers would have continued on the coastal route southeast until they reached the channel between Sunda and Sahul, the continental land mass that comprised present day Australia and New Guinea. This channel is also known as the Wallace Line. The Channel was 90 km wide, indicating that settlers must have had knowledge of seafaring skills in order to reach Australia. Archaic humans such as Homo erectus never reached Australia.
If these dates are correct it would mean that Australia was populated before Europe by up to 10,000 years. This is possibly because humans avoided the colder regions of the North favoring the warmer tropical regions, possibly lacking technology to survive the cold. Another piece of evidence favoring human occupation in Australia is that by 46,000 years ago all large mammals weighing more than 100 kg had suddenly become extinct. The new settlers are the likely suspects of this extinction. Many of the animals may have been accustomed to living without predators and become docile and vulnerable to attack.
While some settlers crossed into Australia others may have continued eastwards along the coast of Sunda eventually turning northeast to China and finally reaching Japan, leaving a trail of coastal settlements. This coastal migration leaves its trail in the mitochondrial haplogroups descended from haplogroup M, and in Y-chromosome haplogroup C. Thereafter it may have become necessary to venture inland possibly bringing modern humans into contact with archaics such as erectus. Recent genetic studies suggest that Australia and New Guinea were populated by one single migration from Asia as opposed to several waves. The land bridge separating New Guinea and Australia became submerged approximately 8,000 years ago, thus isolating the respective populations of the two land masses[13][14].
Europe is thought to have been colonized by northwest bound migrants from India and the Middle East. The expansion from India is thought to have begun 45,000 years ago and may have taken up to 15,000 years for Europe to be fully colonized.[15][16] During this time the Neanderthals were slowly being displaced. Because it took so long for Europe to be overrun, it appears that humans and Neanderthals may have been constantly competing for territory. The Neanderthals were larger and had a more robust or heavy built frame which may suggest that they were physically stronger than modern homo sapiens. Having lived in Europe for 200,000 years they would have been better adapted to the cold weather. The Anatomically Modern Humans, known as the Cro-Magnons, however, with superior technology and language would eventually completely displace the Neanderthals whose last refuge was in the Iberian peninsula. After about 30,000 years ago the fossil record of the Neanderthals ends, indicating that they had become extinct. The last known population lived around a cave system on the remote south facing coast of Gibraltar from 30,000 to 24,000 years ago.
Multiregionalists have long believed that Europeans were descended from Neanderthals and not from humans from Africa. Others believed the Neanderthals had interbred with modern humans. In 1997 researchers managed to extract mitochondrial DNA from a 40,000 year old specimen of a Neanderthal. On comparison with human DNA, its sequences differed significantly, indicating that based on the mitochondrial DNA, modern Europeans are not descended from the Neanderthals and that no interbreeding took place.[17] Some scientists continue to search autosomal DNA for traces of Neanderthal admixture.[18] A few alleles of some autosomal genes such as the H2 allele of the MAPT gene have been suggested, since they were only found among Europeans. However in the absence of autosomal DNA from a Neanderthal, the scientists conclude that this hypothesis is entirely speculative[19].
Some archaeologists doubt that Neanderthals and homo sapiens were interfertile. This is because Neanderthals and Europeans shared the same habitat for up to 20,000 years yet no undisputed skeletal fossils have been found so far that show intermediate properties between the two hominids[20].
The Americas were occupied by Asian people who crossed from Siberia into Alaska. At the time sea levels were lower and a land bridge of the lost continent of Beringia connected North America to Eurasia. It is likely they used the southern route that may have been much warmer.
There is considerable controversy over when the Americas were first colonized and how many migrations there were. Controversial findings in Chile at Monte Verde may indicate a human presence in the Americas by up to 33,000 years ago. The oldest indisputable evidence of human presence in the Americas are, however, findings related to the Clovis culture, which have been dated to about 11,000 years ago. The findings of Clovis points indicate the early settlers hunted large animals. About the same time as the arrival of the clovis culture many large animals such as Mammoths became extinct (as in Australia, possibly due to hunting).
Linguist Joseph Greenberg controversially classified American languages into three major families. The Eskimo-Aleut spoken by the Inuit peoples. The Na-Dené are 32 languages spoken only in North America by the Apache, Navajo and tribes in Alaska and Canada. Finally Amerind languages comprise more than 500 languages spoken in North and South America. Greenberg suggested that these three languages families represented three separate migrations that filled the Americas in the order they arrived.
Up until recently the only way of learning about ancient ancestors was through old fossils and stone tools. As we travel further back in time fossils become more rare. Of the billions of people who lived before the invention of agriculture only the fossilized remains of a few hundred have been found. In the absence of fossils, human DNA that transmits genetic information from one generation to the next has proved to be a valuable tool in recording the evolution of the human species.
Two pieces of the human genome are particularly useful in deciphering human history. One is the Mitochondrial DNA and the other is the Y chromosome. These are the only two parts of the genome that are not shuffled about by the evolutionary mechanisms designed to generate diversity with each generation. Hence the Mitochondrial DNA and the Y chromosome are passed down generation to generation intact. All 6.5 billion people alive today have inherited the same Mitochondria from one woman who lived in Africa about 150,000 years ago; she has been named Mitochondrial Eve. All men today have inherited their Y chromosomes from a man who lived 60,000 years ago, probably in Africa. He has been named Y-chromosomal Adam.
The Human Genome is comprised of 3.1 billion base DNA base pairs packed in the chromosomes located in the Nucleus. Each person has 23 pairs of chromosomes. In each pair one chromosome is descended from the sperm cell of the father and the other chromosome is descended from the mother's egg. When an adult organism begins to produce sperm or egg cells these two chromosome line up against each other and exchange pieces of DNA with each other in a process known as chromosomal crossover.
Mitochondria are components found in the cell outside the nucleus that provide energy to the cell. They are believed to have originally been free bacteria that became incorporated into the cells of organisms billions of years ago. This is because the mitochondria have their own strand of DNA in a loop similar to those of bacteria. As the mitochondria are located outside the nucleus they do not participate in the shuffling of DNA that occurs during reproduction. When the sperm fuses with an egg cell during fertilization, the sperm's mitochondria are destroyed, leaving only the egg cell's mitochondria in the new fertilized zygote. This process only passes down the mother's mitochondrial DNA (mtDNA) to the next generation. All people have their mother's mtDNA but not their father's. Thus, a family tree of humanity based on the maternal line can be drawn, whereby the tree eventually coalesces on one female, and that person is Mitochondrial Eve.
The DNA in mitochondria is relatively short with only 16,569 base pairs. Thus it is much easier to study than the rest of the genome. When a woman's mitochondria are copied and packed into an egg cell, the DNA is almost always the same. However, every once in a while a mutation takes place which alters the sequence of the DNA strand. If Mitochondrial Eve had two daughters, one of whom happened to have a mutation in her Mitochondrial DNA, then all the women alive today descended from that daughter would share that mutation. All the women descended from the other daughter would not. Thus mutations in mtDNA are useful in determining lineages and migratory patterns.
The pair of sex chromosomes are unlike the other 22 pairs of chromosomes. The X and Y chromosomes do not exchange segments of their DNA (except at the very tips). All other pairs of chromosomes are virtually identical in size and number of genes and hence compatible to exchange segments. The Y chromosome is significantly smaller than the X and thus incompatible for large scale shuffling. This process is necessary to ensure that the Y's most important gene, the one responsible for making a person male, is not transferred to the X chromosome, which is responsible for making a person female.
It follows that the Y chromosome is passed down largely intact from fathers to sons through the generations. Just as with mtDNA, mutations in the Y-chromosome make a fork in the family tree and can be used to study lineages. The genome of the Y chromosome is much larger (58 million base pairs) than that of mtDNA and initially mutations in it were much harder to find. More recently the mapping of the Y has been completed. All men today have inherted the Y-chromosome of Y-chromosomal Adam who may have lived 60,000 years ago in Africa. Comparing the profile of the Y chromosome with that of the mtDNA of a population may give useful hints about differences in ancient migratory patterns of men and women.
The molecular clock is a technique in genetics used to estimate when populations diverged. When comparing the mtDNA sequences of two populations, researchers can target mutations that are present in one population and absent in the other. The more mutations that differentiate the sequences, the longer the populations have been separated. The assumption is that mutations are random events that occur at a steady rate; for example, in humans it is sometimes estimated that a mutation takes place every 10,000 years. Thus, if mtDNA sequences of two populations differ by 5 nucleotides, it can be inferred that the two populations split from a common ancestral population 50,000 years ago.[21] The clock can be calibrated by using a references pair of groups of living species whose date of speciation was already known from the fossil record.
The molecular clock is a statistical analysis based on many assumptions and hence its accuracy is sometimes questioned. However, studies do show some consistency with fossil records. For example, Mitochondrial Eve is calculated to have lived about 150,000 years ago. This is consistent with the emergence of anatomically modern humans based on fossil evidence. Furthermore, the dates calculated based on the Y-chromosome are in general agreement with those for mitochondrial DNA. This is a useful comparison because Y and mtDNA are inherited independently and they have different mutation rates.
In formulating the single origin hypothesis, scientists focussed their research on many indigenous groups. This is because these groups have lived in the same location for thousands of years. Since many indigenous groups have remained relatively isolated from the later immigrant populations they live with, their genetics may be the least influenced by the effects of long distance migration. Their genetic makeup would thus be the best available representation of the early settlers in a region.
Language isolates are languages that have no known historical or linguistic relationship to any other languages. They are useful to anthropologists in identifying groups that may have a more distinctive history. The Basque language spoken in Spain and France has confounded linguists because it is one of the only languages in Europe that doesn't belong to the Indo-European language family. The language of the Ainu in Japan is also another isolate. So is Burushaski, the language spoken near the Pamirs in the Himalayas. The Khoisan languages are also of interest because of the use of the click consonant. The Hadza language of Tanzania also uses the click consonant but appears to be unrelated to the Khoisan languages. There are several isolates among the indigenous languages of New Guinea and Australia.
Of particular interest are the so called Negritos who are the indigenous people of the Andaman Islands. It is believed that they were isolated on the islands perhaps thousands or even tens of thousands of years ago due to rising sea levels. They were once thought to be related to African pygmies because of their short stature, however they are genetically more linked to the surrounding Asian populations . Their language is also unique and linguists have all but failed to find a connection to any of the world's major language families. A related group, the Sentinelese, have resisted all attempts to be contacted and almost nothing is known about them. This suggests that these groups have been genetically isolated for long periods and may have been part of the first group of people to settle in Asia.[22]
When researchers first began studying the mtDNA peoples around the world in 1987 they found that the greatest diversity of lineages was found in Africa. Of the 33 maternal clans of the world, 13 were in Africa. Though Africa had 13% of the worlds population it had 40% of the world's deeper mitochondrial lineages. This indicated that Africa had more time to accumulate mutations than the rest of the world. As a rule of thumb for any species, the region of greatest diversity is very likely the region of origin.
Scientists were then able to construct the genetic relationships between the various mitochondrial haplogroups and build a family tree. One by one they found the African and also all non-African mitochondrial lineages converged on a single root, and this mitochondrial ancestor was named Mitochondrial Eve. They then identified a single African mitochondrial lineage, haplogroup L3e, that was the single root for all the mitochondrial lineages found outside Africa. This evidence indicated that the human family arose as one single genetic line in Africa within the last 200,000 years and not as multiple lineages in separate locations.
Eve was not the only woman alive at the time but only her line of descent remains unbroken today in all humans. Some scientists believe that the human family faced near extinction in the last 100,000 years due to some catastrophic event (see Toba catastrophe theory). The human population may have dwindled to as few as 2,000 people, causing the lineages of other women to die out leaving only those of Eve's to dominate. This process has been described as the founder effect.
It is widely accepted that humans first arose in Africa and later colonized Eurasia and the rest of the world. However, the timing of the exit out of Africa and the routes taken remain controversial. Owing to the time frame, the patterns of migration are very complex and scientists are likely to continue making revisions and adjustments to existing theories as further studies yield new information.
The first lineage to branch off from Eve is L1. This haplogroup is found in high proportions among the San and the Mbuti people.[23] These groups branched off early in human history and have remained relatively isolated genetically since. Haplogroups L2 and L3 are descendents of L1 and are largely confined to Africa. The macro haplogroups M and N, which are the lineages of the rest of the world outside Africa, descended from L3.
Some scientists believe that only a few people left Africa in a single migration that went on to populate the rest of the world. It has been estimated that from a population of 2,000 - 5,000 in Africa, only a small group of possibly 150 people crossed the Red Sea. This is because, of all the lineages present in Africa, only the daughters of one lineage, L3, are found outside Africa. Had there been several migrations one would expect more than one African lineage outside Africa. L3's daughters, the M and N lineages, are found in very low frequencies in Africa and appear to be recent arrivals. A possible explanation is that these mutations occurred in East Africa shortly before the exodus and by the founder effect became the dominant haplogroups after the exodus from Africa. Alternatively, the mutations may have arisen shortly after the exodus from Africa.
Other scientists propose that there were two migrations out of Africa, one across the Red Sea travelling along the coastal regions to India, which would be represented by Haplogroup M. Another group of migrants with Haplogroup N followed the Nile from East Africa, heading northwards and crossing into Asia through the Sinai. This group then branched in several directions, some moving into Europe and others heading east into Asia. This hypothesis attempts to explain why Haplogroup N is predominant in Europe and why Haplogroup M is absent in Europe.[24]
The group that crossed the Red Sea travelled along the coastal route around the coast of Arabia and Iran until reaching India, which appears to be the first major settling point. M is found in high frequencies along the southern coastal regions of Pakistan and India and it has the greatest diversity in India, indicating that it is here where the mutation may have occurred.[25] 60% of the Indian population belong to Haplogroup M. The indigenous people of the Andaman Islands also belong to the M lineage. The Andamanese are thought to be offshoots of some of the earliest inhabitants in Asia because of their long isolation from mainland Asia. They are evidence of the coastal route of early settlers that extends from India along the coasts of Thailand and Indonesia all the way to Papua New Guinea. Since M is found in high frequencies in highlanders from New Guinea as well, and both the Andamanese and New Guineans have dark skin and frizzy hair typically found in Africa, some scientists believe they are all part of the same wave of migrants who departed across the Red Sea. Others suggest that their physical resemblance to Africans is more likely to be an example of convergent evolution.[26][27][28]
From Saudi Arabia to India the proportion of haplogroup M increases eastwards: in eastern India, M outnumbers N by a ratio of 3:1. However, crossing over into East Asia, Haplogroup N reappears as the dominant lineage. M is predominant in South East Asia but amongst Indigenous Australians N reemerges as the more common lineage. This discontinuous distribution of Haplogroup N from Europe to Australia has confounded scientists attempting to trace migratory routes.[29]
The descendents of Haplogroups M and N are both found in the Americas.
There is considerable speculation on the physical appearance of ancient homo sapiens during the period of Mitochondrial Eve and prior to exodus from Africa. The reason for this is that all variation in human physical appearance visible in today's people around the world is theorized by some scientists to have come from this small population in Africa.
Hairiness is the default state of most mammals, though a few have lost much of their hair for a variety of reasons. They include many aquatic mammals such as dolphins and hippopotami, the naked mole rat and humans. Most non-human primates have lightly pigmented skin covered by fur. Scientists believe that early protohominids resembled our closest relative, the chimpanzee, with white skin covered by dark hair. The hominids began to walk upright and left the shade of the trees for the open savannah and therefore required a more efficient cooling system. The brain uses significant amounts of energy but is very sensitive to heat, so the increased brain power of the early hominids also required a finer thermoregulatory system. As a result humans evolved more sweat glands, especially on the face, which required the loss of hair for more effective evaporation. Sexual selection by a preference for naked skin may have played a secondary role as well. Though naked skin is advantageous for thermoregulation, it exposes the epidermis to destructive levels of UV radiation that can cause sunburn, skin cancer and birth defects resulting from the destruction of the essential vitamin B folate. To protect the epidermis natural selection favored increased levels of melanin in the skin. [30]
The general consensus among scholars is therefore that the first modern humans would have been dark skinned. When humans migrated to less sun intensive regions in the north, the dark skin that was adapted to blocking out much of the UV radiation in the tropics would block even the minimum amount of radiation required for cells under the skin to produce Vitamin D. This is essential for bone growth, as deficiencies in vitamin D cause rickets. Thus skin color would revert back to its default form present before the process of hair loss began, but this time without the hair. Whilst the timing of this change from dark to light skin has not yet been established it is possible that the early settlers of Europe and Asia were dark skinned.[31] Aside from skin color however, which despite the above could also arguably be included, the majority of apparent difference in human physical appearance around the world, or what may also be called racial features, can also be explained through the process of regional sexual selection of relatively recent evolutionary origin.[32]
The multi-regional hypothesis consists of several models of human evolution which all posit that the human races evolved from separate archaic humans over millions of years. The Multiregional theory is based largely on archaeological and fossil evidence. Proponents of the Multiregional theory argue that physical similarities between modern and archaic humans, such as the brow ridges and comparatively robust skeletons of some modern Europeans (as compared to Neanderthals), and the shovel-shaped incisors and other distinct craniofacial features noted in modern Chinese (as compared with Chinese homo erectus), could only be the result of genetic contributions from earlier lineages that evolved semi-independently. Opponents, however, cite the lack of DNA evidence supporting these theories.
There are several models of multiregionalism that depend largely on whether gene flow between the populations took place. Polygenism is a more extreme form multiregionalism in that it implies separate origins for the human races. Proponents include Carleton Coon who hypothesized that modern humans, Homo sapiens, arose five separate times from Homo erectus in five separate places. Their descendents are the major races of today.[33] Polygenists such as Arthur de Gobineau believed in the existence of pure races.
The hybrid-origin theory states that significant gene exchange did take place between widely divergent hominid species, or subspecies, that were geographically dispersed throughout Africa, Southeast Asia and the Indian subcontinent. According to this theory the resulting hybrid 'Homo sapiens sapiens', was superior to both its ancestors due to what is commonly termed hybrid vigour. They argue that very strong genetic similarities among all humans do not prove recent common ancestry, but rather reflect the interconnectedness of human populations around the world, resulting in relatively constant gene flow (Thorne and Wolpoff 1992).
Aspects of multiregionalism has been criticized as not being based on objective scientific observation. Some critics even argue that multiregionalism may be motivated by ethnocentrism and is meant to instill beliefs of purity of lineage.[34]
Multiregionalists have long claimed that modern Europeans are descended from the Neanderthals. In 1997, DNA testing performed on a Neanderthal skeleton showed modern humans and Neanderthals last shared a common ancestor between 500,000 and 800,000 years ago, and furthermore that all modern humans, from the ethnic Siberians to the !Kung people of Africa, are more closely related to each other than to the Neanderthals -- further evidence supporting the Out-of-Africa theory.
Another example is the case of Peking man, a fossil skull of homo erectus found in China dating to possibly 400,000 years. Some Paleoanthropoligists in China have asserted that the modern Chinese are descendents of earlier forms of humans such as Peking Man. However, Chinese geneticists performed microsatellite analysis on the Chinese population in 1998 and discovered genetic similarities with Africans, yielding the first evidence that the Chinese descended from Africa. [35] A recent study undertaken by Jin Li showed no inter-breeding between modern human immigrants to East Asia and Homo erectus, contradicting the Peking Man-origin hypothesis and affirming that the Chinese descended from Africans.[36][37] In 2001, Chinese geneticists analyzed Y chromosomes in Chinese people and concluded that all Chinese samples contained a mutated gene M168G which is a marker believed to have appeared in the last 79,000 years on a number of Africans.[35]
The fossil record also favors a single origin. This is because mainly in Africa is there a sensible progression of fossils over the last 3 million years that shows the various intermediate stages of evolution from the most archaic ancestors to modern man.
在古人類學中，多地起源說是兩種主要的人類起源的假說之一，另一種為單地起源說。不過1990年代以來在基因學上的證據較支持單地起源說。但仍有一定數量的學者支持多地起源說。
此名詞最早是1980年代由密西根大學教授沃波夫（Milford H. Wolpoff）所使用。該假說認為：在150萬年前人類的祖先（匠人：Homo ergaster，或直立人：Homo erectus）離開非洲後，便開始在世界各地獨自演化，包括尼安德塔人、北京人和爪哇人等，並適應當地的環境。根據沃波夫的說法，世界各地的人類同時平行演化成今天的現代人。不同地區的人類由於地理隔絕因此往不同的方向演化；但另一方面，雜交、取代和基因流動等其他複雜的因素使現代人往大約一致的方向演化。
最終，一些地方上人類的多樣性被取代消失，使得今日的現代人雖保有一些地方特徵，但共有更多的相似處。 ：
目錄[隱藏] |
1930年代德國人類學家魏敦瑞(Franz Weidenreich) 在研究北京人時認為，北京人和現代亞洲人有很多相似特徵。根據魏敦瑞的說法：人類的種族是由各地的古代直立人獨自演化為今天的智人；與此同時，基因流動發生在不同的人類之間。魏敦瑞認為：一般適應的基因(如智力和溝通能力)從世界的某處到其他地方流動較快，而地方適應的基因則流動較慢。
1960年代美國人類學家卡爾頓·庫恩(Carleton Coon) 便有類似多地起源說的理論。庫恩認為現代人是由五種不同的人類平行演化而來 (高加索人種、剛果人種、開普人種、蒙古人種和澳大利亞人種)。庫恩又認為一些種族比其他種族要早演化進入現代人的階段，導致一些人類的文明要進步於其他文明[1]。他認為：高加索人種和蒙古人種要優越於其他人種。[2] 該理論在1960年代中期非常不受歡迎，被認為有正當化種族隔離之嫌，庫恩因此被迫辭去美國形態人類學協會會長的職務。
Studies on past population bottlenecks that can be inferred from molecular data have led Multiregionalists to conclude that the recent single-origin hypothesis is untenable because there are no population size bottlenecks affecting all genes that are more recent than the one at the beginning of the species, some 2 million years ago. Multiregionalists claimed that the discovery of a possible hybrid Homo sapiens X neanderthalensis fossil child at the Abrigo do Lagar Velho rock-shelter site in Portugal in 1999 further supports the Multiregional hypothesis, by reflecting the inter-mixture of diverse human populations. Other archaeologists dispute this: "the analysis by Duarte et al. of the Lagar Velho child's skeleton is a brave and imaginative interpretation, of which it is unlikely that a majority of paleoanthropologists will consider proven." [1]
Proponents of the multiregional hypothesis point to a recent Australian study of an ancient Aboriginal skeleton known as Mungo Man. Genetic tests show the mitochondrial DNA of Mungo Man to be from a mtDNA lineage with no descendants today. Yet Mungo man is an anatomically modern human and has been dated to be at least 40,000 years old. These proponents interpret the study to mean that mtDNA does not reflect ancestry or divergence times, and this interpretation is supported by the discovery that the gene is subject to natural selection.
A recent, non-fossilized discovery of one metre-tall, small-brained (350 cc), Homo floresiensis, on the Indonesian island of Flores, might imply populations of Homo erectus survived very late, and gave rise to even later, physically dwarfed isolated "erectus" groups. However, this possibility does not address the Multiregional hypothesis, which is only about the human species, and the evidence is marred by the possibility that the single dwarf cranium found on Flores might have been pathological.
Proponents of the Hybrid-origin hypothesis point to the study Research on the X chromosome and interpret it to give genetic evidence for inter-breeding between Humans and other hominids.
Besides Milford H. Wolpoff, paleoanthropologists most closely associated with the multiregional hypothesis include James Ahern, James Calcagno[2], Rachel Caspari, David Frayer, Mica Glanz, John Hawks[3], Andrew Kramer, Sang-Hee Lee, Alan Mann, Janet Monge, Jakov Radovcic, Valeri Alexeev, Karen Rosenberg, Mary Russell, Lynne Schepartz, Fred Smith, Alan Thorne, Adam Van Arsdale, Bernard Vandermeersch.
有人認為：多地起源說不是基於客觀的科學研究，而是基於種族優越感，以灌輸人種間血統純粹性的教育[3]。 但事實上，現代支持這一學說的學者特別是中國學者多無種族主義思想，他們能提出科學的證據（見上面的「現代支持這一理論的證據」），並且更多地是在討論體質特徵、遺傳基因、文化形態有巨大差別的現代人作為一個單一物種究竟是如何產生的，而不是在爭論種族的優劣。
多地起源說支持者宣稱現代歐洲人是古代尼安德塔人的後代。在1997年，DNA測試分析了尼安德塔人的頭骨，指出現代人與尼安德塔人的共同祖先至少是在50~80萬年前的古代猿人；此外，所有的現代人種間的差異均比與尼安德塔人的差異為小，更加說明了現代人與尼安德塔人是不同的物種。
經過中國考古學家的不懈努力，在中國已經發現了800萬年前的祿豐古猿，黃萬波發現了200萬年前早期直立人巫山人，170萬年前的元謀人，115萬年前的藍田人，50萬年前的北京人和鄖縣人，30萬年前的安徽和縣人和南京湯山人，10萬-20萬年前的早期智人遼寧金牛山人、陝西大荔人、安徽含銀山人、山西許家窯人、丁村人、廣東馬壩人、湖北長陽人，1萬-4萬年前的晚期智人如廣西柳江人、內蒙古河套人、北京山頂洞人、雲南麗江人、四川資陽人、貴州穿洞人、陝西黃洞人等等。雖然存在兩個缺環：一個是沒有發現更早的直立人化石和人類近祖南方古猿化石，另一個是沒有發現距今5-10萬年的智人化石，但這仍是一個近乎完整的人類進化系統，除了非洲外，中國也是大致上連續不斷的古人類化石發現地，因此，有相當數量的中國古人類學家認為現代中國人是獨立起源於中國的。
還有中國學者對古人類體質特徵和舊石器時代文化進行了系統研究後指出，儘管存在外來的基因交流和文化交流，中國現代智人形成過程中連續進化仍是主流。中國從古人類到現代人的體質特徵是一脈相承的，並未出現被非洲古人類取代從而造成的體質上的改變，北京直立人（過去稱北京猿人）身上的一些特徵在現代華北人身上仍有反映，現代中國人並沒有出現非洲人的體質特徵。中國的舊石器時代文化、新石器時代文化、原始社會文化等等都是一脈相承，沒有出現斷層或大的改變。[4]這些現象也促使多數中國學者相信中國人自生說。
這一理論與1990年代的基因研究結論相矛盾。
1990年代，中國基因學者陳竺和金力的研究指出現代亞洲人與古代亞洲直立人之間並沒有直接關係存在；現代的中國人是約5萬年前由非洲遷徙而來的人類後代。[5]
這一理論難以解釋：如果中國古人類真的被完全取代，為什麼中國古人類體質及文化特徵上存在連續性而沒有斷層或大的改變？
為了解決這兩種學說的矛盾，一些中國古人類學家如吳新智等提出了「連續進化附帶雜交」的中國人起源模型。此外，美國北伊利諾伊大學的遺傳學家史密斯也提出了一個折中的同化模型，認為從非洲出發的擴張和各人群之間的遺傳交流在人類進化過程中都起過重要作用。
這些人認為：西歐和中國人的起源模式有區別，東南亞、澳洲、美洲的模式及它們與非洲的關係也不盡相同，是完全取代、連續進化還是融合同化，不能用同一種模式概括所有現代人的起源，不同模式在各地人類起源過程中的作用並不相同。[6]
3個分類: 自2007年11月正在翻譯的條目 | 人類演化 | 考古學
In paleoanthropology, the multiregional hypothesis is one of two accounts of the origin of anatomically modern humans, Homo sapiens. The other theory is the recent single-origin hypothesis (or Out-of-Africa model). While Out of Africa has received much support over the last decade, there do remain several prominent multiregionalists.
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Because of the scarcity of fossils and the discovery of important new finds every few years, researchers disagree about the details and sometimes even basic elements of human evolutionary history. While they have revised this history several times over the last decades, researchers currently agree that the oldest named species of the genus Homo, Homo habilis, evolved in Africa around two million years ago, and that members of the genus migrated out of Africa somewhat later, at least 1.5 million years ago. The descendants of these ancient migrants, which probably included Homo erectus, have become known through fossils uncovered far from Africa, such as those of "Peking man" and "Java man". Homo neanderthalensis is also considered a descendant of early migrants.
The multiregional hypothesis for the human species holds that the evolution of humanity throughout the Pleistocene has been within a single widespread human species, Homo sapiens, in response to the normal forces of evolution: selection, mutation, genetic drift, and gene flow.
The term "multiregional hypothesis" was first coined in the early 1980s by Milford H. Wolpoff and a group of associates as an explanation for the apparent similarities of the remains from the Homo erectus and Homo sapiens inhabiting the same region. This phenomenon was termed regional continuity and baffled the scientists at first. These scientists explained the apparent regional continuity by claiming Homo erectus and Homo sapiens were the same species and there had been just enough interbreeding to cause an overall global development towards the latter, but without stamping out the regional adaptation that had been developed by the former. Such a delicate balance seemed unlikely and puzzled the anthropologists.
The Multiregional Hypothesis has its origin in the work of Franz Weidenreich in the 1930s. At that time, Weidenreich originated the "Weidenreich Theory of Human Evolution" based on his examination of Peking Man. Weidenreich was an anatomist and observed numerous anatomical characteristics that Peking Man had in common with modern Asians. The Weidenreich Theory stated that human races have evolved independently in the Old World from Homo erectus to Homo sapiens sapiens, while at the same time there was gene flow between the various populations. According to the theory proposed by Weidenreich, genes that were generally adaptive (such as those for intelligence) flowed relatively rapidly from one part of the world to the other, while those that were locally adaptive, would not. This is the direct opposite to theories of human evolution that have been popularized in the press with one superior race (e.g. Modern Humans) displacing other races (e.g. Neanderthals). A vocal proponent of the Weidenreich theory was Carleton Coon.
Eventually, Milford H. Wolpoff proposed an explanation based on clinal variation that would allow for the necessary balance. This was the multiregional hypothesis. It theorizes that Homo erectus, Neanderthals, Homo sapiens and other humans were a single species. This species arose in Africa two million years ago as Homo erectus and then spread out over the world, developing adaptations to regional conditions.
For periods of time some populations became isolated, developing in a different direction. But through a complicated process involving continuous interbreeding, replacement, genetic drift and other vehicles of evolution, adaptations that were an advantage anywhere on earth would spread, keeping the development of the species in the same overall direction, while maintaining adaptations to regional factors.
Eventually, the more unusual local varieties of the species would have disappeared in favor of modern humans while retaining some regional adaptations, but also with many common features.
Multiregional evolution contrasts with the "recent single origin hypothesis (RSOH)." According to that theory, human evolution was a consequence of many cases of species replacement, as newer species replaced older ones across the human range. Modern human origins, according to the RSOH, is the most recent example of species replacement.
An older theory is Polygenic evolution, a multiple origins theory in which the different human populations or races had independent origins and evolved in isolation from each other. Held by many scholars of the 19th century such as Haeckel and Klaatsch, and even some of the 20th, such as Carleton S. Coon, it is biologically impossible since all populations of a species must have the same, single origin. Polygenism is sometimes mistaken for Multiregional evolution, because they are both hypotheses of evolution within a single species. However, Polygenic evolution depends on isolation of populations while Multiregional evolution requires population interactions and interbreeding so that genetic changes can spread throughout the human range, especially when they are promoted by natural selection. According to the Multiregional hypothesis, geographic differences between human populations are the results of climatic variation, isolation by distance, and historical accidents (genetic drift).
Studies on past population bottlenecks that can be inferred from molecular data have led Multiregionalists to conclude that the recent single-origin hypothesis is untenable because there are no population size bottlenecks affecting all genes that are more recent than the one at the beginning of the species, some 2 million years ago. Multiregionalists claimed that the discovery of a possible hybrid Homo sapiens X neanderthalensis fossil child at the Abrigo do Lagar Velho rock-shelter site in Portugal in 1999 further supports the Multiregional hypothesis, by reflecting the inter-mixture of diverse human populations. Other archaeologists dispute this: "the analysis by Duarte et al. of the Lagar Velho child's skeleton is a brave and imaginative interpretation, of which it is unlikely that a majority of paleoanthropologists will consider proven." [1]
Proponents of the multiregional hypothesis point to a recent Australian study of an ancient Aboriginal skeleton known as Mungo Man. Genetic tests show the mitochondrial DNA of Mungo Man to be from a mtDNA lineage with no descendants today. Yet Mungo man is an anatomically modern human and has been dated to be at least 40,000 years old. These proponents interpret the study to mean that mtDNA does not reflect ancestry or divergence times, and this interpretation is supported by the discovery that the gene is subject to natural selection.
A recent, non-fossilized discovery of one metre-tall, small-brained (350 cc), Homo floresiensis, on the Indonesian island of Flores, might imply populations of Homo erectus survived very late, and gave rise to even later, physically dwarfed isolated "erectus" groups. However, this possibility does not address the Multiregional hypothesis, which is only about the human species, and the evidence is marred by the possibility that the single dwarf cranium found on Flores might have been pathological.
Proponents of the Hybrid-origin hypothesis point to the study Research on the X chromosome and interpret it to give genetic evidence for inter-breeding between Humans and other hominids.
Besides Milford H. Wolpoff, paleoanthropologists most closely associated with the multiregional hypothesis include James Ahern, James Calcagno[2], Rachel Caspari, David Frayer, Mica Glanz, John Hawks[3], Andrew Kramer, Sang-Hee Lee, Alan Mann, Janet Monge, Jakov Radovcic, Valeri Alexeev, Karen Rosenberg, Mary Russell, Lynne Schepartz, Fred Smith, Alan Thorne, Adam Van Arsdale, Bernard Vandermeersch.
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![更新世時的人種分布，根據Carleton S. Coon [1].](http://zh.wikipedia.org/w/index.php?title=Image:Carleton_Coon_races_Pleistocene.PNG&variant=zh-tw)
![更新世後的人種分布，根據Carleton S. Coon [2].](http://zh.wikipedia.org/w/index.php?title=Image:Carleton_Coon_races_after_Pleistocene.PNG&variant=zh-tw)
![[5]](http://www.corante.com/loom/img/Templeton%20tree%20600.jpg){kind=link}