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Saturday, July 10, 2010

Major Climate Change Occurred 5,200 Years Ago

Major Climate Change Occurred 5,200 Years Ago: Evidence Suggests That History Could Repeat Itself

ScienceDaily (Dec. 24, 2004) — COLUMBUS, Ohio -- Glaciologist Lonnie Thompson worries that he may have found clues that show history repeating itself, and if he is right, the result could have important implications to modern society.
Thompson has spent his career trekking to the far corners of the world to find remote ice fields and then bring back cores drilled from their centers. Within those cores are the records of ancient climate from across the globe.
From the mountains of data drawn by analyzing countless ice cores, and a meticulous review of sometimes obscure historic records, Thompson and his research team at Ohio State University are convinced that the global climate has changed dramatically.
But more importantly, they believe it has happened at least once before, and the results were nearly catastrophic to emerging cultures at the time. He outlined his interpretations and fears today at the annual meeting of the American Geophysical Union in San Francisco.
A professor of geological sciences at Ohio State and a researcher with the Byrd Polar Research Center, Thompson points to markers in numerous records suggesting that the climate was altered suddenly some 5,200 years ago with severe impacts.
He points to perfectly preserved plants he discovered that recently emerged from the Quelccaya ice cap in the Peruvian Andes as that glacier retreats. This monstrous glacier, some 551 feet (168 meters) deep, has shown an exponentially increasing rate of retreat since his first observations in 1963.
The plants were carbon-dated to determine their age and tests indicated they had been buried by the ice for perhaps 5,200 years. That suggests that somehow, the climate had shifted suddenly and severely to capture the plants and preserve them until now.
In 1991, hikers found the preserved body of a man trapped in an Alpine glacier and freed as it retreated. Later tests showed that the human – dubbed Oetzi – became trapped and died around 5,200 years ago.
Thompson points to a study of tree rings from Ireland and England that span a period of 7,000 years. The point in that record when the tree rings were narrowest – suggesting the driest period experienced by the trees – was approximately 5,200 years ago.
He points to ice core records showing the ratio of two oxygen isotopes retrieved from the ice fields atop Africa’s Mount Kilimanjaro. A proxy for atmospheric temperature at the time snow fell, the records are at their lowest 5,200 years before now.
He lists the shift by the Sahara Desert from a habitable region to a barren desert; major changes in plant pollen uncovered from lakebed cores in South America, and the record lowest levels of methane retrieved from ice cores from Greenland and Antarctica and all occurred at the same time – 5,200 years ago.
“Something happened back at this time and it was monumental,” Thompson said. “But it didn’t seem monumental to humans then because there were only approximately 250 million people occupying the planet, compared to the 6.4 billion we now have.
“The evidence clearly points back to this point in history and to some event that occurred. It also points to similar changes occurring in today’s climate as well,” he said.
“To me, these are things we really need to be concerned about.” The impact of a climate change of that magnitude on a modern world would be tremendous, he said. Seventy percent of the population lives in the world’s tropics and major climate changes would directly impact most of them.
Thompson believes that the 5,200-year old event may have been caused by a dramatic fluctuation in solar energy reaching the earth. Scientists know that a historic global cooling called the Little Ice Age, from 1450 to 1850 A.D., coincided with two periods of decreased solar activity.
Evidence shows that around 5,200 years ago, solar output first dropped precipitously and then surged over a short period. It is this huge solar energy oscillation that Thompson believes may have triggered the climate change he sees in all those records.
“The climate system is remarkably sensitive to natural variability,” he said. “It’s likely that it is equally sensitive to effects brought on by human activity, changes like increased greenhouse gases, altered land-use policies and fossil-fuel dependence.
“Any prudent person would agree that we don’t yet understand the complexities with the climate system and, since we don’t, we should be extremely cautious in how much we ‘tweak’ the system,” he said.
“The evidence is clear that a major climate change is underway.”

White-Black unions in England and the US

White-Black unions in England and the US

Ethnic and Racial Studies 1 September 2002, vol. 25, no. 5, pp. 728-754(27)

Unions between blacks and whites: England and the US compared

Model S.; Fisher G.

Abstract:

In this article, US and UK census data are used to compare the propensity for matches between blacks and native born whites in England and the US. Blacks are disaggregated into three ethnic groups: Black Caribbeans, Residual Blacks and, in the US, African Americans. The first group receives the most theoretical attention. Both raw percentages and parameters that control for several covariates – such as age, education and city of residence – are examined. The results indicate that, with or without controls and irrespective of ethnicity, blacks in Britain are significantly more likely to have a native born white partner than their US counterparts. These findings accord with assimilation theory, but the article's conclusion suggests that, in both countries, the assimilation of people of African descent operates differently from the assimilation of whites.

[...]

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Lithuanian Y-chromosomes and mtDNA

Lithuanian Y-chromosomes and mtDNA

Annals of Human Genetics (OnlineEarly)
doi:10.1046/j.1529-8817.2003.00119.x

Y Chromosome and Mitochondrial DNA Variation in Lithuanians
D. Kasperaviit et al.

Summary

The genetic composition of the Lithuanian population was investigated by analysing mitochondrial DNA hypervariable region 1, RFLP polymorphisms and Y chromosomal biallelic and STR markers in six ethnolinguistic groups of Lithuanians, to address questions about the origin and genetic structure of the present day population. There were no significant genetic differences among ethnolinguistic groups, and an analysis of molecular variance confirmed the homogeneity of the Lithuanian population. MtDNA diversity revealed that Lithuanians are close to both Slavic (Indo-European) and Finno-Ugric speaking populations of Northern and Eastern Europe. Y-chromosome SNP haplogroup analysis showed Lithuanians to be closest to Latvians and Estonians. Significant differences between Lithuanian and Estonian Y chromosome STR haplotypes suggested that these populations have had different demographic histories. We suggest that the observed pattern of Y chromosome diversity in Lithuanians may be explained by a population bottleneck associated with Indo-European contact. Different Y chromosome STR distributions in Lithuanians and Estonians might be explained by different origins or, alternatively, be the result of some period of isolation and genetic drift after the population split.

mtDNA in Iran and India

mtDNA in Iran and India

This article is a great survey of South and Southwest Asian mitochondrial diversity, showing a sharp difference between India and Iran, with the former having a high occurrence of "Proto-Asian" mtDNA types whose frequence falls drastically in Iran.

Indians have traditionally been characterized as being part of the periphery of the Caucasoid race. The subequatorial racial element which distinguishes Indians from Caucasoids-proper has been named Veddoid, Australoid or Palaeo-Indid by various researchers. These new genetic studies have shown Indians to be of mainly dual origins, with West Eurasian racial elements being added to a native South Asian base which persists more strongly in non-caste and southern populations of the subcontinent, and manifests itself primarily in Indian matrilineages.

BMC Genet. 2004 Aug 31;5(1):26.

Most of the extant mtDNA boundaries in South and Southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans

Metspalu et al.

BACKGROUND: Recent advances in the understanding of the maternal and paternal heritage of south and southwest Asian populations have highlighted their role in the colonization of Eurasia by anatomically modern humans. Further understanding requires a deeper insight into the topology of the branches of the Indian mtDNA phylogenetic tree, which should be contextualized within the phylogeography of the neighboring regional mtDNA variation. Accordingly, we have analyzed mtDNA control and coding region variation in 796 Indian (including both tribal and caste populations from different parts of India) and 436 Iranian mtDNAs. The results were integrated and analyzed together with published data from South, Southeast Asia and West Eurasia. RESULTS: Four new Indian-specific haplogroup M sub-clades were defined. These, in combination with two previously described haplogroups, encompass approximately one third of the haplogroup M mtDNAs in India. Their phylogeography and spread among different linguistic phyla and social strata was investigated in detail. Furthermore, the analysis of the Iranian mtDNA pool revealed patterns of limited reciprocal gene flow between Iran and the Indian sub-continent and allowed the identification of different assemblies of shared mtDNA sub-clades. CONCLUSIONS: Since the initial peopling of South and West Asia by anatomically modern humans, when this region may well have provided the initial settlers who colonized much of the rest of Eurasia, the gene flow in and out of India of the maternally transmitted mtDNA has been surprisingly limited. Specifically, our analysis of the mtDNA haplogroups, which are shared between Indian and Iranian populations and exhibit coalescence ages corresponding to around the early Upper Paleolithic, indicates that they are present in India largely as Indian-specific sub-lineages. In contrast, other ancient Indian-specific variants of M and R are very rare outside the sub-continent.

Racial Affinities of Prehistoric East Africans

Racial Affinities of Prehistoric East Africans

Afrocentrists and Nordicists alike tend to assert that early East Africans were "Negroid". Since East Africa was the source of multiple migrations of early humans out of Africa, this allows the former to assert a "Negroid" stage in the evolution of Eurasians, or to postulate a later (mythological) stage of "Negroid" East African culture-bearers. Nordicists of the other hand, dissatisfied with the paucity to non-existence of genuine Sub-Saharan African genetic markers in Southeastern Europe have insinuated that Y-haplogroup E3b which originated in East Africa 26ky ago is "Negroid" or that mtDNA haplogroup M1 which according to some also originated in East Africa in Paleolithic times is also "Negroid".

W.W. Howells' study of world craniometric variation is especially relevant to the racial affinity of East Africans before the expansion of Negroids into the region. Howells studied some 2,500+ skulls from 28 populations of recent Homo sapiens based on 57 metric variables [1], including skulls from the Teita tribe of East Africa. These recent Teita tribesmen (and women) clustered with other Sub-Saharan Africans, indicating that (as is obvious) recent Kenyans belong primarily to the Negroid race.

Howells then studied prehistoric East Africans and other humans from around the world to determine whether or not they show any affinities with living races [2]. He did this to examine whether the morphological complexes of modern races can be discerned in remote times. Using the same multivariate approach he studied the Elmenteita, Nakuru and Willey's Kopje skulls from Kenya. His conclusion was that there is no racial continuity between recent Negroid East African skulls and these prehistoric remains, as the following passage illustrates ([2, p. 41]:
(...) The DISPOP [Dienekes: DISPOP is Howells' program] results here are not indicative of anything, except a general non-African nature for all these skulls. Display of POPKIN distances (infra) reinforces this and seems to find nearer neighbors among such more generalized populations as Peru, Guam, or Ainu, but also Europeans or even Easter Island.
Remembering that the Teita series (Bantu speakers of southeastern Kenya), and the recent East African skulls in table 4 above, do clearly exhibit African affiliations, it is fair to say, contra Rightmire, that there seems to be no clear continuity here in late prehistory. On the broad scale, looking at an "Out-of-Africa" scenario, one would expect that, in some region between southern and northeastern Africa, some differentiation would have been taking place within a Homo sapiens stock, evolving into something beginning to approximate later Sub-Saharan peoples on the one hand, and evolving in another direction on the other hand. East Africa would be a likely locale for appearance of the latter. So anyone is welcome to argue that this is what Elmenteita et al. are manifesting. The ensuing picture for East Africa, that is to say, would later have beeen changed through replacement by the expansion of Bantu or other "Negroid" tribes.


[1] Howells WW (1989) Skull shapes and the map: craniometric analyses in the dispersion of modern Homo. Peabody Museum Papers 79:1-189.
[2] Howells WW (1995) Who's Who in skulls: ethnic identification of crania from measurements. Peabody Museum Papers 82:1-108.

Population Genetics of Estonians

Population Genetics of Estonians

A genetic study on Estonians agrees with a multivariate craniometric study (Homo. 2002;52(3):240-53.) in proposing that the Finno-Ugrians were originally a separate race from both Caucasoids and Mongoloids.

Anthropol Anz. 2000 Jun;58(2):137-54.

A population genetic characterization of Estonians.
Heapost L.

This paper discusses the genetic characterization of Estonians on the basis of eight blood group systems, and the traits of PTC tasting and colour blindness in 40 Estonian population samples from various parts of the country. The allele frequencies for the total Estonian population and for the four most different regions are presented. The survey shows genetic heterogeneity within the Estonians; the greatest genetic differences were observed in West-East direction. The West-Islands, West, and North Estonia differ from the other regions (East, South-East, also South-West and Central Estonia--which form a compact cluster). The mean allele frequencies of the Estonians are comparable to those typical for populations from North and East Europe, but the allele frequencies of Estonians are characterized by tendencies in two opposite (western and eastern) directions, like in other Finno-Ugric populations and concerning other anthropological traits. Estonians reveal closest similarities to the nearest neighbouring populations, regardless of their language group. The genetic heterogeneity and antagonistic traits in Estonians seem to be traces of the original genetic structure of Finno-Ugric ancestor populations which were neither Mongoloid nor Caucasoid.

Samaritan mtDNA and Y chromosomes

Samaritan mtDNA and Y chromosomes

Hum Mutat. 2004 Sep;24(3):248-60.

Reconstruction of patrilineages and matrilineages of Samaritans and other Israeli populations from Y-Chromosome and mitochondrial DNA sequence Variation.
P. Shen et al.

The Samaritan community, which numbered more than a million in late Roman times and only 146 in 1917, numbers today about 640 people representing four large families. They are culturally different from both Jewish and non-Jewish populations in the Middle East and their origin remains a question of great interest. Genetic differences between the Samaritans and neighboring Jewish and non-Jewish populations are corroborated in the present study of 7,280 bp of nonrecombining Y-chromosome and 5,622 bp of coding and hypervariable segment I (HVS-I) mitochondrial DNA (mtDNA) sequences. Comparative sequence analysis was carried out on 12 Samaritan Y-chromosome, and mtDNA samples from nine male and seven female Samaritans separated by at least two generations. In addition, 18-20 male individuals were analyzed, each representing Ethiopian, Ashkenazi, Iraqi, Libyan, Moroccan, and Yemenite Jews, as well as Druze and Palestinians, all currently living in Israel. The four Samaritan families clustered to four distinct Y-chromosome haplogroups according to their patrilineal identity. Of the 16 Samaritan mtDNA samples, 14 carry either of two mitochondrial haplotypes that are rare or absent among other worldwide ethnic groups. Principal component analysis suggests a common ancestry of Samaritan and Jewish patrilineages. Most of the former may be traced back to a common ancestor in the paternally-inherited Jewish high priesthood (Cohanim) at the time of the Assyrian conquest of the kingdom of Israel.

mtDNA from Xinjiang

mtDNA from Xinjiang

A new study quantifies the level of Caucasoid admixture in various populations of the Xinjiang province of China, which ranges from 0% in the Han Chinese to 43% in the Uygur.

Mol Biol Evol.
2004 Aug 18 [Epub ahead of print]

Different Matrilineal Contributions to Genetic Structure of Ethnic Groups in the Silk Road Region in China.

Yao YG

Previous studies have shown that there were extensive genetic admixtures in the Silk Road region. In the present study, we analyzed 252 mtDNAs of five ethnic groups (Uygur, Uzbek, Kazak, Mongolian, and Hui) from Xinjiang Province, China (where once was the via route of the Silk Road), together with some reported data from the adjacent regions in Central Asia. In a simple way, we classified the mtDNAs into different haplogroups (monophyletic clades in the rooted mtDNA tree) according to the available phylogenetic information and compared their frequencies to show the differences among the matrilineal genetic structures of these populations with different demographic histories. With the exception of 8 unassigned M(*), N(*) and R(*) mtDNAs, all the mtDNA types identified here belonged to defined subhaplogroups of haplogroups M and N (including R) and consisted of subsets of both the eastern and western Eurasian pools, thus providing direct evidence in supporting the suggestion that Central Asia be the place of the genetic admixture of the East and the West. Although our samples were from the same geographic location, a decreasing tendency of the western Eurasian-specific haplogroup frequency was observed, with the highest frequency present in Uygur (42.6%) and Uzbek (41.4%), followed by Kazak (30.2%), Mongolian (14.3%), and Hui (6.7%). No western Eurasian type was found in Han Chinese samples from the same place. The frequencies of the eastern Eurasian-specific haplogroups also varied in these samples. Combined with the historical records, ethno-origin, migratory history, and marriage custom might play different roles in shaping the matrilineal genetic structure of different ethnic populations resided in this region.
 http://dienekes.blogspot.com/2004_08_01_archive.html#

mtDNA of ancient central Asians


mtDNA of ancient central Asians

An interesting new paper confirms the anthropological and archaeological picture of a westward spread of Caucasoids in Central Asia in early prehistoric times, followed by the spread of Mongoloids in the opposite direction during the 1st millennium BC. The Caucasoid-Mongoloid hybrid population resulting from these interactions is similar in terms of mtDNA with present-day Central Asians with some noted differences (e.g., presence of additional West Eurasian haplogroups). In the ancient samples, West Eurasian haplogroups H, HV, I, T*, T1, U*, U1, U5, U5a1 and W were represented:
  • HV sequences have matches in the Central Mediterranean region
  • H sequences are split between the common Cambridge Reference Sequence (CRS) found in many populations, and two other sequences found in the Central Mediterranean and the Caucasus
  • The I sequence is present in a modern Central Asian and also in individuals from the Caucasus
  • The W sequence is widespread in West Eurasia
  • T* sequences are widespread in Europe, the Near East and the Central Mediterranean region
  • T1 is widespread in West Eurasia, but also found sporadically in East Eurasia
  • The U1a sequences are found in Turks, Armenians and Caucasians
  • The U5a sequence has been found in an Egyptian
  • The U5a1 sequence is frequent in the Caucasus and present in Europe, while a different U5a1 was reported previously in Mongolia
The East Eurasian haplogroups belong to A*, M*, M4 and G2:
  • The M* sequence was observed in an Indian individual
  • The M4 sequence has not been previously reported
  • The G2 sequence is found in present-day China and Central Asia
  • One A sequence is found in present-day Central Asians and Indians, while the other two have a motif found in a modern Chukchi
Most (78%) of the sequences are of West Eurasian (Caucasoid) origin, but before the 7th c. BC, East Eurasian (Mongoloid) sequences are absent, although they could be present up to 20.6% (p<0.05).
Proc R Soc Lond B Biol Sci. 2004 May 7;271(1542):941-7. 

Unravelling migrations in the steppe: mitochondrial DNA sequences from ancient central Asians.
Lalueza-Fox C et al.

This study helps to clarify the debate on the Western and Eastern genetic influences in Central Asia. Thirty-six skeletal remains from Kazakhstan (Central Asia), excavated from different sites dating between the fifteenth century BC to the fifth century AD, have been analysed for the hypervariable control region (HVR-I) and haplogroup diagnostic single nucleotide polymorphisms (SNPs) of the mitochondrial DNA genome. Standard authentication criteria for ancient DNA studies, including multiple extractions, cloning of PCR products and independent replication, have been followed. The distribution of east and west Eurasian lineages through time in the region is concordant with the available archaeological information: prior to the thirteenth-seventh century BC, all Kazakh samples belong to European lineages; while later an arrival of east Eurasian sequences that coexisted with the previous west Eurasian genetic substratum can be detected. The presence of an ancient genetic substratum of European origin in West Asia may be related to the discovery of ancient mummies with European features in Xinjiang and to the existence of an extinct Indo-European language, Tocharian. This study demonstrates the usefulness of the ancient DNA in unravelling complex patterns of past human migrations so as to help decipher the origin of present-day admixed populations.