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Posts Tagged ‘Genetics’

From Ethiopia to Chile: a 7-Year Walk to Trace Man’s Global Migration

Posted by addisethiopia / አዲስ ኢትዮጵያ on January 10, 2013

Fascinating!

A two-time Pulitzer Prize winning American writer and Journalist and National Geographic Fellow Paul Salopek is undertaking an ambitious expedition to retrace on foot the path our ancient ancestors traveled as they migrated across the world.

The Ethiopia-to-Chile walk — which took human ancestors some 50,000 years to make — is called Out of Eden and is sponsored by National Geographic, the Knight Foundation and the Pulitzer Center for Crisis Reporting. A two-time Pulitzer Prize winner, the American plans to write one major article a year with periodic updates every 100 miles or so.

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mtDNA Variation in East Africa

HumanMigrationLanguage diversity in East Africa fits well with its complicated genetic history. In Fleming words, ‘‘Ethiopia by itself has more languages than all of Europe, even counting all the so-called dialects of the Romance family’’ (Fleming, 2006).

All African linguistic phyla are found in East Africa:

  • Afro-Asiatic (AA)

  • Nilo-Saharan,

  • Niger-Congo

  • Khoisan

Among them, AA is the most differentiated, being represented by three:

  • Omotic

  • Cushitic

  • Semitic

of its six major clades:

  • Chadic

  • Berber

  • Egyptian

Omotic and Cushitic are considered the deepest clades of AA, and both are found almost exclusively in the Horn of Africa, along with the linguistic relict Ongota that is traditionally assigned to the Cushitic family but whose classification is still widely debated (Fleming, 2006).

These observations are in agreement with a North-Eastern African origin of the AA languages, most probably in pre-Neolithic times

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Posted in Ethiopia, Ethnicity, Genetics & Anthropology | Tagged: , , , , , , , , | 1 Comment »

Genomics and African Queens: Diversity Within Ethiopian Genomes Reveals Imprints of Historical Events

Posted by addisethiopia / አዲስ ኢትዮጵያ on June 21, 2012

Researchers have started to unveil the genetic heritage of Ethiopian populations, who are among the most diverse in the world, and lie at the gateway from Africa. They found that the genomes of some Ethiopian populations bear striking similarities to those of populations in Israel and Syria, a potential genetic legacy of the Queen of Sheba and her companions.

The team detected mixing between some Ethiopians and non-African populations dating to approximately 3,000 years ago. The origin and date of this genomic admixture, along with previous linguistic studies, is consistent with the legend of the Queen of Sheba, who according to the Ethiopian Kebra Nagast book had a child with King Solomon from Israel and is mentioned in both the Bible and the Qur’an.

Ethiopia is situated in the horn of Africa, and has often been regarded as one of the gateways from Africa to the rest of the world. The Ethiopian region itself has the longest fossil record of human history anywhere in the world. Studying population genetics within this diverse region could help us to understand the origin of the first humans.

“From their geographic location, it is logical to think that migration out of Africa 60,000 years ago began in either Ethiopia or Egypt. Little was previously known about the populations inhabiting the North-East African region from a genomic perspective. This is the first genome study on a representative panel of Ethiopian populations,” explains Luca Pagani, first author from the Wellcome Trust Sanger Institute and the University of Cambridge. “We wanted to compare the genome of Ethiopians with other Africans to provide an essential piece to the African — and world — genetic jigsaw.”

They found that the Ethiopian genome is not as ancient as was previously thought and less ancient than the genomes of some Southern African populations. There were also links with other populations.

“We found that some Ethiopians have 40-50% of their genome closer to the genomes of populations outside of Africa, while the remaining half of their genome is closer to populations within the African continent,” says Dr Toomas Kivisild, co-author from the University of Cambridge. “We calculated genetic distances and found that these non-African regions of the genome are closest to populations in Egypt, Israel and Syria, rather than to the neighbouring Yemeni and Arabs.”

The team found that these two groups of African and non-African people mixed approximately 3,000 years ago, well before the historically-documented Islamic expansions and the colonial period of the last centuries.

An earlier study found that Ethio-Semitic, an Ethiopian language belonging to a linguistic family primarily spoken in the Middle East, split from the main Semitic group 3,000 years ago, around the same time as the non-African genomic component arrived in Ethiopia. All this evidence combined fits the time and locations of the legend of the Queen of Sheba, which describes the encounter of the Ethiopian Queen and King Solomon.

“None of this research would have been possible without the superb fieldwork of our Ethiopian colleagues Professor Endashaw Bekele and Dr Ayele Tarekegn over many years. The outstanding genetic diversity present within the peoples of Ethiopia is a rich resource that will contribute greatly, both to our understanding of human evolution and the development of personalised medicine.” says Dr Neil Bradman, co-lead author from UCL (University College London). “The Ethiopian Government has a practice of encouraging genetic research, a policy that bodes well for the future.”

“Our research gives insights into important evolutionary questions,” says Dr Chris Tyler-Smith, co-lead author from the Wellcome Trust Sanger Institute. “We see imprints of historical events on top of much more ancient prehistoric ones that together create a region of rich culture and genetic diversity. The next step for our research has to be to sequence the entire genomes, rather than read individual letters, of both Ethiopian people and others to really understand human origins and the out-of-Africa migration.”

Source: ScienceDaily

Images: courtesy of artist Addis Gebru

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Posted in Ethiopia, Ethnicity, Genetics & Anthropology | Tagged: , , , , , | 4 Comments »

Why Do ‘Black’ Pacific Populations of Melanesia Have Blond Hair?

Posted by addisethiopia / አዲስ ኢትዮጵያ on May 6, 2012


Blond hair is relatively common in the Solomon Islands, even though the skin pigmentation of Melanesian peoples is relatively dark.

Naturally blond hair is rare in humans and found almost exclusively in Europe and Oceania. Here, we identify an arginine-to-cysteine change at a highly conserved residue in tyrosinase-related protein 1 (TYRP1) as a major determinant of blond hair in Solomon Islanders. This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance. The mutation is at a frequency of 26% in the Solomon Islands, is absent outside of Oceania, represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide.


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Interesting reading..

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Posted in Curiosity, Ethnicity, Genetics & Anthropology | Tagged: , , , , , , , , , | 2 Comments »

Ethiopian Genetic Components Identified

Posted by addisethiopia / አዲስ ኢትዮጵያ on November 22, 2008

ethio_dna_complex

Different Genetic Components in the Ethiopian Population, Identified by mtDNA and Y-Chromosome Polymorphisms

Seventy-seven Ethiopians were investigated for mtDNA and Y chromosome–specific variations, in order to (1) define the different maternal and paternal components of the Ethiopian gene pool, (2) infer the origins of these maternal and paternal lineages and estimate their relative contributions, and (3) obtain information about ancient populations living in Ethiopia. The mtDNA was studied for the RFLPs relative to the six classical enzymes (HpaI, BamHI, HaeII, MspI, AvaII, and HincII) that identify the African haplogroup L and the Caucasoid haplogroups I and T. The sample was also examined at restriction sites that define the other Caucasoid haplogroups (H, U, V, W, X, J, and K) and for the simultaneous presence of the DdeI10394 and AluI10397 sites, which defines the Asian haplogroup M. Four polymorphic systems were examined on the Y chromosome: the TaqI/12f2 and the 49a,f RFLPs, the Y Alu polymorphic element (DYS287), and the sY81-A/G (DYS271) polymorphism. For comparison, the last two Y polymorphisms were also examined in 87 Senegalese previously classified for the two TaqI RFLPs.

Results from these markers led to the hypothesis that the Ethiopian population (1) experienced Caucasoid gene flow mainly through males, (2) contains African components ascribable to Bantu migrations and to an in situ differentiation process from an ancestral African gene pool, and (3) exhibits some Y-chromosome affinities with the Tsumkwe San (a very ancient African group). Our finding of a high (20%) frequency of the “Asian” DdeI10394AluI10397 (11) mtDNA haplotype in Ethiopia is discussed in terms of the “out of Africa” model.

Posted in Ethiopia | Tagged: , , , , , | 1 Comment »

 
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