Caucasian Ancestry – Haplogroup G
History of Y-DNA Haplogroup G
Sometime 60 millennia (60,000 years) ago, a lineage started to emigrate from Africa following the steps of the animal herds on which they depended for survival. This lineage derived from “Y-chromosomal Adam” had the SNP mutation M168. During this migration, at about 45,000 years ago, another mutation SNP M89 occurred. This mutation exists in 90-95% of non-Africans. While this lineage continued their migration into the Middle East, several other mutations arose from this lineage (SNP M89). The SNP M201 which defines the Haplogroup G (and ten other associated SNP markers) emerged from the SNP M89.
The Haplogroup G ancestors chose to reside within the Fertile Crescent at around the end of the last ice age (between 10,000 to 15,000 BP). They began to grow their own food, which brought the Neolithic Revolution upon humankind. This revolution saw a major shift from humans been nomadic hunters to farmers.
The Neolithic revolution was a major event in human history and the period that followed expectedly brought about a rapid alteration in the social structure of human societies. As populations grew larger thanks to the constant supply of food, dispersion inevitably occurred.
The emigration of large groups of migrants from the Fertile Crescent schlepped through the Mediterranean, through Turkey and the Balkans, and reached the Caucasus Mountains.
Geographical Distribution of Y-DNA Haplogroup G
The geographical distribution of Haplogroup G agrees with its history. The frequency decreases from the Near East to Europe, an attribute it shares with Haplogroups J and E. Accordingly, relative to central Europe, the Mediterranean coast has higher frequencies of Haplogroup G. Haplogroup G is widely distributed throughout Western Europe countries. It is less prevalent across Asia and northern Africa. However, in most populations, Haplogroup G tends to have a relatively low frequency. Haplogroup G is most frequent in Armenia, Azerbaijan, Georgia, and South Russia—a geographical enclave collectively called Caucasia, or the Caucasus. History does tell of an area southeast of the Caucasus Mountains being the choice area of settlement for ancestors with Haplogroup G.
Other populations of the G haplogroup ancestors throughout Europe then emerged after the glaciers receded. Men with Haplogroup G eventually moved on to other areas in both eastward and westward directions to the Indian subcontinent and Europe respectively. The reason for this emigration is not certain. Common reasons that pop up are slavery, invasion, or agricultural-related movements.
An important distinction of the entire human population of the G haplogroup is that there is relatively little genetic variation. The little variations that exist often follow geographical distribution models. This propels the theory that the presence of geographical barriers, like mountain ranges, may have limited or prevented interaction between different groups of people.
With the correlation between genetic variation and geography being significant and prevalent within Haplogroup G population, Haplogroup G provides concrete examples to explain how social structure, such as ethnicity, language, or race, explains the genetic variation. Even better, the examples go beyond the general haplogroup and even exist within the subclades of the haplogroup G.
Haplogroup G in the Caucasus
Modern-day Armenia, Azerbaijan, Georgia, and Southwest Russia form the Caucasus region. The highest prevalence of the G haplogroup exists in this region. The geography of the region characterized by many natural barriers markedly contributes to the region’s history of isolation and gene flow. Consequently, the region features a varied mixture of languages and religions.
In the past, the Caucasus region strategically served as a corridor of human migration between continents. Of prime importance to this role was the Caucasian Mountains that forced most travelers into the easily accessible lowlands.
Nevertheless, some populations braced the odds to settle in the highlands. These populations in the highlands subsequently developed distinct social customs that involved men remaining in the land of their ancestors, and having to bring their wives to the highlands to live with them.
This practice is the core reason why highland populations are markedly distinct from lowland populations to this day. A study of five isolated populations in Dagestan proves this assertion in that the highland populations showed lower Y-chromosomal diversity than lowland populations.
Furthermore, according to the study, while haplogroup comparisons indicated that the highland populations had a Near Eastern origin, the lowland populations present evidence of influence from Central Asian and Near Eastern populations.
Haplogroup G in the Middle East
In the Middle East, more headway has been recorded in understanding the population history of Iran than for any other population history in the region. Even then, the country features an interesting mix of populations.
Of primal importance to this article is the occurrence of two geographical neighbors that speak languages that belong to two different linguistic families. They are the Iranian Arabs who speak a Semitic language and the Bakhtiari who speak an Indo-European language.
The details of a study conducted in the region pointed out that Bakhtiari men had Haplogroup G amongst their top four most prevalent haplogroups. In fact, the G haplogroup existed in 15% of men tested. In contrast, only 6% of Iranian Arabs men tested had Haplogroup G.
This study in addition to further analysis of Y-STR haplotypes of men belonging to Haplogroups G and F as well as data accumulated from mitochondrial DNA showed that language was not a barrier to gene flow between the two groups.
Furthermore, the details of this study indicate that the patterns of genetic variation in the study, and by extension in both populations, correlated better with geography than with language.
Haplogroup G in Europe
The Haplogroup G, especially subclade G2a, has been a useful genetic marker in the reconstruction of the spread of agriculture into Europe during the Neolithic period. Some quarters portend that the Neolithic agriculture spread may have occurred by sea rather than by land. This notion is fueled by a study that shows the frequency of the G haplogroup in Croatia to be quite low with the exception of one island, occupying the southernmost location and is distant from the mainland.
10 Jan 2017 / rarikola / 7
Tags: Azerbaijan, Balkans, Caucasian, Caucasus Mountains, Dagestan, Fertile Crescent, genetic variation, Georgia, Haplogroup G, Mediterranean, Middle East, mutation SNP M89, Neolithic agriculture, nomadic hunters to farmers
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