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Spread of agriculture with haplogroup G2a

Today's science links the spread of agriculture primarily with the migration of haplogroup G2a — the main haplogroup for Abkhazians and the entire Western Caucasus — and to a lesser extent with haplogroup J2. The origin of these haplogroups is considered common. Haplogroup G is believed to have originated in the Middle East during the late Paleolithic, possibly slightly earlier. At that time, all people were hunter-gatherers, and in most cases lived in small nomadic or semi-nomadic tribes. Members of this haplogroup may have been closely associated with the development of agriculture in the early Levant and in that part of the Fertile Crescent, beginning 11,500 years ago to the present. Ancient Y-DNA G2a have also been found in four European Neolithic cultures (LBK in Germany, Remedello in Italy, and Cardial Ware in Southwestern France and Spain), and all results yielded G2a, which is compelling evidence that agriculture originated in the Middle East and was spread by carriers of haplogroup G. Haplogroup G2a constitutes 5 to 10% of the population of Mediterranean Europe, up to 70% in the Western Caucasus, but is quite rare in Northern Europe. The only places where haplogroup G2 exceeds 10% of the population in Europe are Cantabria, Switzerland, Tyrol, south-central Italy (Molise, Central and Southern Apennines), Sardinia, northern Greece (Thessaly) and Crete — all mountainous and relatively isolated regions.

Mountain pastoralists of the Neolithic

Among Abkhazians and peoples of the Western Caucasus, the major haplogroups include G2a3b-P303 and G2a1a-P18. The peoples of the Western Caucasus and Transcaucasia form a single cluster in the genetic space of Eurasia, isolated from other gene pools of Eurasia. There are several theories about the origin of haplogroup G2a in Europe. Chronologically, the first hypothesis about the appearance of Neolithic farmers and pastoralists from Anatolia in Europe falls in the period between 9000 and 6000 years ago. In this scenario, Transcaucasian migrants brought with them goats and sheep, which were domesticated south of the Caucasus about 12,000 years ago. This explains why haplogroup G is more common in mountainous areas, whether in Europe or Asia. The geographical continuity of haplogroup G2a from Anatolia to Thessaly, the Italian peninsula, Sardinia, southern and central France, and Iberia already suggests that G2a may be associated with the Cardial Ware culture (5000-1500 BC). Ancient DNA tests were conducted on skeletons from the LBK site in Germany, as well as the Cardial Ware culture site in southern France (Languedoc-Roussillon) and confirmed that Neolithic farmers in Europe belonged primarily to haplogroup G2a. Currently, haplogroup G2a is found mainly in mountainous regions of Europe, for example, Cantabria (more than 10%), northern Spain, Switzerland (10%), Austria (8%), Auvergne (8%) in central France, mountainous regions of Czechia (5 to 10%), and Wales (4%). This may be because Transcaucasian farmers sought hilly terrain similar to their homeland, which perhaps is well suited for goat breeding. But most likely, G2a farmers fled from Bronze Age invaders, such as Indo-Europeans of haplogroups R1b and R1a, and found refuge in the mountains.

The proposed homeland of haplogroup R1b1a2 and proto-Indo-European migrations are linked to Northern Anatolia and/or the South Caucasus. The Caucasus itself is a peak point for the distribution of haplogroup G. Therefore, it is quite possible that a minority of Caucasian men belonging to haplogroup G (and possibly J2) integrated into R1b communities, crossed the Caucasus, and established themselves on the northern and eastern shores of the Black Sea sometime between 7000 and 5000 BC. Those proto-Indo-Europeans who belonged to R1b1b2a1 and G2a3b1a before the conquest of Europe began in the Balkans around 4000 BC and spread along the entire Atlantic coast from Iberia to the British Isles, where they settled around 2000 BC. In contrast, G2a* and G2a3* are most common in mountainous regions; G2a3b1a is found at low frequency throughout Europe, even in Scandinavia and Russia. Moreover, G2a3b1 is also found in India, especially among higher castes. Eurasia, united by the presence of G2a3b1 throughout Europe and India, is a very strong argument in favor of Indo-European origin. The coalescence age of G2a3b1 also corresponds to the time of Indo-European expansion in the Bronze Age.

Roman expansion period and haplogroup G

It is quite likely that G2a arrived in Europe during the Neolithic or Bronze Age, and the Romans further contributed to the spread of the subclade throughout Italy, which is relatively rich in G2a. Migrations within the Roman Empire likely contributed to a moderate increase of G2a northward into Gaul and Britain; conversely, the frequency of haplogroup G decreases with distance from the border of the Roman Empire. Haplogroup G is extremely rare in Northern and Baltic countries today, despite the fact that agriculture reached those regions at about the same time as Britain or Ireland. This may be a coincidence, as the forest lowlands of northern Germany, Poland, and Northern Europe proved poorer in metals and would not have attracted Bronze Age workers from Transcaucasia. Northeastern Europe also has a rather modest frequency of R1b, further strengthening the links between these two haplogroups.

Alan subclade of haplogroup G2a1

It is believed that the last major spreaders of G2a were the Alans, tribes from Central Asia, descendants of the ancient Sarmatians. Recent paleo-DNA finds of G2a in Bavaria date to 670 AD and undoubtedly confirm this hypothesis. The medieval kingdom of Alania was located in the North Caucasus, in modern Georgia and Ossetia. G2a is observed at slightly higher frequencies in Picardy and Flanders than in neighboring regions. There is an opinion that G2a was brought to northern France and Belgium by the Alans, who traversed continental Europe during the barbarian invasions of the 5th century and briefly established a kingdom in northern France.
Nevertheless, if there are Alan G in Europe, they must certainly belong to subclades different from Neolithic and Bronze Age migrations (not G2a3). G2a1, as the most common subclade in the Western Caucasus today, was relatively recently part of the Alan migrations (from a genetic perspective). In fact, G2a1 has been found along the entire route of Alan migration (Hungary, France, Spain), as well as in Britain. More about the Alans here.

Scythian haplogroup G

The Romans are known to have recruited Scythian and Sarmatian horsemen into their legions. According to C. Scott Littleton in his book From Scythia to Camelot, several Knights of the Round Table were of Scythian origin, and the legend of the Holy Grail itself originated in ancient Scythia. This hypothesis also formed the basis of the 2004 film about King Arthur, which appears with the arrival of Scythian-Roman cavalry in Britain.

More about haplogroup G here.



Spread of agriculture with haplogroup J2a

Haplogroup J is a Near Eastern haplogroup, divided into the conventionally northern haplogroup J2 and the southern haplogroup J1. Haplogroup J2 originated in Northern Mesopotamia and spread westward to Anatolia, the Caucasus, and Southern Europe, as well as eastward to Persia and India. Haplogroups J2 and G2a are possibly associated with the ancient Etruscans (Minoan civilization), Greeks, southern Anatolia, Phoenicians, Assyrians, and Babylonians. In Europe, haplogroup J2 reaches its maximum frequency in Greece (particularly on the island of Crete, Peloponnese, and Thrace), southern and central Italy, southern France, and southern Spain. The ancient Greeks and Phoenicians were the main driving force behind the spread of J2 around the western and southern Mediterranean. Haplogroup J2 is believed to have arrived in Greece from Anatolia between the Neolithic and Bronze Ages. Among the West Caucasian peoples, it is the second major haplogroup after G2a, especially among Georgians and Armenians.

The geographic distribution of haplogroup J2a has a strong correlation with the spread of agriculture in northern Mesopotamia (where it peaks), and further to Anatolia, Greece, the entire Middle East, Iran, Afghanistan, Pakistan, and western India. The significant presence of haplogroup J2 in Italy is associated with early migrations of the earlier Etruscans from the Middle East to central and northern Italy, as well as Greek colonization of southern Italy.

Phoenicians, Jews, Greeks, and Romans contributed to the spread of haplogroup J2a in Iberia. Particularly high frequencies of haplogroup J2a and other Near Eastern haplogroups (J1, E1b1b1, T) in the south of the Iberian Peninsula indicate that the Phoenicians played a more important role than other peoples. This makes sense given that the Phoenicians/Carthaginians were the first to arrive, founding the greatest number of cities (including Gadir/Cadiz, the ancient city of Iberia), and their settlements almost exactly correspond to the higher frequencies of haplogroup J2a.

The Romans certainly contributed to the spread of haplogroup J2 within their borders, judging by the distribution of J2 in Europe (where the frequency is more than 5%), which has a curious resemblance to the borders of the Roman Empire.
The maximum concentration of haplogroup J2a in the world is on the island of Crete (32% of the population). Subclade J2a3d (M319) is presumably native to Crete. Haplogroup J2a also reaches high frequencies in Anatolia, the South Caucasus, Chechnya, and Ingushetia.

Indian branches of haplogroup J2a

In India, haplogroup J2a is more common among higher castes and decreases in frequency with decreasing caste level. This can be explained by the assimilation of local J2a (and R2) by newcomers from Central Asia — Indo-European warriors of R1a1-Z93, who originated from Central Asia (Sintashta culture) and established themselves over several centuries in southern Central Asia, north of the Hindu Kush, before moving on to conquer the Indian subcontinent. J2a reached southern Central Asia with the Neolithic expansion and mixed with the local hunter-gatherer population belonging mainly to R2 (and possibly ancient R1a*).

More about haplogroup J here.