Overview
I2c represents a small but phylogenetically crucial offshoot of the I2 macro-lineage with its deepest roots in the highland and piedmont regions bridging Anatolia, the Caucasus and the northern Zagros. Although rare today, I2c appears to preserve an early branching event within the I2 structure that unfolded during the late Upper Paleolithic or early Holocene among forager groups occupying the mountainous eco-zones of Southwest Asia. Its rarity is not evidence of unimportance: the existence of I2c demonstrates that the I2 radiation was not limited to the European refugia but extended into the ecotones of eastern Anatolia and the Transcaucasus.
Genetic continuity in these regions during the early Holocene allowed I2c lineages to participate in the admixture zones linking Caucasus hunter-gatherers, early Holocene Iranian Plateau foragers and the pre-Neolithic cultural horizon stretching across Anatolia. As a result, I2c contributes to understanding the formation of CHG-related and Zagros-related ancestry layers before the advent of agriculture in the Near East.
Geographic distribution
Today, I2c is exceedingly rare but occurs at trace frequencies in Armenia, Georgia, eastern Turkey and northwestern Iran. Some scattered individuals also appear in the Levant and in southeastern Europe, where their presence likely reflects ancient movements from the Anatolia–Caucasus frontier. Low-frequency occurrences in Europe are typically due to founder events or isolated introductions rather than sustained local ancestry.
Among diaspora populations outside Eurasia, I2c is encountered only sporadically.
Ancient DNA
- High coverage ancient genomes directly assigned to I2c are not yet available, but several early Holocene Caucasus and Iranian highland individuals show upstream I2 markers compatible with I2c positioning.
- The geographic corridor linking the Caucasus foothills and northwestern Iran yields multiple Mesolithic genomes showing deep West Eurasian hunter-gatherer ancestry, within which I2c may have existed as a small paternal line.
- Genetic patterns in early Neolithic Anatolia and the southern Caucasus allow for modeling of a low-frequency I2c presence.
Phylogeny & subclades
I2c branches into several minor but deeply divergent subclades, each representing early forager micro-communities in the Caucasus–Zagros transition zone. Within the atlas, we model the lineage as consisting of two principal downstream groups: I2c1 and I2c2.
- I2c1 – Caucasus oriented early Holocene branches
- I2c2 – Zagros highland and northwest Iran oriented microclades
Notes & context
I2c is an essential but often overlooked piece of the early West Eurasian paternal landscape. Its presence suggests a wider early Holocene range for I2 than is typically assumed.
References & external links