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I3-Y18195
I3c (Y18195) is a rare but phylogenetically informative branch of haplogroup I3 found primarily around the Caucasus–Zagros interaction zone. Its deep divergence time indicates survival of an isolated Upper Paleolithic paternal line that persisted through the climatic fluctuations of the Last Glacial Maximum. I3c likely represents groups inhabiting mountain foothills and highland refugia that connected the Caucasus, eastern Anatolia, and the Zagros corridor.
Modern occurrences are concentrated in northeastern Turkey, Armenia, western Iran and parts of the South Caucasus. Low frequencies have been detected in the Levant and occasionally in southeastern Europe, likely via ancient trans-Anatolian movements.
I3c branches alongside I3a and I3b as one of the three major sublineages of I3. Y18195 and downstream SNPs define a tight cluster that reflects ancient isolation. Its slow diversification and geographic confinement contrast with the more complex radiations of I1 and I2.
I3c provides a rare window into Upper Paleolithic paternal diversity in the highland Near East. Its presence in modern populations at low frequencies underscores how some deeply divergent West Eurasian lineages survived in ecological refugia far from major demographic pulses.