Relictual

A relict is a surviving remnant of a natural phenomenon.

Other uses:

In various places around the world, minority ethnic groups represent lineages of ancient human migrations in places now occupied by more populous ethnic groups, whose ancestors arrived later. For example, the first human groups to inhabit the Caribbean islands were hunter-gatherer tribes from South and Central America. Genetic testing of natives of Cuba show that, in late pre-Columbian times, the island was home to agriculturalists of Taino ethnicity. In addition, a relict population of the original hunter-gatherers remained in western Cuba as the Ciboney people.

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