Recent studies of African populations have attracted particular attention. New analyses have detected signals of archaic admixture in the genomes of Africans from unknown hominins not directly related to Neanderthals or Denisovans. The strongest signals of archaic origin are found in hunter-gatherer groups (e.g., Pygmies or San), which have fragments of very deep (on the order of a million years) origin in their DNA. In doing so, different African communities show distinct profiles of archaic admixture, indicating multiple independent episodes of archaic contact rather than a single event. Numerous waves of interbreeding have also been identified - both with Neanderthals and with various Denisovan groups. Analyses show at least three independent episodes of gene exchange with Denisovans (from different Denisovan populations). DNA fragments of so-called "superarchaic" hominins - such evolutionarily distant branches of hominins that their genomes are not known (perhaps Homo erectus or others) - have also been found in human genomes. Up to about 1% of the Denisovan genome contains DNA from these unknown groups, suggesting that fragments of their genome made their way into Homo sapiens through interbreeding between archaic and modern populations.