Definition of "introgress" []

• To infiltrate the genes of one species into the gene pool of another through repeated backcrossing of an interspecific hybrid (verb)

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• "To make a very long story short, it appears that a common human variant of the microcephalin gene originated on a chromosomal region that separated from the human lineage over 1 million years ago, only to come back “introgress” into H. sapiens about 37,000 years ago."