Breeding back is an attempt to assemble the genes of an extinct subspecies or domesticated breed, which may still be present in the larger gene pool of the overall species.
One animal this has been attempted with is the aurochs, an extinct forerunner of cattle. The produce of these attempts is Heck Cattle. An other pominent breeding back effort is the Quagga-Project to bring back the extinct subspecies of the Plains Zebra called Quagga.
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