Rats once ruled Christmas Island, a 135-square-kilometer isle about 350 kilometers south of Indonesia’s Java. While chubby bulldog rats (Rattus nativitatis) roamed the island’s forest floors, it was Christmas Island rats (Rattus macleari), with their long, thick fur and rounded ears, that truly had the run of the place. According to British paleontologist Charles William Andrews, who wrote a monograph about his 1897 observations of the island, “swarms” of them appeared everywhere as soon as the sun set. Yet the last documented sighting of the species would occur a mere 18 years later. By 1908, the rats were extinct, likely the victims of a disease brought to their shores by stowaway brown rats (Rattus rattus).
Such losses were once considered irreversible. But now, with ever-improving genetic technologies, researchers are exploring the possibility of de-extinction, which can involve resurrecting a species by engineering the genome of a living species to match ...
