An extinct rat shows CRISPR’s limits for resurrecting species

Before the early 1900s, if it walked like a Christmas Island rat and talked like a Christmas Island rat, it probably was a Christmas Island rat. But if one of these now-extinct rats ever walks the Earth again, it will most likely be a genetically modified Norway brown rat. And the rodent won’t be as similar to the Christmas Island rat as some would hope, a new study finds.

With the advent of gene-editing technology such as CRISPR, scientists have shifted from cloning to genetic engineering as the most promising method for “de-extinction,” or the resurrection of species…