Bringing back the Woolly Mammoth and other Extinct Creatures may be Impossible

An extinct rat that once lived on an island in the Indian Ocean may have put the kibosh on scientists’ dreams of resurrecting more famous extinct animals like the woolly Mammoth. The Christmas Island rat disappeared just over 100 years ago, but researchers now say even its detailed genome isn’t complete enough to bring it back to life.

Douglas McCauley, an ecologist at the University of California, Santa Barbara, who was not involved with the study, said that the work “shows both how wonderfully close—and yet—how devastatingly far” scientists are from being able to bring back extinct species by genetically transforming a close relative in what’s called de-extinction.The Mammoth once kept arctic shrubs and trees under control and fertilized grasses. Indeed, a Colossal Laboratories and Biosciences aims to transform elephants into, or, at least, Mammoth animals.

There is a lot of hope and hype that de-extinction will save us” from ecosystems failing, McCauley says.To bring back an extinct species, scientists would first need to sequence its genome and then edit a close relative’s DNA to match it. Next comes the challenge of making embryos with the revised genome and bringing them to term in a living surrogate mother. So far, scientists have sequenced the genomes of about 20 extinct species, including a cave bear, passenger pigeon, and several types of Mammoth and moas. But no one has yet reported re-creating the extinct genome in a living relative.

Gilbert and Lin extracted DNA from the skins of two preserved Christmas Island rats and sequenced it many times over to get as much of the genome as possible. They achieved more than 60 times’ coverage of it. Old DNA only survives in small fragments, so the team used the genome of the Norway rat as a reference to piece together as much as possible of the vanished rat’s genome. Comparing the two genomes revealed almost 5% of the Christmas Island rat’s genome was still missing, Lin, Gilbert, and their colleagues report today in Current Biology.