A group of Harvard researchers have . The researchers believe they are less than two years away from creating a functioning embryo, although creating a fully-grown mammoth would take much longer.
Bringing back an extinct animal is not easy. The mammoth is an ideal candidate to become the first resurrected species, both because of the large amount of intact mammoth specimens available, and also because its close living relatives, the elephants, still walk the Earth. Still, there is considerable debate around just how to bring the mammoth back to life.
The primary issue is the lack of suitable genetic material for cloning. While a significant amount of mammoth tissue has been found, most of the DNA has been destroyed after being frozen for so long. A team of South Korean researchers are , but the Harvard group is taking a different approach.
The Harvard team is genetically modifying an elephant genome, replacing some elephant genes with mammoth ones. Essentially, they're trying to manually rebuild the mammoth genome. The final product won't be exactly the same as the extinct version, but it'll look pretty much identical.
The Harvard researchers ultimately want to implant their engineered genome inside an elephant embryo, which they expect will happen sometime in the next two years. Once that occurs, they will try to bring the embryo to term using an artificial womb. However, such a feat may not be possible for several more years, so it might be a while before you can see a live woolly mammoth—or a theme park full of them.