Move over Jurassic Park, it seems the idea of bringing extinct animals back to life is now becoming more science rather than science fiction. The idea of reviving long extinct species has fascinated scientists for generations. Now, they have brought the idea one step closer to reality as scientists from Harvard University have managed to insert wooly mammoth DNA into the code of Asian elephants.

Geneticist George Church and his colleagues, using a technique knowns as CRISPR, successfully inserted mammoth DNA for small ears, subcutaneous fat, and hair length and color into the DNA of elephant skin cells.

The woolly mammoth has been extinct for thousands of years with the last of its species dying out about 3,600 years ago. But scientists now believe it may be possible to bring these and other species back from the grave.

We won't be seeing mammoths anytime soon, however, as Church says "there is more work to do." Church and his colleagues plan to continue their work with Church adding, "But we plan to do so."

According to Church, splicing mammoth DNA into elephant cells is only the first step in a lengthy process. Next, they need to figure out how to turn hybrid cells into specialized tissues and determine if they product the right traits. For example, they researchers need to be sure the cells produce hair of the correct color and texture.

From there, researchers to plan to grow the hybrid cells in an artificial womb as scientists and animal rights activists alike have deemed it unethical to grow them in a living elephant's womb.

If the researchers can get these hybrid mammoth-elephants to survive, they hope to then engineer an elephant that can survive in cold climates where it should face fewer threats from humans. Once they get these hybrid creatures to survive, they can incorporate more mammoth DNA in an effort to revive the ancient species that once roamed the Earth.

Mammoths aren't the only animals that scientists have tried to revive from oblivion. In 2003, scientists briefly revived the Pyrenean ibex that went extinct in 2000, by cloning a frozen tissue sample of the goat. However, after it was born, the clone only survived for 7 minutes.

Some critics worry that the ability to revive once extinct species will undermine conservation as we know it today and encourage the destruction of natural habitats.

"It totally ignores the very practical realities of what conservation is about,"conservation ecologist at Duke University, Stuart Pimm says.

Other scientists have been cautiously accepting of the idea. Stanley Temple, an ecologist at the University of Wisconsin-Madison told Live Science in August 2013, "We can use some of these techniques to actually help endangered species improve their long-term viability."