Let’s say that in a very close future we have the way to give birth to any creature as long as we have its DNA. Instead of just protecting endangered species, ecological fundamentalists would then decide to resurrect all the species extinct because of mankind. At first, it would be easy : species we knew until the past few years and which unfortunately died out. But as they’d go back in the past, they’d realize that there are many more animals who aren’t on this Earth anymore and could be here again. When would they stop ? And what would be the consequences on the balance of our actual ecosystem ? The reintroduction of some type of lizard, or even a rabbit, could change the face of the planet… not necessarily for the best.

Source of the idea here