However, this de-extinction of past ecosystem functions may bring future ecological surprises and unexpected negative results for native faunas and floras. Conservation biology as a field must be values and mission-based. Proponents of Pleistocene rewilding aim to reintroduce species that are long gone from our ecosystems or species that were never present but that might serve similar functions in ecosystems. The thought of lions and cheetahs stalking prey is equally amazing and terrifying. Pleistocene rewilding is the advocacy of the reintroduction of extant Pleistocene megafauna, or the close ecological equivalents of extinct megafauna.An extension of the conservation practice of rewilding, which involves reintroducing species to areas where they became extinct in recent history (hundreds of years ago or less).. This is a highly controversial idea that made a big splash when it was proposed. The ethical standing of rewilding, however, seems to trouble many. On some level, these are things many of us would love to see, if only for the sheer exhilaration. It can also involve species from other time periods (or, more accurately, epochs) as well. Pleistocene rewilding is an idea that has been proposed for all sorts of areas across the world. Before committing to a rewilding project however, the benefits and the costs must be addressed to balance the overall necessity and feasibility of the task at hand. With the pros and cons weighed out, the concept of rewilding seems paradoxical. Pleistocene Rewilding is a project that plans to create an ecosystem of the Pleistocene in a special reserve, but as it is impossible to bring back to prehistoric animals, it is proposed to release those animals related to these (eg, the elephant with mammoth, tiger with smilodon, etc.) Pros and Cons of Pleistocene Rewilding It is fascinating to imagine herds of African elephants, camels and wild horses roaming the plains of North America. We look at the pros and cons of rewilding projects that have been implemented in Britain and the USA and take legal and political arguments into consideration. The idea of Pleistocene Rewilding exists on the fringe of conservation biology, but the arguments surrounding it are a great example of how the field is different from most other fields of science. We should not play the role of God because we cannot know the repercussions of such an act. This type of rewilding isn’t just about the Pleistocene, despite its name.