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What do the thylacine, woolly mammoth and gastric-brooding frog all have in common? For one, they’re all extinct – however, there are some scientists who think that the extinction of these animals (and others) might not have to be permanent.

Extinctions have happened throughout history, but the rate of extinction varies. For example, around 66 million years ago huge changes in global climate wiped out whole groups of species, including dinosaurs. Humans have also caused the extinction of many species through hunting, habitat destruction and introducing other species into new ecosystems.

How might it be possible to bring back an extinct species? Firstly, a good quality sample of the species’ genetic code is required. This can be a problem as many specimens held in museums have DNA that has degraded over time. However, advances in technology mean that it is now possible to extract enough genetic information from a range of samples.

Once the species’ genome can be replicated, it needs to be able to grow into an organism. Current techniques involve implanting the DNA of the extinct species into an egg of a related species. The idea is that the fertilised egg is then implanted into the related species where the embryo grows, until the extinct species is reborn. At the moment, the technique is far from perfect and most attempts have failed.

Even if it does become possible to bring back extinct species, there is the question of whether or not we should. Those who support ‘de-extinction’ say that it allows us to correct past mistakes and helps with species conservation. Plus the idea of being able to see living dodos, moas and thylacines is appealing to many.

There are many who oppose the idea. Attempting to bring back extinct species takes a lot of time and money – effort that some conservationists say would be better spent addressing things like habitat destruction which cause extinction in the first place.

Another problem for species that have been extinct for hundreds or thousands of years is that the ecosystems in which they once flourished may have changed or disappeared. Individual species may be able to be brought back, but recreating lost ecosystems may be too hard.

This debate shows that de-extinction is not just scientifically complicated, but ethically complicated too.