Asked by: Nathan Allison, Yorkshire
The oldest DNA fragments recovered are only 800,000 years old, so dinosaur cloning is probably impossible. True cloning also requires an intact, living cell and it has only ever been successful using a host animal of the same species. That rules out mammoth cloning too.
What we might be able to do is splice some mammoth genes into the DNA of the Asian elephant, their closest relative. Most of the mammoth genome has already been sequenced from fragments recovered from mammoths frozen in the Siberian permafrost. Last year, a team at Harvard managed to insert 14 mammoth genes into an elephant cell in a petri dish. But Asian elephants and mammoths are thought to differ by at least 400 genes, and figuring out exactly which ones are different will take a while. And then that single cell still needs to develop into an embryo and then a baby mammoth.
We don’t know enough about elephant reproduction to even manage ordinary in vitro fertilisation (IVF) yet, and the success rate of implanted cloned cells is so low that it would be impractical and unethical to try this with elephant surrogate mothers. We may be able to make progressively more mammoth-like elephant hybrids, but it will be a slow process.