The news that South Korean scientists are planning to clone a mammoth, using the DNA of a particularly well-preserved specimen in the Siberian permafrost, has reignited the debate over the ethics of cloning. But whether or not it’s right, could it happen? And what other animals could, or couldn’t, we clone?
It may be possible to clone a mammoth. It would be an enormous technical challenge, because the freezing process which preserves the dead animals also tears up the cells. Normal cloning techniques – such as that which produced Dolly the Sheep – involve taking the whole cell from the animal being cloned, and allowing it to divide in a petri dish with an egg cell which has had the DNA removed. When the cell is torn apart by the ice crystals which form during freezing, that can’t work.
However, scientists have successfully cloned a mouse which had been frozen for 16 years by using a different technique: taking the DNA-containing nucleus out of the cell to be cloned, and injecting that directly into a denucleated egg cell. That suggests that, in principle, the same could be done for a mammoth. However, there are huge obstacles: for a start, the DNA will have degraded over the millennia since the mammoth was frozen, and while the scientists could freeze as many mice as they liked and use thousands of cells for their purposes, there is an extremely limited number of mammoths available to work with.