Could we 'de-extinctify' the woolly mammoth?

A team from Harvard made headlines by announcing it had put mammoth DNA into elephant cells. But should we 'de-extinctify' the beasts and return them to their old stamping grounds?

Extinction, it seems, may no longer be for ever. Several weeks ago, scientists in George Church's lab at Harvard University announced that they had created living elephant cells that contained a small component of synthesised mammoth DNA. The announcement stirred both excitement and concern that the mammoth - a hairier cousin of the Asian elephant - might soon be back from the dead. But how close are we really to seeing resurrected mammoths wandering their old stamping grounds, including the Norfolk countryside? The answer depends on how you define mammoth.

Let's begin by laying out what resources we have today. First, scientists who study the genetics of extinct species have recently decoded most of the mammoth's genome sequence, which means we have a pretty good genetic blueprint for making a mammoth. Second, by comparing the mammoth genome sequence to the elephant's, we are beginning to understand how, at the level of their DNA, mammoths and Asian elephants differed. This tells us what parts of the elephant genome we will need to change in order to make a mammoth. Third, recent advances in genome engineering technologies provide a powerful toolkit for editing genomes, including cutting out and replacing specific genes. And fourth, the work at Harvard has proved that these tools can be used to insert mammoth DNA into an elephant cell. Resurrected mammoths no longer seem the stuff of fantasy.

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