Thursday, November 20, 2008

How to clone a woolly mammoth

1) Buy extinct mammal hair from eBay; 2) Produce DNA sequence; 3) Artificially inseminate elephant; 4) Cook till term


You wait 10,000 years, and then two come at once. Bigger than buses, woolly mammoths have stampeded into the headlines for the second time in a fortnight. Earlier this month, the press trumpeted the possibility of resurrecting the long-dead hairy beast after scientists cloned mice from tissue that had been sitting in a freezer for 16 years. It was a glib throwaway remark that sparked this coverage, but now we can address this question directly.

Today, Mammothus primigenius joins the genome club, that exclusive but expanding zoo of creatures that have had their genetic recipe decoded. Its illustrious colleagues include humans, mice, the honeybee, the fruit fly and the absurd platypus, all for very worthy reasons. Uniquely, this newest member is utterly extinct. Reading the 4bn letters of mammoth DNA is a monumentally cool piece of research, not just because the specimens have been buried in permafrost for millennia. As a proof of principle it's brilliant science. It also tells us much about the evolution of elephants. And if you like your science practical, it reveals new data for contemporary conservation. Because we have a genetic handle on a species that went extinct (without human intervention, as one of the types of mammoth did), we are given a new understanding of how variation in genes within species relates to extinction.

I suspect, though, that the media will again focus on the question of cloning. Let's play to the crowd and address this issue, because it is that thing that science doesn't always do terribly well: fun.

What would you need? Well, step one is to produce the complete DNA sequence, broken up into chunks called chromosomes. Already, we epically fail. The new sequence is far from perfect – they rarely are – and needs much refining before being accurate enough to avoid horrific effects on any potential clone. That would be an issue if the complete genome existed anywhere other than in silico, that is, on a computer screen. In the tissue, the DNA is hopelessly fragmented, mostly because dead mammoths freeze slowly, rather than taking the plunge into liquid nitrogen as you would in the in the lab. As it is, we don't even know how many chromosomes woolly had. Assuming it's 56, like living elephants, we have to get those chromosomes into a donor egg cell from an elephant. Again this is no mean feat. An elephant's ovaries are some 7ft from any, erm, access point, and adult females ovulate infrequently. Fortunately, mice exist that artificially harbour elephant ovarian tissue, so we can bypass that rather invasive procedure, albeit temporarily. Alas, once the mammoth genome is safely in the egg, we have to get it back into the surrogate mother. Believe it or not, this has been done for artificial insemination. I shall refrain from further detailing this uncomfortable journey to the centre of an elephant. But it's quite a trip.

Now just cook till term. We don't know how long that would be. If pregnancy were successful, we've got all the issues of a presumably surprised elephant giving birth to a somewhat hairier calf. Then there's the mammoth ethical problem of bringing to life an animal that has neither habitat nor kin.

There's a second part to this story, that isn't reported in the paper. The tissue from which the sequence was generated came from mammoth hair that had been lying in icy Siberian graves for thousands of years. But this chapter of their story started much closer to home. Stephan Schuster's team from Penn State University spent absolutely no time in the deep freeze. They initially got their hair samples from eBay, the successful bid being $130. A quick search at the time of writing shows four mammoth hair lots going, the cheapest being 99p (plus p&p).

This is the tip of the iceberg in terms of fossil trading. Schuster warns that unless you can absolutely verify exactly what you are buying, then you really shouldn't: you are potentially reinforcing a black market that serves neither science nor humankind. His team proceeded with extreme caution, verifying the credentials of the seller, verifying that he had the right licences and permits to sell samples that were legally obtained, and legally imported. Don't buy DVDs off men in pubs, and unless you really know what you're doing, don't buy fossils from eBay.

This shaggy elephant story has fantastic science and an accompanying cautionary tale. Bringing back the woolly mammoth must remain the stuff of dreams for now. We're still a long, long way from Pleistocene Park, let alone Jurassic Park. Nevertheless, today we are one step – or 4 billion letters – closer than we were. It's a word whose colloquial use betrays its literal meaning, but this latest chapter in the story of evolution is truly awesome.


At 6:53 PM, Blogger Frank Partisan said...

The Ebay link in the story was what hippies called a downer. Some things you don't buy on Ebay.


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