[chargrilled]

It's a shame the original paper seems to be stuck behind a journal paywall.

Does anyone have access to a preprint?

[chapmanb]

The PDF is currently available, although I couldn't find a direct link so it may be a temporary mistake:

http://www.sciencemag.org/content/334/6062/1518.full.pdf

Supporting online material:

http://www.sciencemag.org/content/suppl/2011/12/14/334.6062....

[chargrilled]

I get a "Subscribe/Join AAAS or Buy Access to This Article to View Full Text." for the PDF page.