Not the right DOI, but this article from last year covers the same territory: http://www.pnas.org/content/106/30/12323.full http://www.pnas.org/content/106/30/1

Not the right DOI, but this article from last year covers the same territory: http://www.pnas.org/content/106/30/12323.full http://www.pnas.org/content/106/30/12323.full The article from the current issue that best matches the discussion in the ARS article is here: http://www.pnas.org/content/107/9/4051.abstract?sid=dfaf11ad-e71a-4973-8636-774a744c717e http://www.pnas.org/content/107/9/4051.abstract?sid=dfaf11ad... Can't find the article cited at the DOI link is broken.