There is only partial agreement on these results.  For a bit more, see:  <a href="http:&#x2F;&#x2F;www.sciencemag.org&#x2F;content&#x2F;349&#x2F;6246&#x2F;354.summary?sid=c8a040a2-e527-4b4e-bfcb-9e486acf6338" rel="nofollow">http:&#x2F;&#x2F;www.sciencemag.org&#x2F;content&#x2F;349&#x2F;6246&#x2F;354.summary?sid=c...</a>