On 2013 Nov 08, Tomislav Maricic commented:

We, who are authors of this publication, are not aware of any modern human contamination over and above that which is clearly quantified and reported in our manuscripts. We have developed and published a number of approaches to quantify modern human contamination using both mitochondrial and nuclear sequence data (Green RE, 2008, Green RE, 2009, Meyer M, 2012). In each paper where we report DNA sequences from archaic humans we have carefully quantified and reported any modern human contamination detected. In the case of this paper, the alleles studied are derived in almost all modern humans and differ from both the Neandertal and Denisovan genomes (which both carry the ancestral allele). This is itself unlikely to be consistent with modern human contamination of the archaic samples. Finally, it is difficult to respond to rumors without knowing the substance of the analyses on which such rumors are based. We would be interested to see the data and analyses that suggest modern human contamination. -Tomislav Maricic, Matthias Meyer, Janet Kelso, Svante Paabo

On 2013 Oct 28, Steven Salzberg commented:

I heard a rumor very recently that the contamination problem, discussed cogently after the first Neanderthal papers (see http://www.ncbi.nlm.nih.gov/pubmed/17937503), has arisen again, and that the authors are now aware of the very real likelihood that modern human DNA is contaminating these samples. If true, this would invalidate the analysis of FOXP2 and the multiple other papers about this genome. What do the authors have to say?

On 2013 Oct 28, Steven Salzberg commented:

I heard a rumor very recently that the contamination problem, discussed cogently after the first Neanderthal papers (see http://www.ncbi.nlm.nih.gov/pubmed/17937503), has arisen again, and that the authors are now aware of the very real likelihood that modern human DNA is contaminating these samples. If true, this would invalidate the analysis of FOXP2 and the multiple other papers about this genome. What do the authors have to say?