Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (2006), “Genetic evidence for complex speciation of humans and chimpanzees”, Nature, 441 (7097): 1103–8, doi:10.1038/nature04789, PMID16710306
Wakeley J (2008), “Complex speciation of humans and chimpanzees”, Nature, 452 (7184): E3–4, doi:10.1038/nature06805, PMID18337768 "Patterson et al. suggest that the apparently short divergence time between humans and chimpanzees on the X chromosome is explained by a massive interspecific hybridization event in the ancestry of these two species. However, Patterson et al. do not statistically test their own null model of simple speciation before concluding that speciation was complex, and—even if the null model could be rejected—they do not consider other explanations of a short divergence time on the X chromosome. These include natural selection on the X chromosome in the common ancestor of humans and chimpanzees, changes in the ratio of male-to-female mutation rates over time, and less extreme versions of divergence with gene flow. I therefore believe that their claim of hybridization is unwarranted."
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pubmed.ncbi.nlm.nih.gov
Patterson N, Richter DJ, Gnerre S, Lander ES, Reich D (2006), “Genetic evidence for complex speciation of humans and chimpanzees”, Nature, 441 (7097): 1103–8, doi:10.1038/nature04789, PMID16710306
Wakeley J (2008), “Complex speciation of humans and chimpanzees”, Nature, 452 (7184): E3–4, doi:10.1038/nature06805, PMID18337768 "Patterson et al. suggest that the apparently short divergence time between humans and chimpanzees on the X chromosome is explained by a massive interspecific hybridization event in the ancestry of these two species. However, Patterson et al. do not statistically test their own null model of simple speciation before concluding that speciation was complex, and—even if the null model could be rejected—they do not consider other explanations of a short divergence time on the X chromosome. These include natural selection on the X chromosome in the common ancestor of humans and chimpanzees, changes in the ratio of male-to-female mutation rates over time, and less extreme versions of divergence with gene flow. I therefore believe that their claim of hybridization is unwarranted."