In Nature this week, a Max Planck Institute-led team reports the results of a genome-analysis study suggesting that early modern humans and Neanderthals may have interbred far earlier than previously believed. The researchers analyzed the genomes of a Neanderthal and a Denisovan from the Altai Mountains of Serbia as well as hundred of African genomes. They also studied sequence data from chromosome 21 of two additional Neanderthals from different regions of Europe. The group found evidence of gene flow from a population that diverged early from other modern humans in Africa to the ancestors of Neanderthals from Altai around 100,000 years ago. They did not, however, detect a genetic influence in the Denisovan or the other European Neanderthals. GenomeWeb has more on this here.
And in Nature Genetics, a pair of researchers from the University of Pennsylvania presents a new model to explain variability on polymorphism level across the human genome. While previous studies have examined polymorphism levels across the genome by focusing on the immediately flanking nucleotides around a polymorphic site, the researchers combined a novel statistical framework with data from the 1000 Genomes Project to show that a heptanucleotide context explains more than 80 percent of variability in substitution probabilities. The approach also identified previously undiscovered variability in C-to-T substitutions at CpG sites, which is not immediately explained by differential methylation intensity. The researchers further show the clinical applicability of their model in neuropsychiatric disease.