PARC researcher, Sarah Tishkoff's research Limits of long-term selection against Neandertal introgression was reported in a Penn Today article. Tishkoff works with former research associate Laura Scheinfeldt and former grad student Sameer Soi,to offer a new look at African genetic diversity, with data from 50 populations. Among other insights, their analysis suggests that hunter-gatherer groups, a few of whom speak languages involving clicks, share a common ancestry despite being geographically far-flung.