The genomes of many non-African humans today have this sequence, which includes a cluster of genes that code for Toll-like receptors, or TLRs—a type of immune protein that sniffs out pathogens. And it turns out that archaic variants of that gene are associated with lower microbial loads in present-day humans—a trait that may have been quite valuable to our ancestors as they settled new lands. The study appears in the American Journal of Human Genetics. [Dannemann et al, Introgression of Neandertal- and Denisovan-like Haplotypes Contributes to Adaptive Variation in Human Toll-like Receptors]