Different signatures of natural selection persist over varying time scales in our genome, revealing possible episodes of adaptative evolution during human history. Here, we identify genes showing signatures of ancestral positive selection in the human lineage and investigate whether some of those genes have been evolving adaptatively in extant human populations. Specifically, we compared more than 11,000 human genes with their orthologs in/nchimpanzee, mouse, rat and dog and applied a branch-site likelihood method to test for positive selection on the human lineage. Among the significant cases, a robust set of 11 genes were then further explored for signatures of recent positive selection using SNP data. We genotyped 223 SNPs in 39 worldwide populations from the HGDP Diversity panel and supplemented this information with available genotypes for up to 4,814 SNPs distributed along 2 Mb centered on each gene. After exploring the allele frequency spectrum, population differentiation and the maintainance of long unbroken haplotypes, we found signals of recent adaptative phenomena in only one of the 11 candidate gene regions. However, the signal of/nrecent selection in this region may come from a different, neighbouring gene (CD5) rather/nthan from the candidate gene itself (VPS37C). For this set of positively-selected genes in the/nhuman lineage, we find no indication that these genes maintained their rapid evolutionary/npace among human populations. Based on these data, it therefore appears that adaptation for/nhuman-specific and for population-specific traits may have involved different genes.

This work was supported by Dirección General de Investigación, Ministerio de Educación y Ciencia, Spain [BFU2005-00243 and BFU2008-010406/BMC to E.B.] and by the Direcció General de Recerca, Generalitat de Catalunya [2005SGR00608 to J.B]. A Moreno-Estrada was supported by a fellowship from the Consejo Nacional de Ciencia y Tecnología (CONACyT), México and received a travel /ngrant from the Boehringer Ingelheim Foundation, Germany. SNP genotyping services were provided by the Spanish “Centro Nacional de Genotipado” (www.cegen.org).