New research has identified a gene contributing to human cognition and was under strong positive selection. Until now, the FOXP2 gene had been known to differentiate humans from other primates, and to be related with the origin of language. [Update: See also John Hawks' post on the subject]
Genetics (Published Articles Ahead of Print)
Accelerated Evolution of the PACAP Precursor Gene During Human Origin
Yinqiu Wang et al.
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide abundantly expressed in the central nervous system, and involved in regulating neurogenesis and neuronal signal transduction. The amino acid sequence of PACAP is extremely conserved across vertebrate species, indicating a strong functional constraint during the course of evolution. However, through comparative sequence analysis, we demonstrated that the PACAP precursor gene underwent an accelerated evolution in the human lineage since the divergence from chimpanzees, and the amino acid substitution rate in humans is at least seven times faster than in other mammal species resulting from strong Darwinian positive selection. Eleven human-specific amino acid changes were identified in the PACAP precursors which are conserved from murine to African apes. Protein structural analysis suggested that a putative novel neuropeptide might have originated during human evolution and functioned in the human brain. Our data suggested that the PACAP precursor gene underwent adaptive changes during human origin and may contribute to the formation of human cognition.