Hi all --
Here is an interesting article about olfaction recently published by Yoshihito Niimura in Current Genomics: "Olfactory Receptor Multigene Family in Vertebrates: From the Viewpoint of Evolutionary Genomics." Niimura gives a general overview of the evolution of olfaction in vertebrates. Importantly, he finds that higher primates and other mammals with well-developed vision systems have a smaller number of olfactory receptor (OR) genes. He also notes that there are about 400 OR genes in the human genome, forming the largest multi gene family.