As mentioned above, this will be illustrated with the FoxP2 case. Studies in individuals with hereditary linguistic deficits have led to the identification of a mutation in the
coding sequence of FoxP2 . 12,14,15 This gene is present in all vertebrates, not only in humans, and its coding sequence is highly conserved. Despite Inhibitors,research,lifescience,medical this conservation, the chimpanzee and human genes differ by two nonsynonymous substitutions that probably appeared less than 200 000 years ago. It was thus proposed that these mutations may have participated in the appearance of human language.16 The human version of the gene influences Inhibitors,research,lifescience,medical the development and the function of several brain regions associated with the selleck chemicals llc learning and production of speech sequences. Also, and most importantly, in the control and fine tuning of the delicate motor tasks that accompany articulate languages.17 These point mutations may thus have contributed to the exceptional
linguistic fluidity that characterizes our species. It is established that they reduced the separation between Inhibitors,research,lifescience,medical Neanderthals and modern humans, suggesting that our close cousins who disappeared 30 000 years ago had mastered some sort of articulate language. Gene networks, gene copies, and energy in the brain We will now leave aside point mutations in coding sequences, and develop a few examples of modifications in gene regulatory sequences. It is impossible to go into great detail here; the interested Inhibitors,research,lifescience,medical reader should consult the specialized literature on the genes and regulatory
elements that have evolved separately in the chimpanzee and human lineages since they separated. Here, a few facts regarding the brain will be discussed. First, there is the fact that individual genes matter less than gene networks, which vary synchronously in specific brain regions. These networks can be seen as homeostatic devices in the sense that any modification Inhibitors,research,lifescience,medical in the rate of expression of one gene in the network will be “buffered” by the others. Genetics is like physiology (is physiology!) as, at equilibrium, PAK6 it only transiently allows extreme variations to take place. On this basis, several modules of coregulated genes can be defined in distinct brain regions, with some of them differing between the two species.18,19 Investigators identified a module specifically present in the human, and thus of high interest from an evolutionary viewpoint. A rapid survey of the genes composing this “human module” shows that they encode proteins that regulate energy metabolism, the distribution and morphology of mitochondria, neuronal shape, and neurotransmitter secretion.