Figure 5.

Autoimmunity and the evolutionary genetics of encephalization and cognition. It is suggested that evolution of the Foxp1/2/4 genes have not only contributed to a diversification of neural repertoire but have instructed what could be called a “speciation” of such repertoire i.e., the acquisition of species-specific features. In parallel, evolution of the MHC class II genes have contributed to the diversification and “speciation” of the T-cell repertoire, notably the autoreactive T-cell repertoire directed against brain superautoantigens. Finally, evolution of the Foxp3 gene may have allowed a species-specific control of cognition-promoting autoimmunity. These combined mechanisms would support an endogenously-driven and species-specific processes which would shape encephalization and cognition. By this mean, external cues exerting a selection pressure on a given species would be filtered by the internally-fueled sensing skills of this species. In turn, perceived externals cues would further instruct the diversification and speciation of the neural and T-cell repertoires.