Downregulation of the human gene FCGR2B, which provides protection against infection, alleviates ARDs [117,118] and matches downregulation of the homologous genes Fcer2, Fcgr2b, Fcgr3a, Fcgr3b, Fcrl1, and Fcrl2 in wild rabbits [206], aggressive rats [68,204], and aggressive foxes [208] after they and their domestic conspecifics split from their most recent common ancestor (Table 9). This evidence concerns the gene FCER2 and infection.