Figure 2

Schematic phylogeny in primates and classification of differentially expressed genes between humans and chimpanzees. (1) Diversified group: gene expression levels in the three species are significantly different from each other. (2) Chimpanzee lineage (L_C)-specific group: gene expression in the orangutan is significantly different from that in the chimpanzee but not from that in the human. Gene expression is induced ( I) if b > a, or is repressed (R) if b < a in the chimpanzee lineage. (3) Human lineage (L_H)-specific group: gene expression in the orangutan is significantly different from that in the human but not from that in the chimpanzee. Gene expression is induced (I) if b > a, or is repressed (R) if b < a, in the human lineage. (4) Unclassified group: expression in the orangutan is not significantly different from that in both chimpanzee and human. The gene expression level is characterised as a, b, c and a', where a/a', b and c are significantly different and a and a' are not.