Unrooted H1 phylogeny. H1.0 (H1°) is an animal-specific clade, including avian H5. H1.10 (H1x) is found in vertebrates. Mammal-specific clades include H1.7 (H1T2) and H1.9 (Hils1). H1.8 (H1oo) and H1.6 (H1t) are also monophyletic in mammals, but other TS H1s and oocyte H1s are not clearly members of the same clades.