Ruminants: Evolutionary past and future impact

Ruminants are mammals of considerable agricultural, conservational, and biomedical importance. The approximately 200 extant species of this clade include traditional livestock such as cattle and sheep, endangered species such as Père David's deer or milu, and species of biomedical interest, such as antlered deer (1–8). Ruminants are extremely diverse but share in common a multichambered stomach specialized for digesting tough plant fibers through microbial-aided fermentation (1, 4). Collectively, ruminants are highly successful, having colonized multiple terrestrial environments, including the unforgiving conditions of the Arctic tundra (3, 4). On pages 1152, 1153, and 1154 of this issue, Chen et al. (1), Wang et al. (2), and Lin et al. (3), respectively, sequenced the genomes of multiple ruminant species, offering resources and analyses for understanding their evolution and diversity. The findings provide vital insights into genetic adaptations that are responsible for their biological success, as well as how they have been affected by human activity.