It is by estamination that ERV integrates into host cells and settles there about 120 million years ago, and ERV may play an important role in the evolution, pathology and physiology of animals.

• ERV大约在约1.；2亿年前入侵动物细胞并在动物体内定居，其在哺乳动物的进化中扮演了非常重要的角色。