The evolution of all animals can be attributed to certain viruses infecting primitive organisms hundreds of millions of years ago. The genetic material of the virus has been integrated into the genome of the first multicellular organism and still exists in human DNA to this day. In the new issue of the journal Scientific Progress, scientists from the Spanish National Cancer Research Center have for the first time described the role these viruses play in life processes crucial to human development. This process occurs a few hours after fertilization: when the oocyte transforms from two cells to four cells, it becomes pluripotent. Before this step, both cells of the embryo are omnipotent, meaning they can develop in an independent organism; The four cells in the next stage are not omnipotent, but multipotent, as they can differentiate into cells of any specific tissue in the body. Genetic material from endogenous retroviruses is integrated into the genome of organisms, which may have been a driving factor for the Cambrian biodiversity outbreak. In the past decade, it has been found that the gene sequences of these viruses account for at least 8-10% of the human genome. These viral residues were once considered junk DNA. However, in recent years, scientists have begun to realize that these retroviruses, which have co evolved with humans for millions of years, have important functions, such as regulating genes. A new study suggests that an endogenous MERVL retrovirus determines the rate of embryonic development, particularly in specific steps of transition from pluripotency to pluripotency. Researchers have discovered a new mechanism that can explain how endogenous retroviruses directly control pluripotent factors. This new mechanism involves the URI gene. Years ago, it was discovered that if the URI in the body of experimental animals was deleted, embryos could not even develop. New research suggests that one of the functions of a URI is to activate the molecules necessary for achieving pluripotency. If the URI does not work, the pluripotency factor also does not work. It has been proven that an endogenous retroviral protein MERVL gag can regulate the function of URI. Research has found that during the pluripotent phase, when there are only two cells in the oocyte, the expression level of MERVL gag virus protein is high. This protein binds to URI and prevents its function. However, as the level of MERVL gag virus protein decreases, URI begins to take effect, exhibiting pluripotency. The most crucial aspect of this new study is that it reveals the symbiotic evolution between endogenous retroviruses and their host cells, ensuring the smooth development of early embryos. In other words, the three-dimensional relationship between viral proteins, URI, and pluripotent factors is finely regulated, allowing the embryo enough time to adjust and coordinating a smooth transition from pluripotency to pluripotency during embryonic development. It is precisely all of this that makes this great history of tissue and organ cell development more standardized. (Lai Xin She)