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\n The human genome is made up of 23 pairs of chromosomes, the biological blueprints that make humans \u2026 well, human. But it turns out that some of our DNA \u2014 about 8%<\/a> \u2014 are the remnants of ancient viruses that embedded themselves into our genetic code over the course of human evolution.\n <\/p>\n \n These ancient viruses lie in sections of our DNA called transposable elements, or TEs, also known as \u201cjumping genes\u201d due to their ability to copy and paste themselves throughout the genome. TEs, which account for nearly half of our genetic material, were once waved off as \u201cjunk\u201d DNA, sequences that appear to have no biological function. Now, a new study offers support for the hypothesis that these ancient viral remnants play a key role in the early stages of human development and may have been implicated in our evolution.\n <\/p>\n \n By sequencing TEs, an international team of researchers identified hidden patterns that could be crucial for gene regulation<\/a>, the process of turning genes on and off. The findings were published July 18 in the journal Science Advances<\/a>.\n <\/p>\n \n \u201cOur genome was sequenced long ago, but the function of many of its parts remain unknown,\u201d study coauthor Dr. Fumitaka Inoue, an associate professor in functional genomics at Kyoto University in Japan, said in a statement<\/a>. \u201cTransposable elements are thought to play important roles in genome evolution, and their significance is expected to become clearer as research continues to advance.\u201d\n <\/p>\n \n There are many benefits to studying how TEs activate gene expression. It could help scientists understand the <\/strong>role <\/strong>that the <\/strong>sequences <\/strong>play in human evolution, reveal possible links between TEs and human diseases, or teach researchers how to target functional TEs in gene therapy, said lead researcher Dr. Xun Chen, a computational biologist and principal investigator at Shanghai Institute of Immunity and Infection of the Chinese Academy of Sciences.\n <\/p>\n \n With more research, \u201cwe hope to uncover how TEs, particularly ERVs (endogenous retroviruses, or ancient viral DNA), make us human,\u201d Chen added in an email.\n <\/p>\n \n When our primate ancestors were infected with viruses, sequences of viral genetic information would replicate and insert themselves in various locations in the host\u2019s chromosomes.\n <\/p>\n \n \u201cAncient viruses are effective in invading our ancestral genomes, and their remnants become a big part of our genome. Our genome has developed numerous mechanisms to control these ancient viruses, and to eliminate their potential detrimental effects,\u201d said Dr. Lin He, a molecular biologist and the Thomas and Stacey Siebel Distinguished Chair professor in stem cell research at the University of California, Berkeley, in an email.\n <\/p>\n \n For the most part, these ancient viruses are inactive and are not a cause of concern, but in recent years, research has shown that some of the transposable elements may play important roles in human diseases. A July 2024 study<\/a> explored the possibility of silencing certain TEs to make cancer treatment more effective.\n <\/p>\n \n \u201cOver the course of evolution, some viruses are degenerated or eliminated, some are largely repressed in expression in normal development and physiology, and some are domesticated to serve the human genome,\u201d said He, who was not involved with the new study. \u201cWhile perceived as solely harmful, some ancient viruses can become part of us, providing raw materials for genome innovation.\u201d\n <\/p>\n \n But because of their repetitive nature, transposable elements are notoriously difficult to study and organize. While TE sequences are categorized into families and subfamilies based on their function and similarity, many have been poorly documented and classified, \u201cwhich could significantly impact their evolutionary and functional analyses,\u201d Chen said.\n <\/p>\n Ancient viral impact on human development and evolution<\/p>\n \n The new study focused on a group of TE sequences called MER11 found within primate genomes. By using a new classification system as well as testing the DNA\u2019s gene activity, researchers identified four previously undiscovered subfamilies.\n <\/p>\n \n The most recently integrated sequence, named MER11_G4, was found to have a strong ability to activate gene expression in human stem cells and early-stage neural cells. The finding indicates that this TE subfamily plays a role in early human development and can \u201cdramatically influence how genes respond to developmental signals or environmental cues,\u201d according to a statement from Kyoto University.\n <\/p>\n \n The research also suggests that viral TEs had a part in shaping human evolution. By tracing the way the DNA has changed over time, the researchers found that the subfamily had evolved differently within the genomes of different animals, contributing to the biological <\/strong>evolution <\/strong> <\/strong>that resulted in humans, chimpanzees and macaques<\/a>. \n \u201cTo understand the evolution of our genome is one way to understand what makes humans unique,\u201d said He. \u201cIt will empower us with tools to understand human biology, human genetic diseases, and human evolution.\u201d\n <\/p>\n \n Exactly how these TEs were implicated in the evolutionary process is still unclear, Chen said. It is also possible that other TEs that have yet to be identified played distinct roles in the evolutionary <\/strong>process <\/strong> of primates, he added.\n <\/p>\n \n \u201cThe study offers new insights and potential leverage points for understanding the role of TEs in shaping the evolution of our genomes,\u201d said Dr. Steve Hoffmann, a computational biologist at the Leibniz Institute on Aging in Jena, Germany, who was not involved with the study. The research also \u201cunderscores how much more there is to learn from a type of DNA once slandered as a molecular freeloader,\u201d he added in an email.\n <\/p>\n![\"New](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/08\/gettyimages-2219798179.jpg\")
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