Scientists have made a groundbreaking discovery about the human genome, revealing that ancient viral DNA may play a powerful role in regulating gene expression. A new study published in Science Advances suggests that certain sequences of DNA, known as transposable elements (TEs), were once thought to be “junk” but actually act like genetic switches.
These TEs originated from ancient viruses and have spread throughout the genome over millions of years through a process called copy-and-paste. Today, they make up nearly half of the human genome. However, studying these repetitive sequences has been challenging due to their highly similar nature.
To overcome this limitation, researchers developed a new method for classifying TEs based on evolutionary relationships and conservation in primate genomes. This approach allowed them to identify four distinct subfamilies of MER11 sequences, which they tested using a technique called lentiMPRA.
The results showed that one of the subfamilies, MER11_G4, had a strong ability to activate gene expression and even contributed to shaping what makes humans different from other primates. This sequence has evolved to act like a tiny genetic switch, controlling how genes are turned on or off, especially during early human development.
The study provides new insights into the evolution of “junk” DNA and its potential role in regulating gene activity. By tracing the evolution of these sequences and directly testing their function, researchers have demonstrated how ancient viral DNA has been co-opted into shaping gene activity in primates.
Source: https://www.sciencedaily.com/releases/2025/07/250720034029.htm