Digital doppelgängers just developed a pulse. Researchers hunting deepfakes long relied on a seemingly foolproof detection method: AI couldn’t fake the subtle skin color changes caused by your pulse. That certainty has now collapsed, as scientists discover modern deepfakes inadvertently preserve the heartbeat patterns from their source videos, making our most trusted detection tools suddenly unreliable.

For years, cybersecurity experts thought they had deepfakes all figured out. Since AI wasn’t explicitly programmed to mimic subtle color changes in human skin caused by blood flow, researchers believed fake videos would lack these physiological signals. But according to a new international study published in the journal Frontiers in Imaging, that defense has now crumbled.