You probably use your iris or face to unlock your phone dozens of times a day. Biometrics—the science of measuring unique biological features—is the gold standard for secure identification in the human world. But did you know that this same cutting-edge science has been adapted to the animal kingdom, not just to track cattle, but to ensure fairness in one of the oldest and most high-stakes sports on Earth? Welcome to the hidden world of tamper-proof security for the elite ath