In this context, "biometrics" is the "automatic identification or identity verification of living, human individuals based on physiological and behavioral characteristics". Biometrics is a subset of the larger field of human identification science. The term "automatic" in the definition means that digital computers will usually (but not always) be used. We consider the general state of digital signal processing in biometrics by examining the computational approaches to speaker, fingerprint, and face recognition. We note the generally weak relationship between physiology and biometric "features" and the potential for use of "models" to compensate for intra-class variation.