Archaeochronology seeks to establish absolute or relative dates for archaeological or paleoanthropological events. Therein, the scale, or the temporal resolution attainable, changes dramatically over the total time for human cultural and biological evolution. For radiometrically based dating methods, the half life (half lives) isotopic abundances, and contamination limit the intrinsic dating range, whereas factors, such as radiation dose, saturation effects, diffusivity, and chemical rates, limit other absolute archaeochronometers. As technology improves, however, precision usually increases, while the intrinsic dating limit can often be extended, thereby enhancing the scale. Even were the dating methods significantly more precise, contamination or sample degradation often further restrict a method's utility, while the number of sites preserved diminishes the older they are. Moreover, the archaeological "distinctiveness" decreases, perhaps due to the imprecision in the dating methods, but possibly, because the tempo in human cultural and biological evolution has incrased exponentially. Increasingly finer archaeochronological scales have significantly altered archaeological paradigms, in all phases of hominid biological and cultural evolution from African Australopithecus' skeletons to North American Homo sapiens sapiens' longhouses. While multiple concordant dates may resolve the dating problem presented by a single method, often sample instability affects all the applicable methods. Frequently, relative methods can constrain the absolute date. The accuracy for any new method or a new application to different sample materials must be rigorously tested under controlled conditions for concordancy with other established methods. Concordancy tests, intraand intersite correlation all require extensive knowledge about the inherent limitations in the different methods. Ultimately, it rests with the archaeologist to thoroughly understand those limitations, and the archaeochronologist to fully understand the archaeological problems.