 Since Grafen wrote his article, however, there has been a certain shift in non-human behavioral ecology away from the phenotypic gambit and in favor of paying attention to proximate mechanisms, not simply because these enlighten whether a behavioral strategy could evolve by natural selection in any particular case, but also the nature of the fitness costs and benefits that accrue to an organism sometimes depend on how the adaptive problem they face is solved. For example, Lotem et al. (1995) appeal to the type of learning mechanism used by parenting great reed warblers to detect the presence of cuckoos in their nests: this limits how reliable their detection of cuckoo eggs can be. Similarly, Shuker and West (2004) argue that the constraints on the egg laying strategy of the parasitic jewel wasp cannot be properly understood without paying attention to the limits on the detection mechanisms the wasp uses to determine the presence or absence of other females, versus other females’ eggs in each area.