By the 1960s, the nature versus nurture controversy had largely subsided. Both ethologists and psychologists realized that a sharp distinction between instinct and learning was misleading. Almost all forms of behavior involved both elements. Tinbergen himself pointed out that four different questions could be asked about behavior. How was it caused by nerves and hormones? How did it develop in the growing organism? How was it adaptive in a particular environment? And how had it evolved? These questions were equally important, but a single scientist might not be able to answer all of them. Studying each question required a different set of methods and, perhaps, a slightly different perspective on what was important about animal behavior.