It occurred to him that cats in the wild did not cook their food; perhaps cats had a digestive system that couldn't process or assimilate much out of cooked food. Perhaps the problem he had been having was not because the cats were without adrenal glands but because they were without sustenance, suffering a sort of slow starvation in the midst of plenty. So Dr. Pottenger set up some cat feeding experiments. There were four possible combinations of his regimen: raw meat and unpasteurized milk; raw meat and pasteurized milk; cooked meat and raw milk; cooked meat and pasteurized milk, this last one being what he had been feeding all along. So he divided his cats into four groups and fed each group differently. The first results of Pottenger's experiments were revealed quickly though the most valuable results took longer to see. The cats on raw meat and raw milk did best. The ones on raw meat and pasteurized milk did okay but not as well. The ones on cooked meat and raw milk did even less well and those on all cooked food continued to do as poorly as ever. Clearly, cats can't digest cooked food; all animals do better fed on what they can digest. A lot of people have taken Pottenger's data and mistakenly concluded that humans also should eat only raw food. This idea is debatable. However, the most important result of the cat experiments took years to reveal itself and is not paid much attention to, probably because its implications are very depressing. Dr. Pottenger continued his experiments for several generations. It was the transgenerational changes that showed the most valuable lesson. Over several generations, the cats on all raw foods began to alter their appearance. Their faces got wider, their pelvic girdles broader, bones solider, teeth better. They began to breed very successfully. After quite a few generations, the healthiest group, the one on all raw foods, seemed to have improved as much as it could. So Dr. Pottenger took some of these cats and began feeding them only cooked food to study the process of nutritional degeneration. After three "de"generations on cooked fodder the group had deteriorated so much that the animals could barely breed. Their faces had become narrow, their teeth crooked, their pelvic girdles narrow, their bones and body structure very small, and their dispositions poor. Mothers wouldn't nurse their young and sometimes became cannibalistic. They no longer lived very long. Before the degenerating group completely lost the ability to breed, Pottenger began to again feed them all raw food. It took four generations on a perfect, raw food diet before some perfect appearing individuals showed up in the group. It takes longer to repair the damage than it does to cause it and it takes generations of unflagging persistence.