Cows and other cattle are subject to a number of diseases, but most recent concern has been focused upon bovine spongiform encephalopathy, also known as mad cow disease. First recognized in 1986, the disease, which is similar to a neurodegenerative disorder that sometimes occurs in sheep, is generally believed to have developed when cattle were fed animal-derived protein supplements. Apprehension that that the condition could be transmitted to humans led to a heightened interest in closely monitoring the diet of cows, and this interest has led to an important breakthrough. Recently, a German scientist utilized the established technique of isotopic analysis to examine the hair of cows, enabling him to reconstruct the animals’ entire environmental and dietary history.