Correspondence of fat intake with civilisatory diseases (coronary disease and cancer) is usually attributed to adverse effects of animal fat and cholesterol. The 'field studies' themselves, undertaken to support this theory, failed. As the last environmental changes in human history are agriculture and rise of carbohydrate intake (and concomitant reduction of fat and protein consumption), the author thinks that the carbohydrates rather than the animal fats cause our civilisatory diseases. It can be shown that the spread of agriculture from the Near East to the West and North of Europe with the accompanying differences in time for the adaptation to the new food (the carbohydrates) easily explains the geographic differences in the frequency of civilisatory diseases which is highest where (in Northern Ireland, Scotland and Finland) carbohydrates came last. Highest, too, in those areas is the 'polymorphism' of genes which are related to cardiovascular diseases (ACE, apolipoprotein-B etc.) This 'adaptation theory' explains also the hitherto unexplained up and down of cardiovascular disease in the USA by immigration from regions with higher adaptation to carbohydrates.