Since the fifties of the 20th century, intensive breeding in livestock has increased sharply. An increase that keeps pace with the recent increase in cancer mortality.In the past many large and small mammals have been domesticated. The population has acquired immunity against the great epidemics of the past. Zoonotic infections like the black plague, smallpox, tuberculosis, measles, typhoid and cholera could be treated with vaccination and antibiotics.Since the middle of the twentieth century we have a new situation, caused by intensive farming. All meat of farmed mammals is only produced by manual insemination of cattle, pigs and rabbits. Mad cow disease, swine fever and bird flu are the result of intensive livestock farming.The population explosion and famine on earth have caused man to artificially inseminate animals and to breed exclusively for consumption. Fast food and an increase in meat consumption in the West are simulated in other parts of the world. Fast food, unnatural food and hamburger consumption lead to obesity and chronic diseases. In the meantime, the number of cancer diseases is increasing and is nowadays prime cause of chronic diseases and premature death in the elderly. The ceiling for meat and meat products has already been reached with the current 7 billion world population. The production of meat (products), poultry, pork and other meat tripled between 1980 and 2010 and is expected to double again in 2050.Global warming is largely the result of intensive livestock production. During the last ice age man was forced to eat more meat because there were fewer grains, fruits, nuts and seeds. Will modern man eat more vegetable food now that the earth is warming up?