I just finished Warren Belasco's book Meals to Come: A History of the Future of Food and it is truly astounding how many people believed that humans would be vegetarians by necessity at the end of the twentieth century. Looking at this prediction from 1926, it is interesting to see that per capita pork consumption declined while beef consumption rose drastically.
"Alonzo Taylor, director of Stanford University's Food Research Institute, represented mainstream nutritional opinion in 1926 when he projected a U.S. population of 175 million in 1980 (actual: 226 million) and forecast a likely reduction of per capita beef consumption from 68 pounds in 1926 to 50 in 1980 (actual: 95), and a reduction of pork consumption from 90 lbs to 64 (actual 55). While such intakes were more than adequate, he concluded, even further livestock reductions would be required if the U.S. population ever reached an unimaginable 200 million."
The Population Bomb: Scenario 1 (1970) 12 March 2007
The Population Bomb: Scenario 2 (1970) 21 March 2007
A Glimpse of the Year 2000 (New York Times, 1982) 26 Feb 2007