Complementary ways of meeting the world’s protein need

Before considering the various possible protein sources, we must make some sort of estimate of the possible protein need by—say—the end of the century. That estimate controls the amount of effort we should put into work on protein supplies and the degree of novelty that we should envisage. The estimate depends on the number of people to be fed and the amount of protein that each needs. Both quantities are uncertain: the first because it must be guessed, the second because it is hotly disputed.