Telegraph: Thomas Malthus’s Essay on the Principle of Population, published in 1798, had a subtle argument and an alarming conclusion. Improvements in food production would lead to population growth; growing populations would also lead to increases in food production; but of these two lines of growth, one (population) would be much steeper than the other. And once they were far apart, only famine, disease and war would bring them back together. When Malthus wrote his book, the world’s population …