To which Alan replies: 'Please go to the slums of Mexico City, or a raft of other cities across the South, and tell this to the burgeoning population who, however relatively impoverished, used to life off their own land, in their own communities, relying on each other, and most often in healthier conditions with access to cleaner water air and without anything like the rampant crime, corruption and drugs of their contemporary existence.'
But you are not listening, Alan. Those people would not be alive without increased output of grains and other foodstuffs. The population increased from 2 billion to 6.6 billion from 1900 to 2010. World grain output rose from 400 million tons in 1900 to 1.9 billion tons in 1998 - without that, those 4.6 billion would either have starved, or never been born.
When I said that they had better lives than they would have without increased productivity in agriculture, I was taking it as read that it is better to be alive than dead. Is it really your position that people would have been better off not being born?
As to increased agricultural productivity, either relative to land or people, there really is no question that has increased over the last 110 years. It is not a question of maligning the sources, it is recorded fact. (I don't think Michael says that it didn't happen, he puts a question mark over the calculation, which is not the same thing.)
We know that agricultural productivity increased because more food is grown while proportionally fewer people work in agriculture, and (since 1981) on a declining share of the land.
Again you pooh-pooh cheaper food and insist that it is unhealthy, but statistics of rising life expectancy and declining infant mortality, not just in the west but in the developing world, show that people are, on the average, healthier today than they were in 1900.
You trumpet Marx over population, but fail to note that his singular contribution to the population debate was to rubbish Malthus' 'libel against the human race' that overpopulation would lead to starvation.
This is Marx on population: 'the "principle of population," slowly worked out in the eighteenth century, and then, in the midst of a great social crisis, proclaimed with drums and trumpets as the infallible antidote to the teachings of Condorcet, &c., was greeted with jubilance by the English oligarchy as the great destroyer of all hankerings after human development. ' http://www.marxists.org/archive/marx/works/1867-c1/ch25.htm#n6