Jared Diamond, Collapse: How Societies Choose to Fail or Succeed (2005).
CHAPTER 10: Malthus in Africa: Rwanda's Genocide
A dilemma ■ Events in Rwanda ■ More than ethnic hatred ■ Buildup in Kanama ■
Explosion in Kanama ■ Why it happened
When my twin sons were 10 years old and again when they were 15, my wife and I
took them on family vacations to East Africa. Like many other tourists, the four of us were
overwhelmed by our firsthand experience of Africa's famous large animals, landscapes, and
people. No matter how often we had already seen wildebeest moving across the TV screen of
National Geographic specials viewed in the comfort of our living rooms, we were unprepared
for the ...view middle of the document...
All of those children add up to rates of human population growth in East Africa that are
among the highest in the world: recently, 4.1% per year in Kenya, resulting in the population
doubling every 17 years. That population explosion has arisen despite Africa's being the
continent inhabited by  humans much longer than any other, so that one might naively
have expected Africa's population to have leveled off long ago. In fact, it has been exploding
recently for many reasons: the adoption of crops native to the New World (especially corn,
beans, sweet potatoes, and manioc, alias cassava), broadening the agricultural base and
increasing food production beyond that previously possible with native African crops alone;
improved hygiene, preventive medicine, vaccinations of mothers and children, antibiotics,
and some control of malaria and other endemic African diseases; and national unification and
the fixing of national boundaries, thereby opening to settlement some areas that were
formerly no-man's lands fought over by adjacent smaller polities.
Population problems such as those of East Africa are often referred to as "Malthusian,"
because in 1798 the English economist and demographer Thomas Malthus published a
famous book in which he argued that human population growth would tend to outrun the
growth of food production. That's because (Malthus reasoned) population growth proceeds
exponentially, while food production increases only arithmetically. For instance, if a
population's doubling time is 35 years, then a population of 100 people in the year 2000, if it
continues to grow with that same doubling time, will have doubled in the year 2035 to 200
people, who will in turn double to 400 people in 2070, who will double to 800 people in the
year 2105, and so on. But improvements in food production add rather than multiply: this
breakthrough increases wheat yields by 25%, that breakthrough increases yields by an
additional 20%, etc. That is, there is a basic difference between how population grows and
how food production grows. When population grows, the extra people added to the
population also themselves reproduce -- as in compound interest, where the interest itself
draws interest. That allows exponential growth. In contrast, an increase in food yield does not
then further increase yields, but instead leads only to arithmetic growth in food production.
Hence a population will tend to expand to consume all available food and never leave a
surplus, unless population growth itself is halted by famine, war, or disease, or else by people
making preventive choices (e.g., contraception or postponing marriage). The notion, still
widespread today, that we can promote human happiness merely by increasing food
production, without a simultaneous reining-in of population growth, is doomed to end in
frustration -- or so said Malthus.
The validity of his pessimistic argument has been much debated. Indeed, there are