In the chapter on population, we discussed how and why population growth exploded in the 20th century. Recall that as nations evolve from Stage 1 to Stage 2, death rates plummet, but birth rates are maintained at their current levels, causing an explosion in population. Europe and America were the first nations to enter Stage 2, but today no nation is in Stage 1. Most nations are still in Stage 2, and the result of this is that the human population is now over 7.5 billion. Our numbers are expected to peak at 9 billion by 2100.
The 20th century was also the deadliest century, in terms of war, in human history. This century experienced two world wars, multiple civil wars, genocides in Rwanda (Tutsis and moderate Hutus), Sudan, Yugoslavia, and the Holocaust that decimated the Jewish population in Europe during WWII. In addition to WWI and WWII, this century experienced the Korean War, the Vietnam War, the Cold War, and the first Gulf War. Additionally, this century saw regional and civil conflicts such as those experienced in the Congo (6 million people died), as well as an upsurge in child soldiers and modern slavery.