Ways to control human population
The numbers of humans on Earth have increased enormously during the past several millennia, but especially during the past two centuries. By the end of the twentieth century, the global population of humans was 6.0 billion. That figure is twice the population of 1960, a mere 30 years earlier. Moreover, the human population is growing at about 1.5% annually, equivalent to an additional 89 million people per year. The United Nations Population Fund estimates that there will likely be about nine billion people alive in the year 2050.
In addition, the numbers of animals that live in a domestic mutualism with humans have also risen. These companion species must be supported by the biosphere along with their human patrons, and can be considered an important component of the environmental impact of the human enterprise. The large domestic animals include about 1.7 billion sheep and goats, 1.3 billion cows, and 0.3 billion horses, camels, and water buffalo. Humans are also accompanied by a huge population of smaller animals, including 10-11 billion chickens and other fowl.
The biological history of Homo sapiens extends more than one million years. For almost all of that history, a relatively small population was engaged in a subsistence lifestyle, involving the hunting of wild animals and the gathering of edible plants. The global population during those times was about a million people. However, the discoveries of crude tools, weapons, and hunting and gathering techniques allowed prehistoric humans to become increasingly more effective in exploiting their environment, which allowed increases in population to occur. About ten thousand years ago, people discovered primitive agriculture through the domestication of a few plant and animal species, and ways of cultivating them to achieve greater yields of food.
Further increases in Earth's carrying capacity for the human population were achieved through additional technological...