Human Population

The human species, Homo sapiens, is by far the most abundant large animal on Earth. Our world population is growing at about 1.5% annually, that is, at about 80 million people per year. If the percentage of annual growth remains constant, the number of people added yearly increases: 1.5% of 100 is 1.5, but 1.5% of 200 is 3. Thus, 80 million new people per year is an approximate figure valid only for a short space of years. Also, global birth rates vary from year to year. If the current rate of growth is maintained, the size of the human population will double in less than 50 years, at which time there will be more than 12 billion people on Earth.

No other large animal is known to have ever achieved such an enormous abundance. Prior to overhunting during the nineteenth century, the American bison (Bison bison) numbered 60–80 million animals and may have been the world's most populous wild large animal. The most abundant large animals in the wild now are the white-tailed deer (Odocoileus virginianus) of the Americas, with 40–60 million individuals, and the crabeater seal (Lobodon carcinophagus) of Antarctica, with 15–30 million. These species have populations less than 1% of that of human beings at this time.

Large animals domesticated by human beings have also become enormously abundant, and these companion species must be supported by the biosphere in concert with their human patrons. Therefore, they must be considered an important component of the environmental impact of the human population. These animals include about 1.7 billion sheep and goats, 1.3 billion cows, and 0.3 billion horses, camels, and water buffalo. Human beings are also accompanied by enormous populations of smaller domesticated animals, including 10–11 billion chickens and other fowl.