Answer to Question 1
To say that the population is too large or too small implies there is an optimal size, but no exact figure could accurately be considered the ideal population for the world. Many variables and values would enter into specifying an optimal world population size, including preservation of a certain standard or quality of life, rate of consumption of nonrenewable raw materials, future technological breakthroughs in finding new energy and food sources, maintenance of safe levels of clean air and water, and public acceptance of the government's role (perhaps compulsory) in population control. The industrialized nations, with their high-consumption and high-waste economies, are using up more of the earth's raw materials and generating more pollution than are developing countries. Because of consumption rates, adding 1 million people to industrialized countries is comparable to adding 30 million people to developing countries.
With regard to the question of whether the earth is already overpopulated, Paul Ehrlich and Anne Ehrlich note: The key to understanding overpopulation is not population density but the numbers of people in an area relative to its resources and the capacity of the environment to sustain human activities; that is, to the area's carrying capacity. When is an area overpopulated? When its population can't be maintained without rapidly depleting nonrenewable resources (or converting renewable resources into nonrenewable ones) and without degrading the capacity of the environment to support the population. In short, if the long-term carrying capacity of an area is clearly being degraded by its current human occupants, that area is overpopulated. By this standard, the entire planet and virtually every nation is already vastly overpopulated.
Answer to Question 2
d
Difficulties in applying the morphological species concept
Stellar Size and Spectra
Projections of the Racial-Ethnic Makeup of the U.S. Population
The developing and emerging nations have high rates of population growth
Relationship Between Income per Capita and Population Growth
Illustration of the concept of overlapping genes