text: Myers himself "offered no basis for his prediction other than to call it a `reasonable working figure' Wilson cites as the basis of his prediction a mathematical equation known as the species-area curve that relates the size of an island to the number of species found on it. An island 10 square miles in area, for example, is typically found to have half as many species as a similar island of 100 square miles. Wilson argues that tropical forests obey exactly the same rule as their size is reduced. By plugging into the formula the rate at which tropical forests are being cut down throughout the world Wilson puts it at 2 percent per year he obtains the figure of 50,000 species lost each year. (U.S. News, p.82)