The study examined a combination of 15 social and ecological variables -- from tourism and per capita gross domestic product to water stress and political stability.
Then researchers analyzed their correlations with invasive and endangered birds and mammals, which are two indicators of what conservationist Aldo Leopold termed "land sickness."
Human life expectancy, which is rarely included among indexes that examine human impacts on the environment, surfaced as the key predictor of global invasions and extinctions.
The study analyzed data from 100 countries, which included roughly 87 percent of the world's population, 43 percent of global GDP per capita, and covered 74 percent of the Earth's total land area. Additional factors considered were agricultural intensity, rainfall, pesticide regulation, energy efficiency, wilderness protection, latitude, export-import ratio, undernourishment, adult literacy, female participation in government, and total population.
The study has been published in the journal Ecology and Society.
--ANI (Posted on 10-10-2013)