Living longer may be hurting some of Earth’s most vulnerable creatures.
According to a new study by the University of California, Davis, as human life expectancy increases so does the percentage of invasive and endangered birds and mammals. The findings, published in Ecology and Society, examined 15 social and ecological factors including tourism, GDP, water scarcity and political stability and correlated them with numbers drawn from invasive and endangered species.
“It’s not a random pattern,” lead author Aaron Lotz, a postdoctoral scholar in the Department of Wildlife, Fish and Conservation Biology, said in a statement. “Out of all this data, that one factor — human life expectancy — was the determining factor for endangered and invasive birds and mammals.”
Using data taken from 100 countries that represent 87 percent of the world’s population, 43 percent of global GDP per capita, and encompasses 74 percent of the Earth’s total land area, scientists found that as GDP per capita, total biodiversity and total land area increases in a given country so do the number of endangered species.
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A stark contrast of this can be seen in Africa whose countries have the lowest percentage of invasive and endangered animals. This may be due to the fact that the countries have less international trade, limiting the possibility of coming into contact with foreign invasive species.
New Zealand was considered an “extreme outlier” in the study. The island nation had the highest percentage of endangered birds, invasive birds and invasive mammals, and also had the highest percentage of all endangered and invasive species combined. Since human colonization in the past 700 to 800 years, the country has experienced a mass influx of nonindigenous species resulting in “catastrophic biodiversity loss.”
While past studies have focused on the relationship between humans and environmental degradation, this is one of the first to use life expectancy as a predictor of global invasions and extinctions in the animal world.
“Increased life expectancy means that people live longer and affect the planet longer; each year is another year of carbon footprint, ecological footprint, use of natural resources, etc. The magnitude of this impact is increased as more people live longer,” the authors wrote in the study.