Longer Human Lives May Harm Our Wildlife

We humans, without doubt, have had the greatest influence on our environment, more than any other species on earth. There are more of us on the planet now than ever before, established in every corner of the globe. Our impact on biodiversity in the last 50 years is alarming: half of all seed plants, a third of all amphibians, and almost a quarter of all mammals are threatened with extinction, according to a report in 2005 – their status now is probably grimmer. A recent study found that countries with higher life expectancies actually had more invasive and endangered species and those with a higher GDP per capita had more invasive species.

To understand the complex ways we influence biodiversity (the variety of living species), researchers explored how unique ecological, economic and social factors correlate with the prevalence of endangered or invasive mammals and birds in 100 countries, comprising 87% of the world’s population.

The ecological variables included agricultural intensity, rainfall, water stress, wilderness protection, and total biodiversity; economic variables examined were GDP per capita, import-export ratio, tourism, undernourishment, and energy efficiency; and social variables covered life expectancy, adult literacy, pesticide regulation, political stability, and female participation in government.

Invasive species of plants and animals – usually introduced by humans either deliberately or inadvertently through food imports, for example – can disrupt ecosystems, devastate crops, spread disease, and drive native species to extinction by out-competing them. The resulting decline of native species can wreak havoc, upsetting predator-prey associations, overall biodiversity, and ultimately the resilience of ecosystems.

Sumatran Orangutans, found only on the Sumatran island and live exclusively on trees, are critically endagered.  Image: Wikipedia

Sumatran Orangutans, found only in the forests of the Sumatran island, are critically endangered – mainly due to their disappearing habitat and illegal hunting.
Image: Wikipedia

The researchers discovered that increased life expectancy was associated with more endangered and invasive birds and mammals. Countries with high life expectancies such as the United States, Australia, New Zealand, Indonesia, and the Philippines also had the highest percentage of birds and mammals that are endangered.

The authors postulate that as people live longer, they consume more resources – like food, water, and gas – and thus their carbon and ecological footprint is greater.

Slash and burn cultivation in Thailiand Image: FreeDigitialPhotos

Slash and burn cultivation in Thailiand
Image: FreeDigitialPhotos

African countries had the lowest percentages of invasive and endangered birds and mammals. The lack of invasive species was attributed to the regions’ relatively closed international trade policies compared with other countries.

New Zealand was an interesting and extreme case; it had the highest percentage of endangered and invasive species among all the countries – more than twice as high as most of the other countries. The researchers suggest that the reason is due to its fairly recent human colonization in the last 800 years, its geographical isolation, and its lack of indigenous land mammals.

Stoats were introduced into New Zealand in the 1880s to control rabbits, but they decimated the native bird populations.  Image: BozMo

Stoats were introduced into New Zealand in the 1880s to control rabbits, but they decimated the native bird populations.
Image: BozMo

They also found an increased GDP per capita is associated with more invasive birds and mammals, which is consistent with other studies. Countries with a higher GDP usually engage actively in international trade, expanding opportunities for the introduction of invasive species.

We usually associate higher incomes and high life expectancies as indicators of human development. But development comes with grave costs to our environment, as revealed by this study, which may in the long-term threaten us in unforeseen ways. Adopting lifestyle changes – such as saving gas, forests, and water – to minimize our carbon footprint can help offset the fact that we’re living longer.

While highly relevant, the study overlooked some important economic variables such as population density, diet composition, inequality, corruption index, and illegal wildlife trade that could have revealed additional insights.

A high population density of a country may limit the amount of land available to accommodate a population. As a result, overcrowding occurs and poor residents may be inadequately housed, forcing them to tear down more tracts of forest to build homes.

The diet composition of a population, particularly how often meat is consumed on average, may vary drastically between countries. The more frequently a population eats meat, the greater their carbon and ecological footprint, which in turn affects endangered and invasive species.

High levels of inequality or extreme gaps between the rich and poor in some countries highlight disproportionate distribution of resources, which may indirectly affect the environment.

With rampant corruption in many developing countries, a corruption index may elucidate novel impacts on the environment. For example, unscrupulous officials who follow their own financial interests and agenda – stealing funds meant for ecological or wildlife restoration projects – may harm endangered species by inadequate implementation and enforcement of wildlife protection policies.

Finally, unprecedented levels of illegal wildlife trade, fueled by demand for exotic species, is causing the decline of countless species and inadvertently introducing harmful species. According to the WWF, this is the second largest threat to wildlife species – second to habitat destruction.

Nevertheless, this study underscores the urgent need for sustainable development in all countries. In our quest to prolong our lives, we are truncating the lives of other species, wiping some out completely.

Conservation strategies worldwide must educate the public about the consequences of their constant environmental assaults and the sustainable practices they should adopt – before it is too late. But the authors stress that these practices can “only be successful if local communities are given the incentives, tools”, and realize “that they are living on environmental capital rather than on interest.”


Lotz, A., and C. R. Allen. 2013. Social-ecological predictors of global invasions and extinctionsEcology and Society 18(3): 15.

Additional Interesting Reads

An eye-opening 2012 report on Sumatran rainforests by the World Wildlife Fund: Don’t Flush Tiger Forests

Overview of Illegal Wildlife Trade by the WWF


One thought on “Longer Human Lives May Harm Our Wildlife

  1. Pingback: The Art of Sustainable Living | Life Science Exploration

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