By Douglas Main
Until about 2,000 years ago, no human had set foot on Madagascar. This wonderland of wildlife east of Africa is home to all of the world's lemurs, a diverse group of primates, most of which have fox-like faces and large eyes. Lemurs descend from animals that arrived on the isolated island between 50 million and 60 million years ago.
Since humans arrived, about 15 to 20 of these lemur species have gone extinct, likely due to habitat loss and hunting, including species whose males grew nearly as large as gorillas. But these die-offs happened over the course of hundreds and thousands of years. Humans are impacting the island at a much faster pace now. As Malagasy populations rise, humans threaten the remaining species of lemurs and thousands of other species with extinction at an accelerating rate, said University of Illinois primatologist Paul Garber.
Currently, 93 lemur species are endangered, critically endangered or threatened, mostly due to the clearing of the island's forests, according to the International Union for Conservation of Nature (IUCN), a global environmental organization. That's 91 percent of all lemur species for which data is available.
Deforestation has sped up in the second half of the 20th century, and in the last 60 years, half of the island's remaining forests have been cleared, according to a 2007 study in the journal Biology Letters. During that time, the country's population has quadrupled, according to the World Bank, a global financial institution that offers loans to developing countries. But it's not just the animals' homes that are vanishing — sometimes, the animals themselves are taken. Since the breakdown of civil order following a 2009 coup in the country, species such as collared lemurs have been taken from forests to be sold in the illegal pet trade, and they have been killed by hunters to be eaten as bush meat, according to various news reports.
The plight of Madagascar's lemurs is just one example of how a rising population of humans is contributing to the sixth-largest mass extinction in the history of the planet, most biologists say. According to the IUCN, 20,000 species of animals and plants are considered at high risk for extinction, meaning there is a good chance they could die out if steps aren't taken to ensure their survival. If species continue to die out at current rates, more than 75 percent of all species currently on Earth could go extinct within a few centuries, according to a 2011 study in the journal Nature.
The extinction rate is estimated to be 100 to 1,000 times the natural "background" rate as a result of human activities, said Stacy Small-Lorenz, a conservation scientist at the Environmental Defense Fund, an environmental group whose mission is to protect the natural environment. More....