News / Science & Technology

    Humans Driving Massive Animal Extinction

    Long-term experiments on fenced-off plots of land in Kenya show the cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Credit: Hillary Young)
    Long-term experiments on fenced-off plots of land in Kenya show the cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Credit: Hillary Young)
    Rosanne Skirble

    Earth is in the midst of its sixth mass extinction of animal species  -- the first to be caused by humans -- in the past half-billion years, setting off a downward spiral in the environment and human health, which will accelerate unless action is taken, according to a new report in Science.

    Co-author Hillary Young studies what happens when the big animals disappear. In her field work in Central Kenya, the University of California Santa Barbara researcher documents changes in four-hectare parcels of land, fenced to keep out giraffes and zebras and elephants.  

    “We can measure things like the abundance of vegetation, the abundance of rodents, and the prevalence of disease in the wildlife species that are left behind,” she said.

    Rapid decline

    Rather quickly the fenced parcels fill with grasses and shrubs, providing cover for rats which overwhelm the area and are vectors for human disease.  

    Humans Driving Massive Animal Extinction
    Humans Driving Massive Animal Extinctioni
    || 0:00:00
    ...    
     
    X

    Young and her colleagues have coined a new term for this pattern of animal species loss. They call it defaunation.  

    “We have lost more than 25 percent of all the vertebrates in the world - this is the number of individual animals in the world - and probably more than 45 percent of the invertebrate animals in the world," she observed. "On an average year, we’re probably losing 11,000 to 58,000 animal species. That’s just shocking to think about.”    

    Beetles, bugs and butterflys disappearing too

    This loss is all the more surprising, Young says, because similar patterns are playing out across species worldwide.  

    • Large mammals such as the tapir are the first to disappear in human-modified ecosystems. (Mauro Galetti)
    • White-lipped peccaries used to be the dominant terrestrial mammals in South American rainforests. (Mauro Galetti)
    • Muriquis and other large primates are vanishing from tropical ecosystems. (Pedro Jordano)
    • Scientists are studying the effects of defaunation in tropical forests. (Mauro Galetti)
    • Aldabra giant tortoises, introduced to Round Island, Mauritius, as ecological replacements for the extinct Mauritian giant tortoises, eat the fast-growing invasive flora. (Christine Griffiths)
    • Aldabra giant tortoises being re-located to the offshore Mauritian island, Round Island, over 150 years after the native giant tortoises went extinct. (Christine Griffiths)
    • Coal burning power plants are the biggest source of carbon pollution, which is responsible for climate change, which is also driving animal decline.
    • A warmer climate brings changes to the flora and fauna as in this major tributary of the Amazon river in Brazil, which pushed water levels to new lows. 
    • Long-term experiments in central Kenya remove large wildlife, such as zebra and elephants, with high voltage electric fencing. The studies demonstrate strong cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Duncan Kimuyu)
    • Defaunation is leading to declines in selective large mammals. Small mammals, such as mice (shown here, the broad headed mouse, Zelotomys hildagardae) benefit, and often cause nuisances to humans by vectoring diseases or destroying crops. (Lauren Helge)
    • The Maasia people in Kenya are an example of a community whose livelihood will likely be strongly impacted by continuing defaunation. (Jack Silange)

    “We tend to think of extinction and species decline in the terms of giant pandas or polar bears, but what we find is that these small invertebrates - the beetles, the worms, the moths and the ladybugs - those animals are declining at rates that were equivalent if not greater than the large species,” she said.  

    These are signs, Young says, that the sixth mass extinction is under way. The study affirms that humans are speeding it up by destroying wild lands and over-exploiting animals and resources. This, in turn, has triggered invasions of exotic species and climate change on a grand scale.

    Animals protect vital human services

    Young says conservation is not an esoteric luxury to keep wildlife around.

    “Basic ecosystem functions like soil protection or water purification or carbon cycling to keep the soils rich and the atmosphere clean - all of those are services provided by animals, often these invertebrates that we don’t think about so much, but also the larger vertebrates," she said. "And what we find is that when we lose these animals, we see massive changes in these ecosystems, functions in the systems that are impacted.”

    As species die off, Young warns that defaunation can permanently upset the trajectory of life on Earth.  She says that loss, if left unchecked, will become a driver of global change rather than a consequence of it.   

    “It is going to exacerbate climate change [and] water stress. It is going to increase human poverty and social conflict. These are themselves going to lead to more wildlife declines, and it’s going to create a downward spiral and we’re going to lose the opportunity to halt this spiral,” she said.

    Young says slowing this planetary nightmare will require political will. She says immediately addressing habitat loss and over-exploitation of animals and resources would help in the short term, but in the long run, global action to curb climate change is imperative.

    You May Like

    US Leaders Who Served in Vietnam War Look Back and Ahead

    In New York Times opinion piece, Secretary of State John Kerry, Senator John McCain and former Senator Bob Kerrey say as US strengthens relations with Vietnam, it is important to remember lessons learned from war

    Who Are US Allies in Fight Against Islamic State?

    There is little but opportunism keeping coalition together analysts warn — SDFs Arab militias are not united even among themselves, frequently squabble and don’t share Kurds' vision for post-Assad Syria

    Learning Foreign Language Helps US Soldiers Bridge Culture Gap

    Effective interaction with local populations part of everyday curriculum at Monterey, California, Defense Language Institute

    This forum has been closed.
    Comment Sorting
    Comments
         
    by: Jeffrey Tischler from: Monterey, California
    July 26, 2014 11:17 AM
    Nary a word on human overpopulation being a root cause of the disaster. There is no fix without long term plans to lower human populations globally. I prefer natural attrition to famine and war.

    by: Eric Mills from: Oakland, CA
    July 25, 2014 6:32 PM
    Homo sapiens - "wise" no, "clever" surely.

    Recommended reading:

    THE SIXTH EXTINCTION, by Elizabeth Kolbert (Holt & Co., NYC, 2012), a NY TIMES bestseller;

    SPILLOVER: Animal Infections and the Next Human Pandemic, by David Quammen (Norton & co. NYC, 2012);

    DEATH AT SEAWORLD, by David Kirby (St. Martin's Press, NYC, 2012).

    As the bumper strip says, "We're not the only species on the planet, we just act like it." Sadly, methinks that global warming and human hubris will soon make all this moot.

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Vietnamese-American Youth Optimistic About Obama's Visit to Vietnami
    X
    Elizabeth Lee
    May 22, 2016 6:04 AM
    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video Vietnamese-American Youth Optimistic About Obama's Visit to Vietnam

    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video First-generation, Afghan-American Student Sets Sights on Basketball Glory

    Their parents are immigrants to the United States. They are kids who live between two worlds -- their parents' homeland and the U.S. For many of them, they feel most "American" at school. It can be tricky balancing both worlds. In this report, produced by Beth Mendelson, Arash Arabasadi tells us about one Afghan-American student who seems to be coping -- one shot at a time.
    Video

    Video Newest US Citizens, Writing the Next Great Chapter

    While universities across the United States honor their newest graduates this Friday, many immigrants in downtown Manhattan are celebrating, too. One hundred of them, representing 31 countries across four continents, graduated as U.S. citizens, joining the ranks of 680,000 others every year in New York and cities around the country.
    Video

    Video Vietnam Sees Strong Economic Growth Despite Incomplete Reforms

    Vietnam has transformed its communist economy to become one of the world's fastest-growing nations. While the reforms are incomplete, multinational corporations see a profitable future in Vietnam and have made major investments -- as VOA's Jim Randle reports.
    Video

    Video Qatar Denies World Cup Corruption

    The head of Qatar’s organizing committee for the 2022 World Cup insists his country's bid to host the soccer tournament was completely clean, despite the corruption scandals that have rocked the sport’s governing body, FIFA. Hassan Al-Thawadi also said new laws would offer protection to migrants working on World Cup construction projects. VOA's Henry Ridgwell reports.
    Video

    Video Infrastructure Funding Puts Cambodia on Front Line of International Politics

    When leaders of the world’s seven most developed economies meet in Japan next week, demands for infrastructure investment world wide will be high on the agenda. Japanese Prime Minister Shinzo Abe’s push for “quality infrastructure investment” throughout Asia has been widely viewed as a counter to the rise of Chinese investment flooding into region.
    Video

    Video Democrats Fear Party Unity a Casualty in Clinton-Sanders Battle

    Democratic presidential front-runner Hillary Clinton claimed a narrow victory in Tuesday's Kentucky primary even as rival Bernie Sanders won in Oregon. Tensions between the two campaigns are rising, prompting fears that the party will have a difficult time unifying to face the presumptive Republican nominee, Donald Trump. VOA national correspondent Jim Malone has more from Washington.
    Video

    Video Portrait of a Transgender Marriage: Husband and Wife Navigate New Roles

    As controversy continues in North Carolina over the use of public bathrooms by transgender individuals, personal struggles with gender identity that were once secret are now coming to light. VOA’s Tina Trinh explored the ramifications for one couple as part of trans.formation, a series of stories on transgender issues.
    Video

    Video Amerikan Hero Flips Stereotype of Middle Eastern Character

    An Iranian American comedian is hoping to connect with American audiences through a film that inverts some of Hollywood's stereotypes about Middle Eastern characters. Sama Dizayee reports.
    Video

    Video Budding Young Inventors Tackle City's Problems with 3-D Printing

    Every city has problems, and local officials and politicians are often frustrated by their inability to solve them. But surprising solutions can come from unexpected places. Students in Baltimore. Maryland, took up the challenge to solve problems they identified in their city, and came up with projects and products to make a difference. VOA's June Soh has more on a digital fabrication competition primarily focused on 3-D design and printing. Carol Pearson narrates.

    Special Report

    Adrift The Invisible African Diaspora