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

Kurdish Party Pushes Political Gamble to Run in Turkey Poll

HDP announces it will run as political party instead of fielding independent candidates in June election, but faces tough 10 percent threshold More

Twitter Targets Islamic State

New research shows suspending Twitter accounts of Islamic State, its supporters has been effective; group, its backers are facing 'significant pressure,' says terrorism expert More

Video Former Sudan 'Lost Boy' Becomes Chess Master in NYC

Majur Juac made the leap from being a refugee in Africa to a master chess champion in US, where he shares his expertise with students More

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.
NASA Monitors Earth’s Vital Signs From Spacei
X
Rosanne Skirble
January 27, 2015 5:05 PM
The U.S. space agency, NASA, is wrapping up its busiest 12-month period in more than a decade, with three missions launched in 2014 and two this month, one in early January and the fifth scheduled for January 29. As VOA’s Rosanne Skirble reports, the instruments being lifted into orbit are focused on Earth’s vital life support systems and how they are responding to a warmer planet.
Video

Video NASA Monitors Earth’s Vital Signs From Space

The U.S. space agency, NASA, is wrapping up its busiest 12-month period in more than a decade, with three missions launched in 2014 and two this month, one in early January and the fifth scheduled for January 29. As VOA’s Rosanne Skirble reports, the instruments being lifted into orbit are focused on Earth’s vital life support systems and how they are responding to a warmer planet.
Video

Video Saved By a Mistake - an Auschwitz Survivor's Story

Dagmar Lieblova was 14 when she arrived at Auschwitz in December 1943, along with her entire Czech Jewish family. All of them were to die there, but she was able to leave after several months due to a bureaucratic mix-up which saved her life. Now 85, with three children and six grandchildren, she says she has a feeling of victory. This report by Ahmad Wadiei and Farin Assemi, of RFE/RL's Radio Farda is narrated by RFE’s Raymond Furlong.
Video

Video Weekly Protests in Korea Keep Japanese WWII Atrocities Alive

Every week in Seoul protesters gather in front of the Japanese Embassy to demand an apology and reparations from Tokyo for the thousands of South Korean women who were forced into prostitution during World War II. Although this year marks the 70th anniversary of the end of the war, these protestors have helped keep the issue of comfort women alive and made it difficult for Japan to move beyond its past wartime atrocities. VOA's Brian Padden reports from Seoul.
Video

Video Exercise: New Prescription for Parkinsons Disease

Exercise could be the new prescription for Parkinson's Disease, a progressive disorder of the nervous system that affects movement. More than six million people worldwide suffer from Parkinsons and they're traditionally treated with medication and surgery. Shelley Schlender has more.
Video

Video Brussels Shaken as New Greek Leader Challenges Europe’s Austerity Drive

Greece’s youngest-ever prime minister, 40-year-old Alexis Tsipras, was sworn in Monday after his victorious far-left Syriza party entered a coalition with far right rivals. Tsipras says he will restore dignity to Greece by ending spending cuts. So begins a new chapter for the country at the epicenter of Europe’s economic crisis - a change that has sent tremors across the continent, as Henry Ridgwell reports from London.
Video

Video Obama Urges Closer Economic Ties During Historic India Visit

U.S. President Barack Obama says the United States and India must do better to capitalize on untapped potential in their economic relationship - by removing some of the roadblocks to greater trade and investment. As VOA correspondent Aru Pande reports from New Delhi, Obama spoke after participating in India’s Republic Day celebration.
Video

Video White House Grapples With Yemen Counterterrorism Strategy

Reports say the U.S. has carried out a drone strike on suspected militants in Yemen, the first after President Barack Obama offered reassurances the U.S. is continuing its counterterrorism operations in the country. The future of those operations has been in question following the collapse last week of Yemen’s government. VOA White House correspondent Luis Ramirez reports.
Video

Video Worldwide Photo Workshops Empower Youth

Last September, 20 young adults from South Sudan took part in a National Geographic Photo Camp. They are among hundreds of students from around the world who have learned how to use a camera to tell the stories of the people in their communities through the powerful medium of photography. Three camp participants talked about their experiences recently on a visit to Washington. VOA’s Julie Taboh reports.
Video

Video US, Japan Offer Lessons as Eurozone Launches Huge Stimulus

The Euro currency has fallen sharply after the European Central Bank announced a bigger-than-expected $67 billion-a-month quantitative easing program Thursday - commonly seen as a form of printing new money. Henry Ridgwell reports for VOA from London on whether the move might rescue the eurozone economy -- and what lessons have been learned from similar programs around the world.
Video

Video Oil Price Drop Troubles Texas Producers

As oil prices have fallen over the past several months, drilling operations have slowed in some parts of the United States - including Texas, the state that surpasses all others in energy production. The Lone Star State’s energy output has been boosted in recent years by development of resources trapped deep below ground in the Eagle Ford shale deposit, which stretches across south central Texas. As VOA’s Greg Flakus reports from Karnes City, Texas, the drop in oil prices has created concerns,
Video

Video Nigerian Elections Pose Concern of Potential Conflict in 'Middle Belt'

Nigeria’s north-central state of Kaduna has long been the site of fighting between Muslims and Christians as well as between people of different ethnic groups. As the February elections approach, community and religious leaders are making plans they hope will keep the streets calm after results are announced. Chris Stein reports from the state capital, Kaduna.
Video

Video As Viewership Drops, Obama Puts His Message on YouTube

Ratings reports show President Obama’s State of the Union address this week drew the lowest number of viewers for this annual speech in 15 years. White House officials anticipated this, and the president has decided to take a non-traditional approach to getting his message out. VOA White House correspondent Luis Ramirez reports.

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More

All About America

AppleAndroid