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

Katrina Brought Enduring Changes to New Orleans

The city’s recovery is the result of the people and culture the city is famous for, as well as newcomers and start-up industries More

China to Open Stock Markets to Pension Funds

In unprecedented move, government to soon allow local pension funds to invest up to $94 billion in domestic shares More

Magical Photo Slides Show Native Americans in Late 1800s

Walter McClintock spent 20 years photographing the Blackfoot Indians and their vanishing culture at the dawn of the modern age 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.
Colombians Flee Venezuela as Border Crisis Escalatesi
X
August 27, 2015 2:08 AM
Hundreds of Colombians have fled Venezuela since last week, amid an escalating border crisis between the two countries. Last week, Venezuelan President Nicolas Maduro ordered the closure of a key border crossing after smugglers injured three Venezuelan soldiers and a civilian. The president also ordered the deportation of Colombians who are in Venezuela illegally. Zlatica Hoke reports.
Video

Video Colombians Flee Venezuela as Border Crisis Escalates

Hundreds of Colombians have fled Venezuela since last week, amid an escalating border crisis between the two countries. Last week, Venezuelan President Nicolas Maduro ordered the closure of a key border crossing after smugglers injured three Venezuelan soldiers and a civilian. The president also ordered the deportation of Colombians who are in Venezuela illegally. Zlatica Hoke reports.
Video

Video Is China's Economic Data Accurate?

Some investors say China's wild stock market gyrations have been made worse by worries about the reliability of that nation's economic data. And some critics say the reports can mislead investors by painting an unrealistically-strong picture of the economy. A key China scholar says Beijing is not fudging ((manipulating)) the numbers, but that the economy is evolving quickly from smoke-stack industries to services, and the ways of tracking new economic activity are falling behind the change. V
Video

Video Next to Iran, Climate at Forefront of Obama Agenda

President Barack Obama this week announced new initiatives aimed at making it easier for Americans to access renewable energy sources such as solar and wind. Obama is not slowing down when it comes to pushing through climate change measures, an issue he says is the greatest threat to the country’s national security. VOA correspondent Aru Pande has more from the White House.
Video

Video Shipping Containers Provide Experimental Housing

Housing prices around the San Francisco Bay area are out of reach for many people, so some young entrepreneurs, artists and tech industry workers are creating their own houses using converted shipping containers. But as VOA's Mike O’Sullivan reports from Oakland, the effort requires ingenuity and dealing with restrictive local laws.
Video

Video Arctic Draws International Competition for Oil

A new geopolitical “Great Game” is underway in earth’s northernmost region, the Arctic, where Russia has claimed a large area for resource development and President Barack Obama recently approved Shell Oil Company’s test-drilling project in an area under U.S. control. Greg Flakus reports.
Video

Video Philippine Maritime Police: Chinese Fishermen a Threat to Country’s Security

China and the Philippines both claim maritime rights in the South China Sea.  That includes the right to fish in those waters. Jason Strother reports on how the Philippines is catching Chinese nationals it says are illegal poachers. He has the story from Palawan province.
Video

Video Technique May Eliminate Drill-and-Fill Dental Care

Many people dread visiting dentists because they're afraid of drills. Now, however, a technology developed by a British firm promises to eliminate the need for mechanical cleaning of dental cavities by speeding a natural process of tooth repair. VOA’s George Putic reports.
Video

Video China's Spratly Island Building Said to Light Up the Night 'Like A City'

Southeast Asian countries claim China has illegally seized territory in the Spratly islands. It is especially a concern for a Philippine mayor who says Beijing is occupying parts of his municipality. Jason Strother reports from the capital of Palawan province, Puerto Princesa.
Video

Video Ages-old Ice Reveals Secrets of Climate Change

Ice caps don't just exist at the world's poles. There are also tropical ice caps, and the largest sits atop the Peruvian Andes - but it is melting, quickly, and may be gone within the next 20 years. George Putic reports scientists are now rushing to take samples to get at the valuable information about climate change locked in the ice.
Video

Video French Experiment in Integrating Roma Under Threat

Plans to destroy France’s oldest slum have sparked an outcry on the part of its Roma residents. As Lisa Bryant reports from the Paris suburb of La Courneuve, rights groups argue the community is a fledgling experiment on integrating Roma who are often outcasts in many parts of Europe.
Video

Video Kenyans Turn to Agriculture for Business

Each year Kenyan universities continue to churn out graduates for the job market despite the already existing high rate of unemployment among youth in the country. Some of these young men and women have realized that agriculture can be as rewarding as any other business or job, and they are resorting to agribusiness in large numbers as a way of tackling unemployment. Rael Ombuor reports for VOA.
Video

Video First Women Graduate Elite Army Ranger School

Two women are making history for the U.S. Army by proving they are among the toughest of the tough. VOA's Carla Babb reports from Fort Benning, Georgia as 94 men and those two women rise as graduates of the difficult Ranger school.

VOA Blogs