News / Africa

    Could Rising Temperatures Mean Smaller Mammals?

    Teeth of miniature dog-sized horse that lived in Wyoming 56 million years ago.
    Teeth of miniature dog-sized horse that lived in Wyoming 56 million years ago.
    Joe DeCapua

    Scientists say in the ancient past, higher temperatures meant smaller mammals. They’re studying how a brief, but dramatic climate change event affected body size.

    It’s called the Paleocene-Eocene Thermal Maximum or PETM for short. It took place 56 million years ago and lasted about 175,000 years. That’s a long time in human terms, but a blink of an eye in the geological record.

    Jonathan Bloch said a lot happened back then.

    “We had known it was a really unique event for a while in the sense that it was a very rapid, large scale global warming event. And it marks one of the most important moments in mammalian evolution in the sense that we see the first occurrence of several modern orders of mammals, including the primates that are clearly traceable as the direct ancestors of the group that we’re a part of, as well as the ancestors of horses, the ancestors of cows and hippos and camels,” he said.

    Jonathan Bloch of the Florida Museum of Natural History
    Jonathan Bloch of the Florida Museum of Natural History

    Bloch is associate curator of vertebrate paleontology at the Florida Museum of Natural History at the University of Florida. He and colleagues from eight institutions were collecting fossils in the state of Wyoming’s Bighorn Basin.

    Tiny horses

    “For the past 9 years, we’ve been slowly, slowly collecting teeth, and sometimes more than teeth, fragmentary jaws, of the first horses to come in. And what we started to find was something pretty surprising to us. We had known that the horses that came in initially with that event 56 million years ago were very small, about the size of a small dog. But what we didn’t realize was that in fact when they came in they were a little bit larger than we had expected; and that through the climate event they became about 30 percent smaller and then became larger again,” he said.

    Then, Bloch said, fellow researcher Ross Secord, now at the University of Nebraska, took a closer look at what are called oxygen isotopes. These were found in the teeth of the horses. The relationship between oxygen and carbon in these isotopes can provide much information.

    “What he showed was that exactly coincident with this body size change that we had documented there were shifts in the oxygen isotope that showed it was getting warmer as the horses were getting smaller. And then as the horses became larger again it became cooler,” he said.

    They concluded that temperature change resulted in smaller horses.

    Climate itself is changing through this interval by as much as 10 degrees [Celsius] at high latitudes and perhaps as low as 5 degrees in lower latitudes. So that’s a large scale event and it starts to put us in the range of the kind of climate shift that is being predicted by climate models today say for the next 100 years.

    Looking to the past, not future

    But paleontologists, like Bloch, don’t try to predict future climate change. They look to the past to try to understand the present.

    “Because the Earth went through substantial climate change in the past – some of it very rapid and large scale – there’s a record in the rocks for exactly how animals and plants responded. And so we can go back as paleontologists and just reap the benefits of those experiments. We document that by collecting fossils and studying them. And then we can report them to the world with regards to how we should think about the reaction of plants and animals to the potential future climate change. With regards to how much we know about future climate change, that’s really a round for climate scientists and climate modelers,” he said.

    Now, although the focus was on tiny horses 56 million years ago, the question still arises as to whether rising temperatures will mean smaller people in the future? Bloch says that’s possible. But there are a lot of factors involved. Right now, humans are getting bigger and that’s generally due to better nutrition. Humans could also adapt to rising temperatures by spending more time in air conditioned spaces.

    There’s evidence today that temperatures and mammal size are linked.

    “What you’re referring to is an observation that’s been coined Bergmann’s rule. And essentially what this rule says is that mammals of smaller size live in warmer environments and mammals of larger size live in cooler environments. And this has been documented in many different species of mammals,” said Bloch.

    So maybe the lesson for future humans is to eat well and stay cool.

    In the meantime, Bloch and his colleagues will continue to collect fossils in the Bighorn Basin. He says their future discoveries may be of interest to climate scientists.

    Their latest findings can be found in the February 24th issue of Science magazine.

    You May Like

    Republicans Struggle With Reality of Trump Nomination

    Despite calls for unity by presumptive presidential nominee, analysts see inevitable fragmentation of party ahead of November election and beyond

    Spanish Warrants Point to Russian Govt. Links to Organized Crime

    Links to several Russians, some of them reputedly close Putin associates, backed by ‘very strong evidence,’ Spanish judge says

    Video US Worried Political Chaos in Iraq Will Hurt IS Fight

    Iraq needs stable, central government to push back against Islamic State, US says, but others warn that Baghdad may not have unified front any time soon

    This forum has been closed.
    Comments
         
    There are no comments in this forum. Be first and add one

    By the Numbers

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Press Freedom in Myanmar Fragile, Limitedi
    X
    Katie Arnold
    May 04, 2016 12:31 PM
    As Myanmar begins a new era with a democratically elected government, many issues of the past confront the new leadership. Among them is press freedom in a country where journalists have been routinely harassed or jailed.
    Video

    Video Press Freedom in Myanmar Fragile, Limited

    As Myanmar begins a new era with a democratically elected government, many issues of the past confront the new leadership. Among them is press freedom in a country where journalists have been routinely harassed or jailed.
    Video

    Video Taliban Threats Force Messi Fan to Leave Afghanistan

    A young Afghan boy, who recently received autographed shirts and a football from his soccer hero Lionel Messi, has fled his country due to safety concerns. He and his family are now taking refuge in neighboring Pakistan. VOA's Ayaz Gul reports from Islamabad.
    Video

    Video Major Rubbish Burning Experiment Captures Destructive Greenhouse Gases

    The world’s first test to capture environmentally harmful carbon dioxide gases from the fumes of burning rubbish took place recently in Oslo, Norway. The successful experiment at the city's main incinerator plant, showcased a method for capturing most of the carbon dioxide. VOA’s Deborah Block has more.
    Video

    Video EU Visa Block Threatens To Derail EU-Turkey Migrant Deal

    Turkish citizens could soon benefit from visa-free travel to Europe as part of the recent deal between the EU and Ankara to stem the flow of refugees. In return, Turkey has pledged to keep the migrants on Turkish soil and crack down on those who are smuggling them. Brussels is set to publish its latest progress report Wednesday — but as Henry Ridgwell reports from London, many EU lawmakers are threatening to veto the deal over human rights concerns.
    Video

    Video Tensions Rising Ahead of South China Sea Ruling

    As the Philippines awaits an international arbitration ruling on a challenge to China's claims to nearly all of the South China Sea, it is already becoming clear that regardless of which way the decision goes, the dispute is intensifying. VOA’s Bill Ide has more from Beijing.
    Video

    Video Painting Captures President Lincoln Assassination Aftermath

    A newly restored painting captures the moments following President Abraham Lincoln’s assassination in 1865. It was recently unveiled at Ford’s Theatre in Washington, where America’s 16th president was shot. It is the only known painting by an eyewitness that captures the horror of that fateful night. VOA’s Julie Taboh tells us more about the painting and what it took to restore it to its original condition.
    Video

    Video Elephant Summit Results in $5M in Pledges, Presidential Support

    Attended and supported by three African presidents, a three-day anti-poaching summit has concluded in Kenya, resulting in $5 million in pledges and a united message to the world that elephants are worth more alive than dead. The summit culminated at the Nairobi National Park with the largest ivory burn in history. VOA’s Jill Craig attended the summit and has this report about the outcomes.
    Video

    Video Displaced By War, Syrian Artist Finds Inspiration Abroad

    Saudi-born Syrian painter Mohammad Zaza is among the millions who fled their home for an uncertain future after Syria's civil war broke out. Since fleeing Syria, Zaza has lived in Lebanon, Egypt, Jordan and now Turkey where his latest exhibition, “Earth is Blue like an Orange,” opened in Istanbul. He spoke with VOA about how being displaced by the Syrian civil war has affected the country's artists.
    Video

    Video Ethiopia’s Drought Takes Toll on Children

    Ethiopia is dealing with its worst drought in decades, thanks to El Nino weather patterns. An estimated 10 million people urgently need food aid. Six million of them are children, whose development may be compromised without sufficient help, Marthe van der Wolf reports for VOA from the Metahara district.
    Video

    Video Little Havana - a Slice of Cuban Culture in Florida

    Hispanic culture permeates everything in Miami’s Little Havana area: elderly men playing dominoes as they discuss politics, cigar rollers deep at work, or Cuban exiles talking with presidential candidates at a Cuban coffee window. With the recent rapprochement between Cuba and United States, one can only expect stronger ties between South Florida and Cuba.
    Video

    Video California Republicans Weigh Presidential Choices Amid Protests

    Republican presidential candidates have been wooing local party leaders in California, a state that could be decisive in selecting the party's nominee for U.S. president. VOA's Mike O’Sullivan reports delegates to the California party convention have been evaluating choices, while front-runner Donald Trump drew hundreds of raucous protesters Friday.
    Video

    Video ‘The Lights of Africa’ - Through the Eyes of 54 Artists

    An exhibition bringing together the work of 54 African artists, one from each country, is touring the continent after debuting at COP21 in Paris. Called "Lumières d'Afrique," the show centers on access to electricity and, more figuratively, ideas that enlighten. Emilie Iob reports from Abidjan, the exhibition's first stop.

    Special Report

    Adrift The Invisible African Diaspora