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

Jihadist Assassin says Goal of Tunisia Murders Was Chaos

Abu Muqatil at-Tunusi’s remarks in a propaganda interview also cast light on attack on Bardo Museum More

Russia Denies License to Tatar-Language TV Station in Crimea

OSCE official says denial shows 'politically selective censorship of free and independent voices in Crimea is continuing' More

Kenyan Startups Tackle Expensive Remittances Through Bitcoin

Some think services could give Western Union a run for its money, though others say it’s still got a long way to go More

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

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
For Obama, It's More Business Than Friendships With World Leadersi
X
Aru Pande
April 01, 2015 9:09 PM
The rift between President Barack Obama and Israeli Prime Minister Benjamin Netanyahu has put a spotlight on the importance of the American leader’s personal relationships with other world leaders and what role such friendships play in foreign policy. VOA's Aru Pande reports.
Video

Video For Obama, It's More Business Than Friendships With World Leaders

The rift between President Barack Obama and Israeli Prime Minister Benjamin Netanyahu has put a spotlight on the importance of the American leader’s personal relationships with other world leaders and what role such friendships play in foreign policy. VOA's Aru Pande reports.
Video

Video Buhari: Nigeria Has ‘Embraced Democracy’

Nigeria woke up to a new president-elect Wednesday, Muhammadu Buhari. But people say democracy is the real winner as the country embarks on its first peaceful handover of power since the end of military rule in 1999. VOA’s Anne Look reports from Abuja.
Video

Video Tiny Camera Sees Inside Blood Vessels

Ahead of any surgical procedure, doctors try to learn as much as possible about the state of the organs they plan to operate on. A new camera developed in the Netherlands can now make that easier - giving surgeons an incredibly detailed look inside blood vessels, all the way to the patient’s heart. VOA’s George Putic has more.
Video

Video Latin American Groups Seek Fans at Texas Music Festival

Latin American music groups played all over Austin, Texas, during the recent South by Southwest festival, and some made fans out of locals as well as people from around the world who had come to hear music. Such exposure can boost such groups' image back home. VOA’s Greg Flakus reports.
Video

Video Stockton Community, Police, Work to Improve Relations

Relations are tense between minority communities and police departments around the United States following police shootings that have generated widely-publicized protests. VOA's Mike O’Sullivan reports from Stockton, California, where police and community groups are working toward solutions, with backing from Washington.
Video

Video Indiana Controversy Highlights Divergent Meanings of Religious Freedom

Indiana’s state government has triggered a nationwide controversy by approving a law that critics say is aimed at allowing discrimination against gays and lesbians. The controversy stems from divergent notions of religious freedom in America. VOA's Jerome Socolovsky reports.
Video

Video Report: State of Black America a 'Tale of Two Nations'

The National Urban League has described this year's "State of Black America" report as a "tale of two nations." The group's annual report, released earlier this month (March), found that under an equality index African Americans had only 72% parity compared to whites in areas such as education, economics, health, social justice and civic engagement. It’s a gap that educators and students at Brooklyn’s Medgar Evers College are looking to close. VOA's Daniela Schrier reports from the school.
Video

Video Film Tells Story of Musicians in Mali Threatened by Jihadists

At this year's annual South by Southwest film and music festival in Austin, Texas, some musicians from Mali were on hand to promote a film about how their lives were upturned by jihadists who destroyed ancient treasures in the city of Timbuktu and prohibited anyone from playing music under threat of death. As VOA’s Greg Flakus reports from Austin, some are afraid to return to their hometowns even though the jihadists are no longer in control there.
Video

Video Ebola Vaccine Trials Underway in West Africa

Ebola has claimed the lives of more than 10,000 people in West Africa. Since last summer, researchers have rushed to get anti-Ebola vaccines into clinical trials. While it's too early to say that any of the potential vaccines work, some scientists say they are seeing strong results from some of the studies. VOA's Carol Pearson reports.
Video

Video Philippines Wants Tourists Spending Money at New Casinos

Tourism is a multi-billion dollar industry in the Philippines. Close to five million foreign visitors traveled there last year, perhaps lured by the country’s tropical beaches. But Jason Strother reports from Manila that the country hopes to entice more travelers to stay indoors and spend money inside new casinos.
Video

Video Civilian Casualties Push Men to Join Rebels in Ukraine

The continued fighting in eastern Ukraine and the shelling of civilian neighborhoods seem to be pushing more men to join the separatist fighters. Many of the new recruits are residents of Ukraine made bitter by new grievances, as well as old. VOA's Patrick Wells reports.
Video

Video Cambodian Land Grabs Threaten Traditional Communities

Indigenous communities in Cambodia's Ratanakiri province say the government’s economic land concession policy is taking away their land and traditional way of life, making many fear that their identity will soon be lost. Local authorities, though, have denied this is the case. VOA's Say Mony went to investigate and filed this report, narrated by Colin Lovett.

VOA Blogs

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