Cosmos Offers Clues to the Fate of Humans on Earth
By Marlene Cimons
Astrophysicist Adam Frank sees climate change through a cosmic lens. He believes our present civilization isn't the first to burn up its resources—and won't be the last. Moreover, he thinks it's possible the same burnout fate already might have befallen alien worlds. That's why he says the current conversation about climate change is all wrong. "We shouldn't be talking about saving the planet, because the Earth will go on without us," he said. "We should be talking about saving ourselves."
A professor of physics and astronomy at the University of Rochester, Frank says viewing climate change in the context of astrobiology—the study of life in a planetary framework—raises important new questions that could better define our destiny in a warming world. All civilizations increasingly deplete their assets as their populations grow, altering environmental conditions along the way. Climate change shouldn't come as a surprise to anyone, he said—it's the inevitable result of a civilization reveling in its own success.
"This is a big universe, and I don't know how long civilizations last," Frank said. "We're just one of them. Some of them almost certainly burned themselves out. Life has driven profound changes in climate a number of times in Earth's history, and we're the one that's happening now. We should have expected climate change knowing what we know about how climate change works. Any civilization will drive their planet into an Anthropocene," he said, referring to an age when human activities have a profound influence on climate and the Earth's ecosystems. "Knowing this changes entirely how we should frame climate change, and how we talk about it."
First, the denial and finger-pointing must end, he said. "We have to stop the blaming and the human-hating, because the Earth will just move on, with or without us," he said. "We didn't trigger climate change on purpose. It was an accident. Any technological civilization that evolves on any planet cannot help but trigger climate change. Climate change is not our fault. Not doing something about it—that will be our fault."
Dinosaur footprint in Spain. Pixabay
If we accept that life on Earth as we now know it is an experiment of the biosphere, then allowing climate change to destroy us will only enable another experiment to take its place, he said. When all the dinosaurs died more than 65 million years ago, for example, other species evolved and moved in—including us. That's how the biosphere works.
"After the mass extinction of the dinosaurs, your ancestor mammals survived," Frank said. "Earth just filled all the niches. We're here because of it. The biosphere has run a lot of experiments, and we're just the latest. Humanity is what the biosphere is doing right now. If we don't make it, we become the agent for the next round of the biosphere's experiments. What we have to figure out is how to still be what the biosphere is doing thousands of years from now."
Frank and his collaborators—including Jonathan Carroll-Nellenback, a senior computational scientist at Rochester, Marina Alberti of the University of Washington, and Axel Kleidon of the Max Planck Institute for Biogeochemistry—developed a series of mathematical models to illustrate civilization's potential responses to the dangers of climate change, and what could happen.
Above: The Maya civilization, hailed for its advancements in architecture, agriculture, math and engineering, peaked during the first millennium AD, when it stretched from present-day Mexico to Guatemala and Belize. Evidence indicates climate change in the Yucatán fueled famine, leading to its decline.
They designed their models based in part on case studies of extinct civilizations, including the story of the inhabitants of Easter Island, a Chilean island in the southeastern Pacific Ocean. People began to colonize the island between 400 and 700 AD, and the population grew to 10,000 sometime between 1200 and 1500 AD. By the 18th century, however, after residents used up their resources, the population plummeted to about 2,000 people.
"This is an island in the middle of nowhere," Frank said. "They overused their resources. Once they did that, they couldn't go anywhere. If you've cut down all your trees, you can't build canoes and leave."
Their work appears in the journal Astrobiology. Also, Frank has authored a new book—Light of the Stars: Alien Worlds and the Fate of the Earth—which draws upon this study and explores the dimensions of climate change in a vast universe.
Statues on Easter Island. Pixabay
In their study, the authors lay out four possible scenarios:
- Die-off. This is when the population and the state of the planet—its average temperature, for example—increase rapidly. Eventually, the population peaks, then drops quickly as temperatures make it more difficult to survive. The planet reaches a steady population level, but it represents only a fraction of the peak. "Imagine if seven out of ten people you knew died quickly," Frank said.
- Sustainability. Here, the population and the temperature rise, but both eventually reach steady levels without catastrophic consequences. Once people realize the bad effects of using high-impact resources, such as coal and oil, and switch to low-impact resources, such as solar energy and other renewables, everything stabilizes and life goes on with no further harm.
- Collapse without resource change. This occurs when people don't act. The population and temperature both rise rapidly until the population reaches a peak. Then the population drops precipitously. Civilization collapses, although it is unclear whether the species dies out completely.
- Collapse with resource change. The population and temperature increase. People recognize the potential catastrophe and make the switch—but it's too late. Civilization collapses anyway.
"The last scenario is the most frightening, although we can be an example of any of them," Frank said. "As to what is the most likely for us—at this point, I have no idea."
Above: Between 3,000 and 3,900 years ago, the Indus Valley civilization represented 10 percent of the world's population. It is believed that this ancient civilization suffered from gradual changes in rainfall that created food shortages for its 5 million people.
It's important to be mindful of the broader perspective, he says, that past civilizations outside our realm, but similar to ours, might have endured for several centuries before succumbing to the climate change they created. "Most planets have climates, most planets have atmospheres," he said. "Knowing what we know, we should expect climate change. Any civilization will drive their planet into an anthropocene."
Thus, "if we are not the universe's first civilization, that means there are likely to be rules for how the fate of a young civilization like our own progresses," he added. "Any young population, building an energy-intensive civilization like ours, is going to have feedback on its planet. Seeing climate change in this cosmic context may give us better insights into what's happening to us now—and how to deal with it."
Reposted with permission from our media associate Nexus Media.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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