“Sentinel Species of the Anthropocene” –Are We Among Them? (Weekend Feature)


Blue Whale


Humans are the only species on our planet that has contemplated the most minute reaches of the fabric of space, the origins of the cosmos, the nature of time, the phenomenon of black holes, and the workings of our own thought processes. Here, on the edge of what we know, says physicist Carlo Rovelli, “in contact with the ocean of the unknown, shines the mystery and the beauty of our species and the world. And it’s breathtaking.”

Who knows how many and which other extraordinary complex lifeforms exist or once existed, in forms perhaps impossible for us to imagine, in the endless spaces of the cosmos, asks Rovelli. “There is so much space up there that it is childish to think that in a peripheral corner of an ordinary galaxy there should be something uniquely special. Life on Earth gives only a small taste of what can happen in the universe. ”

We are a species the only one left of a group of species (the genus Homo) that have already become extinct—some, like the Neanderthals, quite recently, roughly thirty thousand years ago. It is a group of species, writes Rovelli that evolved in Africa and left to explore new worlds, and went far: as far, eventually, as Patagonia—and as far, eventually, as the moon, and soon, perhaps Mars and beyond.

If we’re not the universe’s first planet-spanning civilization, says physicist Adam Frank, “that means there are likely to be rules for how the fate of a young civilization like our own progresses.” Our Anthropocene civilization is just the current stage of Earth’s ongoing evolutionary experiments.

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But are we doomed as a species? Rovelli thinks so: I believe, he says, “that our species will not last long. It does not seem to be made of the stuff that has allowed the turtle, for example, to continue to exist more or less unchanged for hundreds of millions of years, for hundreds of times longer, that is, than we have even been in existence. We belong to a short-lived genus of species. All of our cousins are already extinct. What’s more, we do damage. The brutal climate and environmental changes that we have triggered are unlikely to spare us.”

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Perhaps extinction is embedded in life’s equation in the cosmos. If a civilization emitted radio signals from the other side of the galaxy, when the signal arrives here, the civilization will already be dead, says physicist Claudio Grimaldi, of the Federal Polytechnical School of Lausanne in Switzerland. In an effort to update the 1961 Drake Equation, which estimates the number of detectable, intelligent civilizations in the Milky Way, physicist Claudio Grimaldi and colleagues calculated the area of the galaxy that should be filled with these ghost signals at a given time.

The team assumed technologically savvy civilizations are born and die at a constant rate. When a civilization dies out and stops broadcasting, the signals it had sent continue traveling like concentric ripples on a pond.

How can you really compare the great extinction events in Earth’s geologic past, which occur over such vast timescales, to what’s going on today, which is centuries at the longest? asks MIT’s Daniel Rothman.

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Dinosaurs may have ruled the land 66 million years ago during the Cretaceous period but the oceans belonged to the ammonites. But volcanic activity and climate change already placed ammonites under stress. The asteroid impact that ended the dinosaurs’ reign provided the final blow. Only a few dwindling species of ammonites survived. Today, the ammonites’ oldest surviving relative is the nautilus. Will it survive the sixth great extinction? Will the whales and marine mammals? Will the human species?

“Marine mammals, such as manatees or bottlenose dolphins, are sentinel species—the canary in the coal mine,” says Nathan Clark, associate professor in Pitt’s Department of Computational and Systems Biology, and the Pittsburgh Center for Evolutionary Biology and Medicine. “If you follow their health, it will tell you a lot about potential environmental issues that could eventually affect humans.”

When a group of small, hoofed mammals slid into Earth’s blue estuaries during the Eocene Epoch, they gradually evolved into today’s whales and dolphins becoming color-blind and losing their sense of smell and taste. And they also lost critical gene called PON1 that makes them vulnerable to ocean-born pesticides, says Clark.

But they also face, along with human species, a far greater threat, says Clark.

Our blue planet is in the grips of the Sixth Mass Extinction: the best-case scenario projects that humans will add 300 gigatons of carbon to the oceans by 2100, while more than 500 gigatons will be added under the worst-case scenario, far exceeding the critical threshold, according to Daniel Rothman professor of geophysics and co-director of MIT’s Lorenz Center. By 2100, the carbon cycle will either be close to or well beyond Earth’s threshold for catastrophe.

“The predictions Daniel Rothman makes would have grave consequences for most of life on Earth,” Clark said in an email to dailygalaxy.com. “The rapid warming would cause major environmental changes that smaller, more fragile populations of species may not be able to keep up with adaptively. In addition to the loss of land area by rising ocean levels, marine ecosystems could also change, such as through the shifting or halting of major ocean currents. Current changes would have major impacts on food sources for whales and other marine predators. These major ecosystem changes would be a much larger concern than the loss of the PON1 gene.”

We are perhaps the only species on Earth to be conscious of the inevitability of our individual mortality, says Rovelli. “I fear that soon we shall also have to become the only species that will knowingly watch the coming of its own collective demise, or at least the demise of its civilization.

“As we know more or less well how to deal with our individual mortality, so we will deal with the collapse of our civilization. It is not so different. And it’s certainly not the first time that this will have happened. The Maya and Cretans, among many others, already experienced this. We are born and die as the stars are born and die, both individually and collectively. This is our reality. Life is precious to us because it is ephemeral.”

The Daily Galaxy via University of Pittsburgh Schools of the Health Sciences, MIT, PLOS 1, The Atlantic, and Carlo Rovelli, Seven Brief Lessons on Physics (pp. 81-82). Kindle Edition.


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