“Ten One-Billionths of Cosmic History” –Past Homo Species Could Not Survive Intense Climate Change

"Ten One-Billionths of Cosmic History" --Past Homo Species Could Not Survive Intense Climate Change

 

The human experience on our pale blue dot “has lasted for less than 10 one-billionths of cosmic history surrounded by a vast lifeless space, yet we humans are congratulating ourselves,” says Peter Brannen author of Ends of the World about the current reign of humans recently named the Anthropocene –the period dating from the Atomic Age of the 1950s during which human activity has been the dominant influence on climate and the environment– “on an unearned geological legacy before we’ve proved ourselves capable of escaping the next century with our lives. And, besides, most of our proudest creations—whole cities and manufactured landscapes—will be destroyed by the ceaseless destruction of tectonics and erosion…many of the synthetic markers proposed to delineate the Anthropocene will not survive the insults of deep time.”

The Anthropocene –“Human Arrogance?”

“It’s human arrogance,” adds Brannen, to coin a epoch, the Anthropocene, that does not compare as a geological epoch on par with a yawning span of time like the Early Cretaceous, an epoch that lasted 600,000 times longer than this newly minted one, or the reign of the dinosaurs that lasted more than 225-million years. The Anthropocene, concludes Brannen, is an event, not an epoch.

 

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Past Extinctions of Homo Species

Brannen’s conclusions foreshadow a new study–“Past Extinctions of Homo Species Coincided with Increased Vulnerability to Climatic Change”– to understand the climate preferences of early humans and how they reacted to changes in climate. The study shows that despite technological innovations including the use of fire and refined stone tools, the formation of complex social networks, and—in the case of Neanderthals—even the production of glued spear points, fitted clothes, and a good amount of cultural and genetic exchange with Homo sapiens, past Homo species could not survive intense climate change,” says Pasquale Raia of Università di Napoli Federico II. “They tried hard; they made for the warmest places in reach as the climate got cold, but at the end of the day, that wasn’t enough.

“We were surprised by the regularity of the effect of climate change,” Raia says. “It was crystal clear, for the extinct species and for them only, that climatic conditions were just too extreme just before extinction and only in that particular moment.”

Warning to Humans Today

Raia notes that there is uncertainty in paleoclimatic reconstruction, the identification of fossil remains at the level of species, and the aging of fossil sites. But, he says, the main insights “hold true under all assumptions.” The findings may serve as a kind of warning to humans today as we face unprecedented changes in the climate, Raia says.

“It is worrisome to discover that our ancestors, which were no less impressive in terms of mental power as compared to any other species on Earth, could not resist climate change,” he said. “And we found that just when our own species is sawing the branch we’re sitting on by causing climate change. I personally take this as a thunderous warning message. Climate change made Homo vulnerable and hapless in the past, and this may just be happening again.”

Extensive Fossil Database

To shed light on past extinctions of Homo species including H. habilis, H. ergaster, H. erectus, H. heidelbergensis, H. neanderthalensis, and H. sapiens, the researchers relied on a high-resolution past climate emulator, which provides temperature, rainfall, and other data over the last 5 million years. They also looked to an extensive fossil database spanning more than 2,750 archaeological records to model the evolution of Homo species’ climatic niche over time.

Their studies offer robust evidence that three Homo species—H. erectus, H. heidelbergensis, and H. neanderthalensis—lost a significant portion of their climatic niche just before going extinct. They report that this reduction coincided with sharp, unfavorable changes in the global climate. In the case of Neanderthals, things were likely made even worse by competition with H. sapiens.

“Crystal Clear” –Effect of Climate Change

“We were surprised by the regularity of the effect of climate change,” Raia says. “It was crystal clear, for the extinct species and for them only, that climatic conditions were just too extreme just before extinction and only in that particular moment.”

Raia notes that there is uncertainty in paleoclimatic reconstruction, the identification of fossil remains at the level of species, and the aging of fossil sites. But, he says, the main insights “hold true under all assumptions.” The findings may serve as a kind of warning to humans today as we face unprecedented changes in the climate, Raia says.

“It is worrisome to discover that our ancestors, which were no less impressive in terms of mental power as compared to any other species on Earth, could not resist climate change,” he said. “And we found that just when our own species is sawing the branch we’re sitting on by causing climate change. I personally take this as a thunderous warning message. Climate change made Homo vulnerable and hapless in the past, and this may just be happening again.”

Source: Pasquale Raia et al. Past Extinctions of Homo Species Coincided with Increased Vulnerability to Climatic Change. One Earth. Published:October 15, 2020. DOI: 10.1016/j.oneear.2020.09.007

The Daily Galaxy, Andy Johnson via The AtlanticCell Press and Raia’s Lab

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