Study: Humans ‘Almost Entirely Responsible’ For Mammal Extinctions


Sep 10, 2020


Image Credit: Marizilda Cruppe

A new study claims that human activity is “almost entirely responsible” for mammal extinctions in the past 126,000 years — with human beings being the “main driver” of these extinctions.

Published in Science Advances this week, the study examined a large dataset of fossils, which provided evidence for the timing, as well as the scale, of recent extinctions. And using the Bayesian system of statistical modelling, the researchers attempted to understand whether extinctions of mammals during the past 126,000 years were more attributable to anthropogenic, or to climatic, factors. The results show that human population density alone explains mammalian extinction patterns with 96% accuracy, while human land occupation predicts the extinctions with a 97.1% accuracy. Climate predictors, on the other hand, led to much lower accuracy values.

“The causes of extinctions are more complex and are not expected to be fully dependent on a single variable. Yet, our results show that human population growth and associated processes had a strong effect on mammal extinctions, while global climatic patterns, such as the last glacial maximum, leave no statistically detectable trace in the extinction record,” the study noted. The study attributes this to “intensive hunting pressure, land use, ecosystem modifications, e.g., through the use of fire, and several cascading effects that result from human impact on the natural world.” However, the finding that is especially alarming is that the current extinction rates appear to be 1,700 times higher than those at the beginning of the Late Pleistocene, or the upper paleolithic age of human development — the 351 extinctions that took place in the last 126,000 years, can, at the current level of threat, repeat in just 810 years.

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But, “the extinctions that have occurred in the past centuries only represent the tip of the iceberg, compared to the looming extinctions of the next decades,” the study notes. At the current level of threat, it predicts 558 mammal extinctions by 2100. And, so far, scientists have already predicted that we are on the brink of the sixth mass extinction of wildlife, accelerated by man-made threats like climate change and habitat destruction. Last year, an intergovernmental panel of 145 experts from 50 countries, had also predicted that one million plant and animal species are facing the threat of extinction, at rates more accelerated than ever seen before in human history.

However, experts believe it might not be too late yet. “Reconstructing our past impacts on biodiversity is essential to understand why some species and ecosystems have been particularly vulnerable to human activities — which can hopefully allow us to develop more effective conservation actions to combat extinction,” Professor Samuel Turvey of the Zoological Society of London, who co-authored the study, told BBC. By ramping up our conservation efforts, and actively combatting this global emergency, we can still improve the situation, the researchers believe, hopeful that the “grim” and “alarming” projections will “foster increased realization on the urgency and scale of the conservation efforts” that would be required to safeguard mammalian diversity.

“When humanity exterminates other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system. The conservation of endangered species should be elevated to a global emergency for governments and institutions, equal to the climate disruption to which it is linked,” Professor Paul Ehrlich, American biologist and President of Stanford University’s Center for Conservation Biology, had told The Guardian in June, adding: “Extinction breeds extinctions.”


Written By Devrupa Rakshit

Devrupa Rakshit is an Associate Editor at The Swaddle. She is a lawyer by education, a poet by accident, a painter by shaukh, and autistic by birth. You can find her on Instagram @devruparakshit.


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