CAMBRIDGE, Mass. — Many environmental advocates believe climate change is the greatest threat facing the human race today. As fears of a mass extinction event grow, a new study finds it’s already happened, at least in prehistoric times. Researchers say early humans met extinction at the hands of dramatic shifts in their environment, just like Earth is facing now.
An international team of scientists finds Homo sapiens (present day humans) are the only group of intelligent primates left standing. A study of climate models and fossil records spanning the last five million years reveals what killed at least six different species of early humans on Earth. The results show our distant ancestors could not adapt to dramatic warming and cooling temperatures — better known as climate change.
“Our findings show 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 from the University of Naples Federico II in a media release.
“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.”
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Researchers examined the extinctions of several human species including Homo habilis, ergaster, erectus, heidelbergensis, neanderthalensis, and certain groups of Homo sapiens. The team made use of a high-resolution past climate emulator; technology that maps out temperature, rainfall, and other climate data over millions of years. They also studied more than 2,750 archaeological records which show how the species’ ability to survive in certain climates evolved.
For Homo erectus, heidelbergensis, and neanderthalensis, the results are not good. According to the study, all three species suffered a significant loss in climatic niche just before dying out. Climatic niche describes the set of conditions a race is capable of surviving in. These global climate conditions all saw a sharp and unfavorable decline in the years leading up to early human extinction.
“We were surprised by the regularity of the effect of climate change,” Raia adds. “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.”
Although fossils don’t paint the entire picture of prehistoric life, researchers say the evidence points to a clear warning about the dangers of climate change for life on Earth.
“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,” the Italian researcher says. “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.”
The study appears in the journal One Earth.