New research adds to the growing body of evidence that humans were responsible for the extinction of megafauna such as woolly mammoths and saber-toothed cats, suggesting that this process could have started much earlier than it was I thought.
Thousands of Years A few years ago, a spectacular megafauna inhabited the continents of the world, from Eurasia and the Americas to Australasia. Many of these creatures are extinct for a long time, and scientists debate extensively how much humans play.
The two dominant theories for this wave of mass extinctions are that humans pushed these spectacular creatures to their demise, or that it was in fact the consequence of climate change around the last ice age.
Previous research has argued that human hunting pushed large mammals to disappear earlier and faster than smaller ones, a phenomenon called extinction by size, in Australia 35,000 years ago.
Significantly, the latest study states that this extinction based on actual size began in Africa at least 125,000 years ago. Led by Felisa Smith of the University of New Mexico, the researchers used fossil and rock records to conclude that, at that point, the average African mammal was already 50% smaller than those of other continents.
A crucial part of the team's research they combine these mass extinctions with the history of human migration. They discovered that as humans migrated from Africa, the average size of mammals on recently occupied continents began to shrink, often to sizes even smaller than those found in Africa.
A clear pattern emerged: the animals that survived tended to be smaller than those that did not.
"It was not until human impacts began to become a factor that large body sizes made mammals more vulnerable to extinction," said Kate Lyons of the University of Nebraska-Lincoln, author of the study with Smith. and colleagues from Stanford University and the University of California, San Diego.
"The anthropological record indicates that Homo sapiens is identified as a species about 200,000 years ago, so this happened not long after the birth of us as a species, it just seems to be something we do.
" From the point In view of the history of life, it makes sense. If you kill a rabbit, you will feed your family for one night. If you can kill a large mammal, you will feed your village, "Lyons continued, in a press release from the University of Nebraska-Lincoln.
In the research, published in the journal Science the authors state The "magnitude and scale" of extinction based on size surpassed any other in the last 66 million years.It is important to note that they claim that their research also found little evidence that climate change could have been responsible for these extinctions
"If the climate were causing this, we would expect to see these events of extinction sometimes (diverging) from human migration across the world or always aligned with clear weather events in the record," Lyons said. they do none of those things. "
Multiple studies in recent years have tried to answer what led to the mass extinction of the world's megafauna In fact, a few days later , last January, two separate studies focused on Australia reached significantly different conclusions.
An article recently published in the journal Nature Communications claimed to have evidence pointing to 85% of the megafauna weighing more than 100 pounds in southwestern Australia were extinct in a few thousand years when the humans arrived in the region.
A study in the Quarternary Science Journal meanwhile claimed that humans and the large marsupial Zygomaturus trilobus coexisted with each other in Australia for at least 17,000 years. That research claims that the spectacular creatures, roughly the size of a bull, lived until the beginning of the Last Glacial Maximum.
Interestingly, the latest study argues that the dramatic climate change caused the plains in the region to dry up, forcing the animals to have closer contact with humans. This could have meant that the creatures began to be hunted, a theory that links human activity and climate change in the destruction of a species of megafauna.
Featured image is a statue of the Colombian mammoth located at the University of Nebraska-Lincoln. Image credit: Craig Chandler, University of Nebraska-Lincoln