New research is adding to the growing body of evidence that humans are responsible for the extinction of megafauna, such as woolly mammoths and saber-toothed cats, suggesting that this process started much earlier than normal.
Thousands of years ago Some time ago, spectacular megafauna inhabited the continents of the world, from Eurasia and America to Australia. Many of these creatures have long been extinct, and scientists are debating in detail what role humans have played.
The two prevailing theories for this wave of mass extinction are that either humans brought these spectacular creatures to extinction, or
Earlier research has argued that human hunting has caused large mammals to disappear earlier and faster than smaller ones ̵
Significantly, the latest study claims that this extinction of extinction actually 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 by that time the average African mammal was already 50% smaller than on other continents.
A crucial part of the team's research they match this mass extinction with the history of human migration. They discovered that the average mammal size in the newly occupied continents began to shrink as people emigrated from Africa, often to sizes even smaller than those in Africa.
A clear pattern emerged – the animals that survived were smaller than the animals that did not survive.
"It was not until human factors became a factor that large mammals made them more susceptible 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 in San Diego.
"The anthropological records show that Homo sapiens was identified as a species about 200,000 years ago, so it did not happen to us as a species very long after the birth of us. It just seems to be something we do.  "From the point of view of life history, 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 study published in the journal Science the authors claim that size and extent of extinction have exceeded all others in the last 66 million years, and it is important that their research has found little evidence that climate change could be responsible for these eradications.
"When the climate causes this "We would expect these extinction events sometimes (unlike) from human migration across the globe or always with clear climate events in the record," Lyons said. "And they do not do any of these things."
Several studies have attempted in recent years to find an answer to what is the mass extinction of the world's megafauna. In fact, two separate studies focusing on Australia came to completely different conclusions last January.
A recent article published in the journal Nature Communications claimed to have evidence of 85% of megafauna weight over 100 pounds in southwestern Australia becoming extinct within a few thousand years of people arriving in the region.
A study in the Quarternary Science Journal has since claimed that humans and the large marsupial Zygomaturus trilobus coexisted in Australia for at least 17,000 years. This research claims that the spectacular creatures, about the size of a bull, lived until the beginnings of the Last Glacier Peak.
Interestingly, the latter study argues that the dramatic climate change has resulted in the plains of the region drying up and the animals coming into closer contact with humans. This could have meant that the creatures were hunted, a theory that combines human activity and climate change in the destruction of a megafauna species.
Pictured image is a statue of the Columbian mammoth at the University of Nebraska-Lincoln. Picture credits: Craig Chandler, University of Nebraska-Lincoln