martes, 6 de marzo de 2012

Prehistoric Humans and Changing Climate Worked Together to Kill Off Great Ice Age Mammals

Results of recent study have implications for modern humans and the management of animal populations around the world.

It turns out that prehistoric human hunters of the Ice Age had significant help from the weather when it came to driving the big mammals, like mammoths and mastodons, to their extinction.

So reports the authors of a new study published in the Proceedings of the National Academy of Sciences (PNAS).

To reach this conclusion, researchers at the University of Cambridge assessed the relative importance of a number of factors that may have contributed to the extinctions of Quaternary period (700,000 BP to present) large megafauna, animals that were 44 kg or larger. These megafauna included mammoths, mastodons and giant sloths in the Americas, mammoths of Eurasia, the moas (giant flightless birds in New Zealand), wombats and giant kangaroos of Australia, and woolly rhinos in Europe. They conducted a statistical analysis of climatic information from an Antarctic ice core representing the last several hundred thousand years, coupled with data related to the arrival or emergence of modern humans across five landmasses -- North America, South America, Eurasia, Australia and New Zealand, and the known extinction data of these various megafauna.
Their analysis suggested that it was actually the combination of hunting and/or habitat destruction caused by modern humans, and climate change, that caused the extinctions. Moreover, the researchers assert that the study has important implications for the consequences of how human and climatic pressures are affecting large mammals living today, such as polar bears, elephants, tigers and rhinos, among others.

Says Professor Rhys Green, one of the study authors: "Most previous studies have argued that the extinction of mammoths and other megafauna is linked separately to either human pressure or climatic change. Our work indicates that they had their devastating effect working together. This previous combination of unusual patterns of climate change and direct human pressure from hunting and habitat destruction is similar to those to which we are subjecting nature to today and what happened before should be taken as a warning. The key difference this time is that the climate change is not caused by fluctuations in the earth's rotation axis but to warming caused by fossil fuel burning and deforestation by humans - a double whammy of our own making. We should learn the lesson and act urgently to moderate both types of impact."

The paper, entitled 'Quantitative global analysis of the role of climate and people in explaining late Quaternary megafaunal extinctions', is published in the March 5, 2012 edition of the PNAS.

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