Climate change and human activity caused the extinction of some Ice-Age animals, such as the woolly rhinoceros, woolly mammoth and wild horses, and the near extinction of others including reindeer, bison and musk ox, says an international study.

The scientists say their study, published in the journal Nature, is the first to combine genetic, archaeological and climatic data to track the population history of six large Ice-Age mammals and can shed light on the possible fates of today's animals as the Earth continues its current warming cycle.

"Although these cold-adapted animals certainly fared better during the colder, glacial periods, they still managed to find places where the climate was just right -- refugia -- so that they could survive during the warmer, interglacial periods. Then, after the peak of the last ice age around 20,000 years ago, their luck started to run out," co-author Beth Shapiro, a biology professor at Penn State University, said in announcing the findings.

FOLLOW: Green House on Twitter

The study adds to the scientific debate about what caused the extinction of large mammals. A 2010 study by researchers at the University of Wollongong and the University of Adelaide said humans caused them in Australia, and a 2009 study said mammoths and mastodons began dying out 1,000 years before humans arrived in North America.

In the case of the woolly rhinoceros, the new study found that the species never overlapped with humans in Europe, so climate change is the main reason for its extinction. "Still, we expect humans might have played a role in other regions of the world where they did overlap with woolly rhinos," Shapiro said.

She said the evidence is much clearer that humans did influence, and not always negatively, the population sizes of the five other species -- the woolly mammoth, wild horse, reindeer, bison and musk ox.

"During the period when these animals were declining, the human population was beginning its boom, and was spreading out across not only the large-bodied mammals' cold-climate habitats, but also across their warm-climate refuges, changing the landscape with agriculture and other activities," Shapiro said.

The study says reindeer managed to find safe habitat in high arctic regions and bison, though extinct in Asia where their populations were extensive during the ice ages, are found only in North America although a related species survives in small numbers in Europe.

It says cold-adapted musk oxen now live only in the arctic regions of North America and Greenland, with small populations in Norway, Siberia and Sweden. Interestingly, the scientists say that if humans had any impact on them, it may have been to help sustain them. They note that musk oxen expanded rapidly after becoming established in Greenland about 5,000 years, despite having been a major resource for the Paleo-Eskimo population.

In addition to Shapiro, many other scientists contributed to this study from the United States as well as Denmark, Australia, Sweden, Spain, the United Kingdom, the Netherlands, Germany, Norway, Russia, China and Canada. The research was funded, in part, by the Leverhulme Trust, the Awards Fund, the Danish National Research Foundation, the Lundbeck Foundation, the Danish Council for Independent Research and the U.S. National Science Foundation.

-