DNA Study Shows Rapid Climate Shift Main Cause Of Musk Ox Decline, Not Human Hunting Pressure - AFP

[hatrack]

A team of scientists has discovered that the drastic decline in Arctic musk ox populations that began roughly 12,000 years ago was due to a warming climate rather than to human hunting. "This is the first study to use ancient musk ox DNA collected from across the animal's former geographic range to test for human impacts on musk ox populations," said Beth Shapiro, the Shaffer Career Development assistant professor of biology at Penn State University and one of the team's leaders.

"We found that, although human and musk ox populations overlapped in many regions across the globe, humans probably were not responsible for the decline and eventual extinction of musk oxen across much of their former range." The team's findings will be published in the 8 March 2010 issue of the journal Proceedings of the National Academy of Sciences. Musk oxen once were plentiful across the entire Northern Hemisphere, but they now exist almost solely in Greenland and number only about 80,000 to 125,000. According to the researchers, musk oxen are not the only animals to suffer during the late Pleistocene Epoch. "The late Pleistocene was marked by rapid environmental change as well as the beginning of the spread of humans across the Northern Hemisphere," said Shapiro.

"During that time several animals became extinct, including mammoths and woolly rhinoceroses, while others, including horses, caribou, and bison, survived into the present. The reasons for these drastically different survival patterns have been debated widely, with some scientists claiming that the extinctions were due largely to human hunting.

Musk oxen provide a unique opportunity to study this question because they suffered from a decline in their population that coincided with the Pleistocene extinctions, yet they still exist today, which allows us to compare the genetic diversity of today's individuals with those individuals that lived up to 60,000 years ago." To conduct their research, the team collected musk ox bones and other remains from animals that lived during different times - up to 60,000 years ago - and from animals that lived across the species' former range. From these remains, the scientists isolated and analyzed the mitochondrial DNA, which is useful for studying ancient population dynamics due to its rapid rate of evolutionary change. The scientists also isolated and analyzed the mitochondrial DNA of musk oxen that are alive today. They then used a Bayesian statistical approach to estimate how the amount of genetic diversity of the musk oxen populations changed through time.

EDIT

http://www.terradaily.com/reports/Musk_Ox_Population_Decline_Due_to_Climate_Not_Humans_999.html

[Kurt_and_Hunter]

1. "might suggest" would be better than "shows"

The work is interesting but hardly definitive. The finding is based on a series of assumptions about the relationship of genetic diversity and population and an unwarranted assumption that human cultures go after all animals similarly and at the same time and a bunch of other sort of suggestive stuff.

For instance, is a technique based on an assumption about the specific diversity/population really accurate within speciffic thousands of years with the dating of the fossils used adding a second tier of margin of error?

Is the theory being tested itself a straw man? (That man would trigger simultaneous population disasters in all species)

There were not that many people, and people move around, and people have cultures, hunting techniques, preferred diets...

Could climate change cause geographic separation of musk ox populations resulting in reduced genetic diversity in-group but with total population holding up (in temporarily separated populations)?

And is the finding that the musk ox had a species specific climate problem that other beasts did not have? Is the suggestion that man didn't cause the musk ox drop-off but did cause the mammoth extinction?

Bottom line, nothing proved, but a very useful addition to the argument.