The researchers say blood samples they took from the Dukha's herds, which have now been analyzed independently by scientists in Canada, cast doubt on the theory.
Other wildlife veterinarians disagree, however, arguing that untreated disease and inbreeding have culled the reindeer population. (Read related article.)
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Olson said, "Although heterozygosity [a measure of genetic variation] was low, if compared to free-ranging caribou [wild reindeer] it is not lower than other wild healthy populations in parts of Asia and North America. This is not low enough that one would expect to see any signs of immune system deficiencies or reduction of fertility. In fact, the herders estimated that all of their adult females conceived last winter."
There have been moves to import animals from Scandinavia and elsewhere in an attempt to introduce new blood to the Dukha reindeer herds. Olson, however, cautions against this.
He said low genetic diversity is a natural part of the domestication process and that Dukha reindeer are selected for traits such as passiveness and strong backs that support saddles and riders.
Olson said herders told him that wild reindeer bulls sometimes mated with the domesticated reindeer, but the offspring were aggressive and had weak backs. "These deer were useless and killed," he said.
Sardar and Olson believe the real causes of declining herds are linked to social changes following the collapse of communism in Mongolia 15 years ago and emerging pressures on the northern taiga. For instance, the pair found that herds often didn't have enough fertile females to keep numbers stable.
Sardar said, "The younger generation of Dukha who brought the reindeer back from the defunct state farms had probably lost the wisdom of breeding after 50 years of communism."
And as herders move away from the taiga to take advantage of new schools and medical facilities in towns, Sardar said their reindeer are denied rich summer grazing in mountain pastures. "They may not be getting the proper nutrition they need," he added.
But what most concerns Sardar and Olson are threats to the Dukha's traditional taiga heartlands.
They say an upsurge in commercial hunting for deer, wild boar, moose, and other animals has meant that wolves now have to search for alternative prey. "Most families we talked to in the taiga complained about wolves," Sardar said. "In fact, wolf predation seemed to be the principal cause of fatality among the herds."
And like Ghosta, other Dukha are forced to eat their own animals as subsistence hunting becomes more difficult, Sardar said.
"Everyone said the wildlife is being wiped out," Olson added. "Instead of a one-day trip to the hunting grounds, people said they were now away four to five days and at times forced to cross into Tyva," a neighboring republic in the Russian Federation.
Olson said some Dukha have told him that ibex and argali sheep have both disappeared within the last 15 years since the arrival of Chinese traders who traffic in animalparts.
Olson said other targets include brown bears, sought for their gall bladders and paws; red deer, culled for antlers, tails and penises; and musk deer, killed for their musk glands.
"With both men and wolves eating reindeer, the rate of loss is greater than the herds' reproductive rate," Sardar said.
He cautions that the discovery of gold in parts of Mongolia's northern and western taiga may also threaten the Dukha. Sardar said mining rights have already been sold by government to politically powerful holding companies.
"For a cash-starved developing nation like Mongolia, the taiga appears more as an untapped source of income than a conservation priority," he said.
Nor, he said, is the Mongolian taiga taken sufficiently seriously at an international level. "Wildlife conservationists don't consider the taiga to be a primary concern, because it is devoid of rare and exotic species."
Sardar advocates the creation of a wilderness reserve covering some 70,000 square kilometers (27,000 square miles). Taking in the Dukha's traditional territory, this area would extend into neighboring Tyva.
It's only by conserving the taiga's wildlife, Sardar said, that the Dukha's ancient and extraordinary culture can be saved.
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