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In the Great North Woods, 1,000-pound moose plagued with arthritis wander Isle Royale National Park in Michigan, a wilderness area where biologists have been conducting research for 50 years on the animals and the wolves that hunt them. The scientists’ recent research published in Ecology Letters shows that arthritis, known as osteoarthritis (AO), is not just a human affliction, but it is also found in animals and can be the result of malnutrition early in life.
"This remarkable study offers us a unique insight into the complex causes of OA," said lead researcher Rolf Peterson, a wildlife biologist from Michigan Technological University, in a press release. "The link between early nutrition and arthritis, in both people and moose, reveal that OA is more complex than commonly assumed and involves connections between physiology, life histories, populations and communities, while highlighting the importance of the disorder for past and present humans."
Since 1958, three generations of researchers have examined the predator-prey relationship on the island, collecting bones from 4,000 moose. (Most of the animals died during winter's harsh conditions or they fell victim to wolf attacks.) Of those, about 1,200 skeletons showed that the ungulates had arthritis. When the moose population was high, more of the animals suffered from the malady than when the population was smaller. This lead the scientists to hypothesize that when the population ballooned, each moose got less food. As a result, mothers produced less milk and more animals suffered from malnutrition. Young moose that didn’t get the proper nutrition developed arthritis later in life, as indicated by the small metatarsal bone in the foot.
The conclusions drawn by the scientists also shed light on how dietary changes may lead to arthritis in humans. “For people, several historical cases may suggest a nutritional link. Bones of 16th-century American Indians in Florida and Georgia showed significant increases in osteoarthritis after Spanish missionaries arrived and tribes adopted farming, increasing their workload but also shifting their diet from fish and wild plants to corn, which ‘lacks a couple of essential amino acids and is iron deficient,’” said the study's co-author, Clark Larsen, an Ohio State University anthropologist, in a New York Times article. “Many children and young adults were smaller and died earlier, Dr. Larsen said, and similar patterns occurred when an earlier American Indian population in the Midwest began farming maize,” the article went on to say.
This study is just one of many published papers that focus on Isle Royale, which seems to yield a wealth of information thanks to the length of time scientist have been conducting research there. A few years ago, Les Line wrote an article for Audubon about new developments that Peterson and his colleagues were seeing on the island due to climate change.
“The dynamics of the predator-prey relationship on Isle Royale are extremely complex, involving subtleties of weather, parasites, snow conditions, the food base,” Peterson said at the time. “That’s just for starters. Then pivotal events occur with effects that are felt for decades. Finally, each 10-year period of this study has been unique, bearing little resemblance to other decades. So we don’t put much stock in predictions anymore. That’s especially true in a world where accelerating climate change will influence virtually everything." It could also change the vegetation there, which could further affect how many moose develop arthritis. If nothing else, this recent study shows that the natural laboratory may still hold a trove of information about not only predator-prey relationships, but also how diet may have an impact on disease.