Inspired by their childhood adventures on the windswept Minnesota prairie, two brothers grew to be internationally known naturalists and nature writers. Together with their wives — who were sisters and equal partners in the environmental work — the foursome became influential in causes including the Wilderness Act of 1964 and the Arctic National Wildlife Refuge, and their work took them around the world.

Olaus and Adolph "Ade" Murie were born in Moorhead 10 years apart to different fathers at the tail of the 19th century. Their mother, Marie, suffered three children not surviving infancy and her two spouses dying before Olaus was 9. She raised the two boys and a third son on her own.

A work ethic and love of the land not uncommon to Norwegian immigrants led the boys to become the only two brothers to win the prestigious John Burroughs Medal for the best nature writing of the year (Olaus in 1955 for illustrations, Ade in 1963 for writing).

The expanse of late 19th-century prairie beyond Moorhead became their childhood playground. They built a leaky canoe with barrel staves and flour sacks and paddled the Red River of the north.

"Many of us who travel in wilderness have not been burdened by large bank accounts," Olaus recalled.

Meanwhile, a half-continent away, two girls born nine years apart to different fathers were raised in a two-room log cabin at the edge of Fairbanks, Alaska. Margaret "Mardy" Thomas and Louise "Weezy" Gillette (their mother had divorced and remarried) could match Olaus and Ade rural hardship for rural hardship and rugged adventure for rugged adventure.

Mardy became the first woman to graduate from the University of Alaska, in 1924, and Weezy earned a botany degree from the University of Michigan, where the Murie brothers were awarded graduate degrees.

Ade gained fame for his study of wolves at Mount McKinley (now Denali), where he spent 25 summers with Weezy.

"The work necessitated a large amount of hiking and climbing. In 1939 I walked approximately 1,700 miles," he wrote.

Weezy remembered different walks: "So I went along, and took the [three] children," she told an interviewer. "That was a saga in itself, living in a ranger cabin without running water. There was a stream about 150 yards away. Ade said he carried enough water to wash enough diapers to stretch around the bounds of McKinley Park."

Her sister was asked whether it was hard to raise her own three children in the wilderness. "My answer to that is always to think of all the things I didn't have to do, like go to bridge parties or answer the phone or wax the floor," Mardy said.

The two families ended up on ranches in Wyoming and did scientific work across the western United States and beyond. A catalog of the family's accomplishments is lengthy, with popular books, reports, research articles and speeches on the list, as well as political involvement with the Wilderness Society and preservation causes such as Denali National Park and the Jackson Hole (Wyo.) Conservation Alliance. Their work took them to countries including Norway, New Zealand and Uganda.

"I hope it will be a long, long time before man can spoil it all," wrote Mardy.

An 'Olaus' Christmas

Christmas at the ranch was a special time for the families. Olaus would trim the stump from a dead tree, nail it to a stand and drill holes in it. He collected discarded boughs of conifers from logged forests and jam them into the holes, like a fake tree. They called it an "Olaus Tree."

He said, "One cannot describe a Christmas Eve around a fireplace. There is so much feeling in it. There were 10 of us, happy to be together. Beside the fireplace is the lighted tree — as usual, handmade by me from limbs from various large trees here in the woods. Ade and I never cut a living tree."

The brothers espoused an ecosystem approach to biological systems at a time when single-species science was dominant. Life magazine called Olaus "a 20th-century Thoreau."

"Poisoning and trapping of so-called predators and killing rodents, and the related insecticide and herbicide programs, are evidences of human immaturity. The use of the term 'vermin' as applied to so many wild creatures is a thoughtless criticism of nature's arrangement of producing varied life on this planet," Olaus wrote.

Ade was particularly detailed: One winter he collected 18 samples of moose scat and calculated that the average moose's bowel movement was 128 droppings, with a range of 78 to 192.

The Wilderness Act, supported by the Muries, banned development on millions of acres in national forests, parks and other land. Mardy was present in the White House Rose Garden when President Lyndon B. Johnson signed the act in 1964. Sadly, Olaus had died of cancer a few months before.

A few years after Olaus' death, the Moose, Wyo., ranch was sold to the National Park Service to be incorporated into Grand Teton National Park. Honorary degrees, awards and other kudos flowed to the Muries in their twilight years. Mardy was awarded the Presidential Medal of Freedom in 1998 by President Bill Clinton. The Murie Ranch in Grand Teton National Park was designated a National Historic Landmark in 2006.

The rugged outdoor life agreed with the sisters. Mardy died at age 101 in 2003; Weezy lived to be 100. Her obituary in the Fairbanks newspaper said Weezy was "the last surviving member of a family foursome that helped change Alaska."

Mark Neuzil is chairman of the Department of Emerging Media at the University of St. Thomas in St. Paul and the author of several books on the environment.