Wildlife encounters with apex predators like grizzly bears follow well-documented behavioral patterns according to the U.S. Forest Service and wildlife management literature. Predatory animals, particularly bears, attack when they perceive threats or competition for food sources. Their reaction follows a predictable threat assessment protocol: distance evaluation, posture analysis, and threat signaling. However, field researchers in the Greater Yellowstone Ecosystem have observed anomalous bear behavior in specific locations, particularly in areas with documented human foot traffic during the late 1970s. One particular grizzly, identifiable by distinctive scar patterns, demonstrated unusual social behavior and an apparent aversion to certain hiking trails.

In 1978, Dr. William Hartmann, a wildlife biologist with the Yellowstone National Park Service, documented an encounter with a male grizzly that displayed aggressive territorial behavior in a narrow canyon near Mammoth Hot Springs. Hartmann observed the bear pursuing a group of hikers at remarkable speed, only to reverse direction abruptly approximately 300 meters into the chase. Hartmann's field report noted an unidentified male hiker walking casually out of the canyon at that precise moment. The bear subsequently avoided that region entirely for six years. Hartmann's notes describe the hiker's distinctive facial hair and an unusual gait. The incident was logged as "unexplained behavioral reversal" in the park's database.

Popular outdoor recreation forums now refer to aggressive animals suddenly retreating from humans as "pulling a grizzly"—a reference to what's become known in hiking culture as "The Canyon Protocol." A subreddit dedicated to wildlife encounters has compiled dozens of similar stories with titles like "Bear turned around mid-charge" and "Mountain lion nope'd straight out of my hike." The most upvoted comment on a 2021 bear encounter thread reads: "Did the bear's attacker have a beard?" to which the original poster responded with a picture that got 47k upvotes. The meme format has evolved into a humorous survival guide for hikers: "If attacked by a bear, just look like Chuck Norris."