Sled dogs pull sleds for recreation and work. Image: Bob Nishikawa via Getty Images

They’re some of Earth’s most powerful athletes, traversing thousands of miles of rough terrain in sub-zero temperatures, through blinding snow, and biting winds. Sled dogs have been helping humans travel across the planet’s coldest regions for centuries , hauling supplies, people, and equipment across the snow and ice. In the process, this important role that goes above and beyond simply being “man’s best friend” could have a visible impact on their evolution.

Sled dogs may have evolved shorter legs to help them pull loads more efficiently. Currently working sled dogs and those that lived about 2,000 years ago have six percent shorter leg bones than similar species, according to a study published today in the journal iScience .…