Terracettes Mystery Solved: Grazing Animals Shape Stepped Hillsides

Researchers have finally unraveled a century-old puzzle that once perplexed Charles Darwin and other notable scientists. The distinctive step-like ridges known as terracettes, found on steep hillsides around the world, are now understood to be formed by the repetitive grazing patterns of animals like sheep and cattle.

Benjamin Seleb, the lead author of the study published in the Journal of the Royal Society Interface, first noticed these formations during a hike in the Alps. Initially suspecting that grazing cows were responsible for the terracettes, he began developing models to test his hypothesis. The research team from Georgia Institute of Technology and the BioFrontiers Institute at the University of Colorado Boulder used computer simulations to demonstrate how animals' movement patterns can create these ordered landscape features over time.

The study involved modeling the behavior of virtual grazers on steep slopes, revealing that these animals tend to follow long, horizontal pathways due to energy efficiency. As they traverse these paths repeatedly, soil and vegetation become compacted, leading to subtle changes in the terrain. Over generations, this compaction encourages subsequent animals to follow similar routes, eventually forming the recognizable terraced patterns.

Professor Saad Bhamla, a co-author of the study from the Bhamla Lab of Extraordinary Organisms, emphasized that the findings challenge previous assumptions about the random nature of animal movement and its ability to create structured landscapes. "Our research shows that these regular formations emerge out of chaotic movements through stigmergic feedback," he explained.

This discovery not only resolves a long-standing scientific debate but also highlights how complex natural patterns can arise from simple, uncoordinated behaviors. The study provides insights into the broader influence animals have on shaping landscapes and ecosystems. Understanding this process could offer new perspectives in fields such as ecology, geomorphology, and environmental science.

The research team's findings contribute to a growing body of evidence that demonstrates how organisms interact with their environment to create intricate patterns and structures. This work has implications for understanding the ecological impacts of animal behavior and may inform conservation efforts aimed at preserving natural landscapes.