Zigzag (IMAGE) University of Washington Caption Trails used by humans exhibit zigzags, or switchbacks, when they traverse steep hillsides, such as this on in Mallorca, Spain. Credit Martin Llobera Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.