Sheep do it. Goats do it. Trekkers climbing steep hills by instinct do it . . .

But only now have academics investigated why we create zigzags when we climb hills - and why, when it can mean walking 20 times as far, a zigzag is faster than the shortest distance between two points. Writing in the Journal of Theoretical Biology, they explain that zig-zagging requires less puff.

Marcos Llobera, Assistant Professor of Anthropology at the University of Washington, and Tim Sluckin, Professor of Applied Mathematical Physics at the University of Southampton, developed a mathematical model showing that a zigzag provides the most efficient way for humans to go up or down steep slopes.

Professor Llobera, who is interested in reconstructing patterns of movement within past landscapes, and how landscapes have resulted from the accumulations of various societies and cultures, said that his study stemmed from research into the emergence of trail systems on flat terrain.

“When you have changes in elevation it makes things more complicated,” he explained.

“There is a point where it becomes metabolically too costly to go straight ahead, so people move at an angle. Eventually, they need to go back toward the direction they were headed and this creates zigzags. The steeper the slope, the more important it is that you tackle it at the right angle.”

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