Via the New York Times, I found a new paper in The Journal of Experimental Biology that possibly has lessons for humans. The lessons are about how to walk over slick surfaces without falling. And although it’s coming a little late in the season, it’s good advice to remember for next winter.
The authors ran four helmeted guinea fowl (Numida meleagris) over tracks, training them on tracks with a sandpaper segment, providing good traction. Then they let the birds run over both sandpaper tracks and tracks with a slick segment made of polypropylene. As you might guess, some of the birds slipped. Here are some recordings; be sure to watch them since they’re short and LOLzy:
Video 1: Control birds on sandpaper track
Video 2: Experimental trial, polypropylene. Bird crosses successfully
Video 3: Experiment trial, polypropylene. Bird falls on its tuchus. Note that in this case the bird had its front leg extended forward more than the previous bird.
Here’s the successful bird in a screenshot from video 2:
The crucial graph: the “fall zone” occurs when the upper segment of the limb is at an angle of less than 70 degrees from the ground (legs right below you are 90 degrees). The plot, taken from the paper, shows speed versus limb contact angle, SP = sandpaper, PP = polypropylene, dots are successful runs, triangles are falls (FAIL!).
What you should learn from this: when crossing a slick piece of ground, especially ice, keep your steps short and your legs below the body, mincing rather than marching across. Actually, this had previously been shown in several studies of human locomotion, but how many of us knew about those?
Clark, A. J. and T. E. Higham. 2011. Slipping, sliding and stability, locomoter strategies for overcoming low-friction surfaces. J. Exp. Biol. 214:1369-1378.