Starship Asterisk*

[i]Credit: Kellar Autumn and Steve Scherf; (inset) Kellar Autumn[/i]

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For most people, bad hair days happen when it's humid. For geckos it's the opposite. Humidity bolsters their climbing skills by making the tiny hairs on their feet stick more tightly. In the past, some researchers speculated that the lizards stick so well to walls and other objects because their feet bond to these surfaces via strong bridges of water. But new research published today in the Journal of Experimental Biology indicates that geckos need no such aid. Scientists pulled sticky hairs from geckos' soles, ramped up the humidity, and moved them over two separate surfaces: a water-attracting silica glass slide and a water-repelling gallium arsenide wafer. The tiny hairs stuck just as tightly to the water-hating as the water-loving material, indicating that geckos don't need extra water on the surface. Instead, the trick lies in the humid air: humidity makes the hairs on a gecko's feet softer and stickier, allowing them to stick to walls a bit like a used piece of chewing gum.