The study provides the first direct experimental evidence that gecko setae adhere to surfaces through van der Waals forces, rather than capillary adhesion. Geckos have evolved a highly effective adhesive system using millions of tiny foot hairs. The researchers tested the capillary and van der Waals hypotheses by measuring the adhesion forces of live gecko toes and isolated setae on hydrophobic and hydrophilic surfaces. They found that adhesion was equally strong on both types of surfaces, supporting the van der Waals hypothesis. The study also rejected the idea that water contact angle predicts attachment forces, as geckos failed to adhere to hydrophobic, weakly polarizable surfaces. The results suggest that the adhesive properties of gecko setae are primarily determined by the size and shape of the tips, not surface chemistry. The findings have implications for the design of synthetic adhesives, indicating that increasing surface density through subdivision of structures can enhance adhesion. Physical models of synthetic setal tips fabricated from different materials confirmed the effectiveness of van der Waals forces in achieving strong adhesion.The study provides the first direct experimental evidence that gecko setae adhere to surfaces through van der Waals forces, rather than capillary adhesion. Geckos have evolved a highly effective adhesive system using millions of tiny foot hairs. The researchers tested the capillary and van der Waals hypotheses by measuring the adhesion forces of live gecko toes and isolated setae on hydrophobic and hydrophilic surfaces. They found that adhesion was equally strong on both types of surfaces, supporting the van der Waals hypothesis. The study also rejected the idea that water contact angle predicts attachment forces, as geckos failed to adhere to hydrophobic, weakly polarizable surfaces. The results suggest that the adhesive properties of gecko setae are primarily determined by the size and shape of the tips, not surface chemistry. The findings have implications for the design of synthetic adhesives, indicating that increasing surface density through subdivision of structures can enhance adhesion. Physical models of synthetic setal tips fabricated from different materials confirmed the effectiveness of van der Waals forces in achieving strong adhesion.