Advanced theories why spiders defy gravity?

So, spiders(and others) have tiny hairs or scopulae that adhere to surfaces enabling them to 'stick' to walls and ceilings. What is so special about the hairs on spiders legs as opposed to humans? I have hair on my arms/legs/torso, so why can't I adhere to a vertical surface? Do spider's minute hairs/scopulae produce adhesive chemicals? Or is there something else that makes spiders follicles more anti-gravitational than human's?

Advanced theories why spiders defy gravity?

Perfect example for the misuse of the word theory. Not a single person answering this question could have a theory about spiders. Opinions yes, theories no. Theories are derived by testing hypothesis. Nobody answering this question is doing research on spiders and has reams of data to support their research.

Besides we know why insect, bugs and spiders can crawl up walls and hang upside down. http://www.sciam.com/print_version.cfm?a...

Advanced theories why spiders defy gravity?

Insect hairs, and geckos have similar ones, are a lot more stiff and brittle. Also, because they are so small (Think about 1% of a human hair), they are more easily able to grab into a surface.

Advanced theories why spiders defy gravity?

Well first of all the force of gravity is a function of mass as well, so being as small as they are, they already have a decided advantage in defying gravity. The tiny bristles also called setae are very stiff and often densely packed, thereby making a large surface area for adhesion. Most of these bristles are also electrically charged, thereby making an electromagnetic gradient as well, this especially helps when climbing glass. However the success of most insects and spiders is due to many morphological adaptations, one being apical claws and what are known as pulvilli. The claws make climbing rough surfaces very easy, and the pulvilli which are modified pads of those dense hairs mentioned earlier are great for adding more traction.

Hope this helps!