Scientists say they may have worked out how spiders and silkworms are able to produce such strong fibers to spin their webs and cocoons. They say that if they are right, their research could be used to produce silk in the laboratory for extra-strong protective clothing, sports equipment and even replacement bone tissue. Silk is the strongest natural fiber known to man but scientists have yet to replicate its strength. They have managed to purify silk into powder but have not been able to turn it into material. "The problem is that when people take these purified powders and try...