both sides are taking the spark and using what they want. >> the back is:. >> jonathan allen, aimie parnes, it is great to have you both on the show. thanks for your time. >> straight ahead, how do more than half americans not know that humans develop from species. data dive is next. >> start with one issue ad guests on all sides of the debate. and a host willing to ask the tough questions and you'll get... the inside story ray suarez hosts inside story weekdays at 5pm et / 2pm pt only on al jazeera america >> and now a techknow minute... >> san francisco's bay bridge, an engineering marvel, built to survive the worst earthquake country has to offer. >> how close are we to one of those faultines now? >> we are very close... >> this bridge uses three inovations to fight the forces of nature. deep inside the bridge's underbelly is a hinged pipe beam built to absorb horizontal movement. at it's base, is a support structure, called a "battered pile", they stand at angles, instead of straight up and down, to better handle movements. at the top of the bridge, are shear link beems, designed to fl