What if Earth's gravitational force was half of what it is now?

Assuming that humans and other living things are still here, how would this affect our world?<br><br>Would we have frogs that can jump really high? Trees that grow extremely tall?<br><br>How would it affect urban planning and building construction if a two story building could stand up to strong winds with a fraction of the effort and structural integrity? Would we have massive 50 story skyscrapers? Would it be too cloudy because of all the water vapor and dust being lifted into the atmosphere?<br><br>What about the atmosphere? Would we have more oxygen? Less oxygen? How would this affect respiration?<br><br>What about movement? Would we walk, jump, and run faster? Or slower? Would a ball travel farther and stay up longer?<br><br>How would swimming and buoyancy be affected?<br><br>What about gravity and digestion? I have heard that being in a weightless environment can affect digestion in humans and other animals.