By using common factors of physics: weight, gravity, and stability.
Weight would keep them at a constant height.
Gravity helps the weight and how much force it propels the person, or objects, into the air.
Stability helps adjust how much distance the person, or object, needs to be.
The part that it played was in the changing of the environment/climate for the organisms that live on those continents. And the part it could've played was the way that the organisms had to adapt to that climate and it stayed that way over generations.
