Answer
If the center of gravity of the system is below the hips, when the body tilts in one direction or the other, the torque from gravity rotates the system back toward its equilibrium position in the middle.
Therefore, birds are more stable than humans.
Work Step by Step
If the center of gravity of the system is below the hips, when the body tilts in one direction or the other, the torque from gravity rotates the system back toward its equilibrium position in the middle.
However, if the center of gravity of the system is above the hips, when the body tilts in one direction or the other, the torque from gravity rotates the body away from the equilibrium position and the body could fall over more easily.
Therefore, birds are more stable than humans.
