“To the mouse and any smaller animal gravity presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bott

“To the mouse and any smaller animal gravity presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force” https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRightSize.pdf https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRig...