No matter how far you go back in the history of human evolution—actually, in the history of all living organisms on planet Earth—there has been one constant factor.
The size of a single biological cell is inversely proportional to the strength of the gravitational field extended on the cell (from Wikipedia).
Stronger gravitational field? Smaller cells.
Weaker gravitational fields? Larger cells.
Gravity is a limiting factor in growth of all organisms—our movement as human has taken gravity into account since the beginning. We are a function of gravity.
The obvious example for humans is the high jump (current record is a shade over 8 feet, set in 1993!). The measure is truly a battle against gravity.
But gravity can also be used to an animal’s advantage, as Jon Zahourek points out in this video involving the horse. (For an illustration to accompany this video, check this post from a website called Horse Talk.)
Gravity isn’t a ‘thing’ you can see. But you can certainly witness its impact on all living things. It’s in the motion. And the muscles. And the design.