The locomotor kinematics and ground reaction forces of walking giraffes

A giraffe’s swinging neck may help it walk more economically. Its long neck is not simply a weight that the legs must carry: its movements can partly counter the body’s forward-and-backward accelerations. Testing that possibility meant measuring both the giraffe above ground and the forces beneath its feet.

Christopher Basu, Alan Wilson and John Hutchinson studied three reticulated giraffes at Whipsnade Zoo. Keepers led them over a six-metre array of force plates buried under sand while cameras recorded their strides. The team combined foot-force measurements with neck movements, then used a simplified model to examine how the neck and trunk accelerated together.

The giraffes increased walking speed mainly by taking longer steps. Their necks swung twice per stride, moving through a larger angle at faster speeds. In the horizontal direction, neck and trunk accelerations largely opposed one another, consistent with reduced mechanical work in moving the whole animal. Actual energy expenditure was not measured, and the giraffes chose only a narrow range of slow speeds. Still, the study changes how we see that moving neck: its timing may matter as much as its weight.