We all know foals look like they’re "all legs," and new research is honing in on the physical and evolutionary advantages of that lanky morphology. It's all about keeping up with the herd, say the researchers, especially for migrations.

"The long legs of juvenile horses make them able to manage the lower speeds frequently necessary for migrating," said Bruno Grossi, PhD candidate in the department of ecological sciences at the University of Chile in Santiago and primary author of a recently published study on foal morphology. "Foals have longer legs than what you would see on an adult animal of the same weight (adult pony or goat). This disproportion gives them an efficient step which allows them to have longer strides without having to add the extra work of more steps to keep up."

Grossi likened the lower-speed steps of the foal to an "inverted pendulum" model, in which a mass has to be balanced above a pivoting point.

Surprisingly, however, this model does not apply with higher speeds, according to Grossi. "In the trot-to-gallop transition, for example, leg length had little importance," he said. "This is probably due to the fact that at these speeds, aerobic capacities and muscular power are more relevant