Hot to trot Vanderli Ribeiro Photography/Getty

Newborn piglets may totter slowly to begin with, but within 8 hours they are trotting with confidence. New evidence suggests that this ability is not something they are born with, and must largely be learned. The finding confirms that walking isn’t entirely innate, even for animals – like pigs – that need to walk soon after birth.

Animals such as humans, rats and mice are mostly helpless as newborns. Other species, particularly hoofed animals, must quickly fend for themselves. For instance, baby wildebeest can follow the herd just an hour after birth.

Newborn pigs stand and walk within minutes of birth too – but no one was sure whether they are born with all the motor skills they need to walk, or whether they develop them extraordinarily quickly.


To try to figure this out, Chris Van Ginneken of the University of Antwerp in Belgium and her colleagues followed 14 toddling piglets over the first four days of life. They filmed each piglet at the same 10 moments in their young existences, walking at their own pace across a rubber mat – used to prevent the animals slipping.

Video analysis allowed the researchers to examine the piglets’ speed and stride length, as well as how often they took steps and how long each foot spent touching the ground. The team scaled the data to correct for each animal’s growth, giving them a picture of how gaits altered with age.

From birth, the piglets knew the fundamentals of limb coordination: their feet hit the ground in the same order as in adult pigs, the team found. But this doesn’t mean they were confident walkers from birth.

Full control

In fact, the piglets walked slowly to begin with, covering about a tenth of a metre per second – but by the time they were 2 hours old, they had reached a consistent speed relative to their size. By 4 hours, the length of their stride relative to body size had stabilised. And by 8 hours, the piglets had smoothed out most mismatches between the movements of their left and right limbs, and seemed to be in full control of their walking.

“At first we were a bit puzzled by the different time points by which some variables stabilised,” says Van Ginneken. But it makes sense that a piglet needs to have its basic motor skills in place before it can fine-tune them, she says.

The results suggest that the footfall pattern of piglets is “completely innate”, the team writes, whereas the other elements of walking are not – although they develop very soon after birth.

“The work nicely shows that the coordination of locomotor movement patterns in piglets is not entirely innate, but undergoes a rapid neuromotor maturation,” says Francesco Lacquaniti at the University of Rome Tor Vergata in Italy.

The findings complement some of Lacquaniti’s research, which showed that although newborn babies have an innate ability to perform some movements associated with walking, they need time to develop other important features, like shifting the weight from heel to toe.

“The difference is the time frame in which this learning to walk is established,” Van Ginneken says. “In humans it is clearly longer.”

Journal reference: Journal of Experimental Biology, DOI: 10.1242/jeb.157693