Study shows how baboons effortlessly transition from walking on four legs to two

Baboons are able to effortlessly transition from walking on four legs to two in less than a second without breaking their stride – despite being four-footed, scientists have found.

Researchers have uncovered the mechanism by which these primates can manoeuvre themselves into an upright posture without missing a step.

The scientists said their findings, published in the journal Journal of Experimental Biology, suggest that while the ability to walk upright on two legs – known as bipedalism – is one of humanity’s defining physical characteristics, it is not as challenging a feat as previously thought.

Study author Kris D’Aout, of the University of Liverpool, told the PA news agency: “I think that one of the big conclusions we have from all the work that we and other people have been doing is that being bipedal, at least to some extent, is probably not as hard as we used to think.

“A few decades ago, we thought that we are the only bipeds and therefore it is something really, really special.

“But this study in a non-biped, or a non-habitable biped, goes on to prove that it is actually quite feasible to be able to transition from all fours to two feet – you don’t have to slow down.”

For their study, the researchers filmed 10 olive baboons of varying ages, from infants to mature adults, including both males and females.

An olive baboon transitioning from walking on four legs to two
An olive baboon transitioning from walking on four legs to two at the primatology station of the CNRS, in France (Gilles Berillon/Francois Druelle/Journal of Experimental Biology)

The researchers used sounds, music, food, and mirrors to coax the baboons into walking upright so they could film the movements.

The team then analysed the videos, breaking the movement down to 15 body segments – including the head, body, arms and legs.

The researchers looked at individual frames to analyse how the entire body moved as each baboon manoeuvred into an upright posture in less than a second.

They found that these primates crouched their hindlimbs and sprinted them forward under the torso while taking two or three steps, lifting the body upright as they stood up to walk while maintaining the same speed moving forward.

Lead author Peter Aerts, from the University of Antwerp in Belgium, said: “These transitions looked very natural, not requiring any special attention or effort from the animal.”

The scientists then calculated the energy expended by the baboons transitioning from four to two legs.

They found that as the animals reared up, their energy consumption tripled – but the overall energy cost was still very little.

Mr D’Aout told PA: “This proves that the prerequisites to become a habitual bipedal is there in many animals, and that we humans have just exploited that niche over a few millions of years.

“We became really good at it and way more effective and efficient than other animals, but the innate ability to be bipedal is something that many animals, and all primates, have.”