Baboons walk in lines just to stay near their friends

In the wild, group living offers animals many advantages, from protection to shared knowledge. But it also brings complexity. Who goes first? Who follows? And why? For decades, scientists have tried to explain why animals like baboons walk in organized lines called “progressions.”

Some believed it was about defense. Others thought it had to do with food. But a new study from Swansea University reveals a different truth. Baboons, it turns out, may just want to walk with their friends.

This insight emerged from one of the most detailed baboon movement studies to date. The team tracked 13 chacma baboons using high-resolution GPS collars. These baboons lived in the Da Gama Park area of South Africa’s Cape Peninsula.

Over 36 days, the team recorded 78 coordinated group movements. Each one showed the animals lining up in a consistent, non-random way. But instead of a tactical plan, social ties seemed to shape this order.

Testing old baboon movement theories

Previous ideas about baboon movement suggested clear strategies. The “risk hypothesis” argued that strong individuals like males took positions at the front or rear to shield weaker members.

The “competition hypothesis” suggested subordinates moved up front to access food before dominants arrived. And the “decision-making hypothesis” claimed that leaders guided the troop from the front. All these theories aimed to explain baboon lines as evolved survival tools.

But the Swansea team’s results didn’t match those expectations. Their GPS data revealed no strong link between position in the line and safety, food access, or leadership.

Social bonds shape movement

In fact, dominant baboons often appeared in the center rather than the front. Subordinates moved toward the edges, not because of strategy, but due to social positioning.

“Surprisingly, the consistent order we see for the baboons we studied isn’t about avoiding danger like we see in prey animals when they position themselves in the middle of their social group, or for better access to food or water like we see in the movements of plains zebra,” noted Dr. Andrew King, associate professor at Swansea University.

Their movement is guided by social bonds rather than individual choices, creating a consistent pattern.

“In the baboon group we studied, the more socially connected, higher-ranking individuals usually walk in the middle of the group, while lower-ranking baboons are often out in front or at the rear,” Dr. King said.

“During these group movements, like heading to a familiar sleeping spot, it’s likely that the group already knows where they’re going. So, the baboons at the front aren’t really leading; they’re just out ahead.”

How baboon walks reflect friendship

This unexpected discovery led the researchers to apply the concept of a “social spandrel.” In architecture, a spandrel is a space that arises between two arches.

It wasn’t designed on purpose. It just appears as a side effect. In biology, the term refers to traits that emerge not from direct evolutionary pressure, but as by-products of other forces.

In the case of baboons, social relationships were the hidden architects. Friends stayed close together, and these pairs naturally formed repeatable line formations. The travel order was not the result of strategy, but a side effect of close companionship.

Over time, this created what looked like an organized pattern, but it was just friendship in motion.

Stable movement of baboons

To reach these conclusions, the researchers collected 13.87 hours of data using collars fitted to adult baboons. They tracked the animals from morning until evening.

The team defined a progression only when the group moved together in a tight, aligned formation. Progressions happened throughout the day, but many occurred in the late afternoon when baboons returned to their sleeping site.

Interestingly, the baboons’ movement speed, group shape, and order remained stable across different times of day.

Whether they were heading to forage or returning to rest, the travel line followed the same structure. This consistency further ruled out time-sensitive strategies like racing for food or responding to risk.

Friends shape movement

The researchers compared how close baboons stayed to each other during progressions and during casual group activity.

The same pairs that spent time together while resting also stuck close while walking. Dominant baboons were more central in the group, not because they pushed others aside, but because others naturally gathered near them.

This pattern suggests a kind of social gravity. Baboons with stronger social bonds pull others toward them. Dominant individuals had more neighbors, but their neighbors changed often.

Subordinates had fewer companions, which often left them at the edges. Over time, these patterns led to consistent line positions.

No strategy, just bonds

The data showed no link between position and benefits like food or safety. Even near risky urban areas, the order stayed the same.

This questions the idea of baboon lines as tactical formations. Instead, movement reflected social bonds.

If strategy mattered, dominant baboons might lead or guard the rear. But they stayed central. These results suggest social ties, not tactics, shape group travel.

Baboons walk in familiar lines

“We know that strong social bonds are important for baboons – they’re linked to longer lives and greater reproductive success,” said Marco Fele, the study’s lead author and PhD student at Swansea University.

“But in this context, those bonds aren’t serving a specific purpose. The travel order we see is simply a by-product of those relationships, not a strategy with immediate benefits. Our study highlights the potential for these kinds of spandrels in collective animal behavior.”

This view encourages scientists to rethink wild behavior. Not all group actions are strategic or useful. Sometimes, they reflect social bonds. In baboons, these ties shape both grooming and walking order.

In the end, this study reminds us that friendship may be one of nature’s most powerful organizing forces. Even in the wilderness, when it comes to walking through life, we often choose to do it side by side with those we know best.

The study is published in the journal Behavioral Ecology.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–