Baboons often travel in structured line formations known as 'progressions' when moving through their home range. Previous studies offered conflicting explanations for this behavior, suggesting it was either random or a strategic positioning to protect vulnerable individuals.
Researchers from Swansea University have re-examined this behavior using high-resolution GPS tracking on a group of wild chacma baboons (Papio ursinus) on South Africa’s Cape Peninsula. Their findings, published in the journal Behavioral Ecology, indicate that baboon movement patterns are influenced by social bonds rather than survival strategies.
The team analyzed 78 travel progressions over 36 days and found that the order in which individual baboons traveled was not random. They tested four potential explanations for the progression order: protecting the vulnerable, competing for resources, following leaders, and patterns emerging from social relationships.
After analyzing the data, researchers concluded that the baboons' movement patterns were driven solely by their social relationships. Dr. Andrew King, Associate Professor at Swansea University said: “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. Instead, it’s driven by who they’re socially bonded with. They simply move with their friends, and this produces a consistent order."
Dr. King further explained: “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. 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.”
This finding introduces a concept known as a ‘social spandrel’. In buildings, spandrels are triangular spaces that emerge as by-products when arches are placed side by side. In biology, a spandrel refers to a trait arising not because it was directly selected for but as a side effect of something else. In this case, consistent travel patterns among baboons emerge naturally from their social affiliations rather than an evolved strategy for safety or success.