For most of the twentieth century, the textbook baboon was a bully. Savannah troops were described as pyramids of aggressive males, with rank settled by size and canine length, and everything else in the group’s life following from that. Half a century of continuous field observation in Kenya has largely dismantled that picture, and the researcher most responsible for dismantling it is Shirley Strum.
Strum is an emerita professor of anthropology at UC San Diego and director of the Uaso Ngiro Baboon Project. She began studying olive baboons in Kenya in 1972, as a graduate student, and has followed the same population and its descendants ever since. In a 2023 account of her career in the journal Primates, she described the work as fifty years of watching wild Papio anubis and revising, repeatedly, what she thought she was looking at.
The model she went to Kenya to test
Strum did not arrive as a sceptic. She went to test what was then called the baboon model: the mid-century idea that early humans leaving the forest for the savannah would have resembled large, aggressive male baboons, and that studying baboons could therefore stand in for studying human origins. Speaking to Marc Bekoff for Psychology Today in October 2025, she explained that she had originally set out to understand where human aggression came from.
The methodology of the field at the time helped produce the answer the field expected. Observers identified large adult males as individuals. Females and juveniles were largely treated as background. A study design that only tracks the biggest animals will tend to return a story about the biggest animals.
Strum began identifying every animal in her study troop, males and females, adults and infants, and following them across years rather than seasons. Once the females had names and histories, the story changed.
What fifty years of watching actually showed
Females, she found, were the stable core. Males transferred between troops; females stayed, remembered, and maintained the relationships that held the group together. Aggression existed, but it was costly and risky, and the males who relied on it tended to do worse over time than long-resident males who invested in what Strum calls friendship.
What she documented instead of brute hierarchy were long sequences of negotiation. A male grooming a female for weeks before she came into oestrus. A female tolerating a subadult male near her infant, then benefiting from his support months later. Support, tolerance and access tracked earlier social investment more closely than they tracked size. UC San Diego’s department summary of her work puts the significance plainly: she was the first to uncover this level of primate social complexity, which helped build the wider case that animals have minds and not merely brains.
In her framing, friendship precedes strategy. A favour cannot be cashed in with an animal who does not trust you, and trust takes a long time to build.
A favour economy, with limits
“Favour economy” is a human gloss on something baboons do without any of the machinery humans use to keep score. There are no tallies, no promises, no language. What there is, on the available field evidence, is recognition of specific individuals and a strong tendency to direct grooming, tolerance and coalition support toward animals who have offered the same in the past.
Strum is careful about the ceiling of the comparison. In a 2012 paper in the American Journal of Physical Anthropology titled “Darwin’s monkey: why baboons can’t become human,” she argued that baboons cannot break through a social complexity ceiling that humans have broken, because they lack symbols, language, culture and the forms of cooperation those tools make possible. Whatever the exchange economy is, it runs on recognition and habit rather than contract.
That distinction matters. It is tempting, reading about a baboon repaying support with support, to slide into the language of debt and repayment. The behaviour is observable. The internal accounting, if there is any, is not something a field observation can reach.
Where the reciprocity idea actually came from
Strum’s contribution is often misdescribed, including in popular retellings of her work. She is not the origin point for the claim that baboons trade favours. That attribution belongs to Craig Packer, whose 1977 paper in Nature reported that coalition formation among male olive baboons met the criteria for reciprocal altruism, testing a framework Robert Trivers had proposed in 1971.
What Strum’s long-term record supplies is different and, arguably, harder to get: not a single demonstration that reciprocity exists, but decades of evidence that olive baboon society is organised around it. That females anchor the relationships. That social investment outperforms aggression across a lifetime. That individuals track who has helped them, and act on it years later. A single striking observation can suggest a mechanism. Only a fifty-year dataset can show it is the ordinary way the society runs.
The pattern also shows up in decidedly unromantic contexts. When her main study group fissioned in 1981, the daughter troop was made up of young male crop raiders and the females who associated with them. The social bonds that made cooperation possible also carried a risky foraging strategy through the group. Favour economies, if that is what they are, do not only produce protection. They also produce trouble.
Why the framing has consequences
Strum’s work has always sat at the edge of a policy problem. Olive baboons are intelligent, adaptable, and increasingly in conflict with the humans whose farms and homes now cover much of their historic range. In a December 2025 piece for The Conversation, she argued that the problem is not baboon malice but human behaviour, and that the conflict will not change unless human attitudes and practices change first. Baboons raid because human food is calorie-dense and easy to digest, which is a rational answer to the question of nutrition per unit of effort.
How people think about baboon minds shapes how they respond. A troop understood as a mob of aggressive males invites one kind of policy. A troop understood as a network of long-term relationships, with memory and negotiation, invites another.
Strum’s answer is coexistence through compromise, which she frames as converting a win-lose into a win-win. Neither side gets everything. It is not a sentimental position. It is the conclusion of someone who has watched the same animals for half a century and seen what happens when the alternative is tried.
Where the resemblance ends
The interesting question was never whether baboons are like us. It is where the likeness stops. Strum’s answer, after fifty years, is that baboons have agency, strategy and something recognisable as friendship, but not the symbolic scaffolding that lets humans build cathedrals, contracts, or crop-protection policies.
Whatever the baboons are running, it runs on faces and history rather than words. It does need time, and it needs an observer willing to stay long enough to see the second half of the exchange. Strum stayed. Her study population is still being followed, and on her account the baboons are still negotiating.