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Baboons as a model for human evolution

Review article on baboon research published
Guinea baboons (Papio papio) at the DPZ field station Simenti in Senegal. Photo: Julia Fischer
Distribution of the six Papio species Fischer et al. 2017. Image: eLife 8:e50989, https://doi.org/10.7554/eLife.50989.003
Distribution of the six Papio species Fischer et al. 2017 (https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.23144). Species distributions are modified from Zinner et al. 2013 (https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.22185). Male baboon drawings by Stephen Nash. Image: eLife 8:e50989, https://doi.org/10.7554/eLife.50989.003
Prof. Julia Fischer is head of the Cognitive Ethology Laboratory at the DPZ. Photo: Karin Tilch
Prof. Julia Fischer is head of the Cognitive Ethology Laboratory at the DPZ. Photo: Karin Tilch
Illustration of key traits across baboon species. Image: eLife 8:e50989, https://doi.org/10.7554/eLife.50989.004
Illustration of key traits across baboon species. (A) Phenotypic variation between species. Pictures show adukt males and females. (B) Crania of male baboons. (C) Sexual swellings of female baboon during peak estrus. Species are grouped by social organization (uni- and multi-level) and dispersal behavior (male- or female dispersal). Images from Alexis Amann, Andrea Cardini, Sarah Elton, Julia Fischer, Courtney Fitzpatrick, James Higham, Megan Petersdorf, Joan Silk and Larissa Swedell. Image: eLife 8:e50989, https://doi.org/10.7554/eLife.50989.004

Baboons are widespread in Africa. The six species that exist today have spread from the south over almost the entire continent. In the course of evolution, baboons have developed great ecological flexibility and a wide range of social systems compared to other primate species. This makes them an important model for researchers to study complex evolutionary processes. Long-term studies provide additional insights into the relationship between sociality, health, longevity and reproduction. Since the baboons developed at about the same time and in the same habitat as humans, the studies also allow conclusions about the evolutionary history of early human species.

Over the past decades, a number of international primatologists have investigated the way of life, social organization and evolutionary development of various baboon species. Scientists from the Cognitive Ethology Laboratory at the DPZ have also been observing Guinea baboons at the DPZ research station in Senegal for over ten years. Their findings have now been published in a review article of the online journal eLife together with further data on the genus of baboons.

“Long-term studies on different species in different places have provided us with comprehensive insights into the systematics, morphology, ecology, social systems, health and protection status of animals,” says Julia Fischer, head of the Cognitive Ethology Laboratory and first author of the article. “The aim of the article was to summarize the current state of knowledge on the developmental history and lifestyle of baboons and at the same time to formulate outstanding research questions.”

Important findings of the past decades were, for example, that the six baboon species differ not only in morphology and way of life, but also in their evolutionary history. Based on genome analyses of various species, the researchers were able to understand that the initial evolutionary divergence separated a southern lineage that ultimately produced Kinda, chacma and yellow baboons, from a northern lineage that produced olive, hamadryas and Guinea baboons. In addition to the divergence of lines in the course of evolution, the researchers were also able to detect hybridizations and the associated gene exchange between the species.

The behavior and social organization of the baboon species is also diverse. Chacma, Kinda, olive and yellow baboons live in uni-level social systems, which are characterized by male dispersal and a stable core of females. The males' relationships are more characterized by competition for females and aggressive behavior. Between females and males, clear rank hierarchies can be discerned.

Hamadryas and Guinea baboons, on the other hand, live in multi-level social systems. The females change between the groups. Hamadryas baboons establish “one male units”, in which an alpha-male lives with several females, who mate only with it. Several of these “harem-groups” can join together to so-called clans, several clans form bands. The male-male as well as the male-female-relationships are rather characterized by competition and submission. Male Guinea baboons, on the other hand, form close friendships among themselves, aggression can hardly be observed. Female tenure with a given male is voluntarily and may vary between weeks or even years. Guinea baboons also live in small units with one male and up to six associated females. Several units form parties, several parties form gangs.

“Research into the history of baboons and their life in complex societies gives us a better understanding of our own social evolution,” Julia Fischer sums up. “In future studies, we want to investigate further questions, such as the long-term effects of environmental changes such as climate change on social organization, or whether the genetic architecture of baboons influences behavior and flexibility within social systems.”

Review article

Fischer J et al. (2019): The Natural History of Model Organisms: Insights into the evolution of social systems and species from baboon studies. eLife 8:e50989 doi: 10.7554/eLife.50989