The evolution, ecology and conservation of honeyguide-human mutualism
This project focusses on a unique mutualism: the foraging partnership between the Greater Honeyguide Indicator indicator and human honey-hunters whom it guides to bees’ nests. Honeyguides know where bees’ nests are located and like to eat beeswax; humans know how to subdue the bees using fire, and open nests using axes. By working together, the two species can overcome the bees’ defences, with benefits to both. Remarkably, this relationship has evolved through natural selection, rather than through training or domestication which underpins cooperation by other human foraging partners such as dogs or falcons. The honeyguide-human system provides a wonderful opportunity to study the ecology and evolution of mutualisms in nature, because local human and honeyguide populations vary strikingly in whether and how they interact, and because we can readily manipulate these interactions experimentally.
Claire Spottiswoode and her team have been studying human-honeyguide interactions since 2013 in the Niassa National Reserve of northern Mozambique, collaborating with the honey-hunting community of Mbamba village, and receiving crucial support from the Mariri Environmental Centre led by Keith Begg and Dr Colleen Begg of the Niassa Carnivore Project. A key focus so far has been investigating reciprocal communication between the two parties: not only do honeyguide signal to humans, but in many different cultures humans signal back to honeyguides, giving special calls to attract honeyguides and maintain their attention while following them. Among the Yao honey-hunters of northern Mozambique, this call is a loud trill followed by a grunt: “brrrr-hm!”. In 2016, using a field experiment, we showed that honeyguides were twice as likely to initiate a cooperative interaction with humans who made this sound compared to humans giving control human and animal sounds, and three times as likely to successfully lead such humans to honey. So honeyguides use these specialised signals to choose partners who are likely to be good collaborators, in a two-way conversation between our own species and a wild animal, from which both partners benefit.
Supported by a Consolidator Grant from the European Research Council, we are now asking whether learning is involved in maintaining a geographical mosaic of honeyguide adaptation to local human cultures; how such reciprocal communication between humans and honeyguides mediates their interactions; what the effects of cultural co-extinctions may be on each partner and their ecosystems; and ultimately, we hope, how quickly such cultures can be re-ignited following their loss. In so doing we hope to test for the first time the hypothesis that reciprocal learning can give rise to matching cultural traits between interacting species. Understanding the role of such phenotypic plasticity is crucial to explain how and why the outcome of species interactions varies in space and time, and to predict how they will respond to a rapidly changing world.
Our main objectives in 2017 were twofold. First, we carried out further experimental work to test the hypothesis that honeyguides learn the signals of their local human cultures, in collaboration with Dr Brian Wood from the University of California Los Angeles and the Max Planck Institute of Evolutionary Anthropology. We did so by working both with Yao honey-hunters at Niassa with whom we’ve collaborated for several years, and with Hadza hunter-gatherers of Tanzania who are also expert honey-hunters and also use a specialized (but different) sound to signal to honeyguides that they wish to cooperate. We received a grant from the National Geographical Society to expand this work further.
Second, we developed a customized app to allow honey-hunters in Mozambique to collect data on their activities, and trained 18 honey-hunters from Mbamba Village to use it. The app runs on rugged handheld Android devices, and enables users with any degree of literacy to collect accurate data on their interactions with honeyguides. This has been working very well, thanks to the enthusiastic support of the honey-gatherers and traditional chiefs of Mbamba Village, the Mariri Environmental Centre, and our data manager, Orlando Ncuela. The app was developed thanks to the expertise of software developers HabitatInfo. David Lloyd-Jones, who will begin PhD studies at the Fitz in 2018, was pivotal in training our initial cohort of honey-hunter collaborators to use the app. Their data will allow us to address a wide range of research questions concerning the ecology, evolution and ecosystem effects of this fascinating human-animal interaction. We are especially happy that this project is allowing us to directly involve Niassa’s community in our data collection, providing them with additional sources of income as well as allowing us to cooperate in scientific research.
Activities in 2017
- In July, Claire Spottiswoode and Brian Wood carried out fieldwork on the honeyguide-human relationship with the Hadza people of northern Tanzania.
- From May to October, David Lloyd-Jones and Claire trained 18 honey-hunters to collect data on their activities with a custom app.
- During September and October, James St Clair, David and Claire captured and colour-marked honeyguides in two core study sites within our Mozambican study area, to establish a marked population for future experimental work.
- With the support of the Mariri Environmental Centre; the 18 honey-hunters are now successfully using the custom app to collect high-quality data on an ongoing basis.
Impact of the project
We hope this study will further our understanding of how mutualisms evolve, and specifically how learnt traits mediating mutualisms may coevolve with one another. Understanding mutualisms is broadly relevant because they help to shed light on the mechanisms that can maintain cooperation among unrelated individuals, and because they have wide reach in ecological communities. The honeyguide-human mutualism has already died out from large parts of Africa, as the continent develops; it would be a tragedy if it vanished altogether before we fully understood this part of our own evolutionary history.
European Research Council; National Geographic Society; Max Planck Institute for Evolutionary Anthropology.
Prof. Claire Spottiswoode (FIAO, UCT and, U. Cambridge)
Dr Colleen Begg (Niassa Carnivore Project)
Keith Begg (Niassa Carnivore Project)
David Lloyd-Jones (FIAO, UCT)
Orlando Ncuela (Niassa Carnivore Project)
Dr James St Clair (U. Cambridge)
Dr Brian Wood (U. California Los Angeles and Max Planck Institute)