Children in the Mbendjele BaYaka society: diet, foraging, and acquisition of skills and botanical knowledge

A research report by Prof. Dr. Karline R. L. Janmaat (Instituut voor Biodiversiteit en Ecosysteem Dynamica, Universiteit van Amsterdam) on master thesis work carried out by Jorin Veen in 2019-2020.

Modern hunter gatherers need a wide variety of skills and knowledge to collect and consume the available resources. It has been hypothesized that the extended juvenile period in humans has enabled us to acquire these skills and knowledge. To study this, we focused on Mbendjele foragers in the northern part of the Republic of Congo. They live in semi-nomadic egalitarian societies, where food items are widely shared on demand. The children are known to start foraging independently from a young age, offering a unique opportunity to study their diet, foraging behaviour, and acquisition of skills and knowledge.

Research team on way to the forest. On a boat on the beautiful Motaba river together with – from left to right – prof. dr. Karline R.L. Janmaat, Moise Dzabatou, Bryndan O.C.M. van Pinxteren, and Merveille Dzabatou.

            Before data collection, the informed oral consent of the children, together with that of their parent(s) and/or caretaker(s), was obtained. In total, 27 children were accompanied during their foraging trips over a rainy period of six months in 2016 (March – August) and during a dry period of five months in 2019 – 2020 (November – March). The data were collected using a combination of a GPS and a voice recorder. In addition, the botanical knowledge of 17 children was tested using pictures of several parts (fruit/seed, leaf, trunk, bark) of foraging-related plant species known to produce edible fruits or seeds.

Flowers as hair decorations. After a full day of collecting fish, some of the girls decided to decorate their, mine, and Bryndan’s hair with flowers.

            It was found that the children spent most time collecting and eating fruits and tubers, with other food items such as caterpillars and honey being highly seasonal. Interestingly, the results indicated that boys spent more time collecting fruits (and honey) whereas girls spent more time collecting tubers (and fish). This resembles a sexual division in foraging behaviour previously observed in adults. Since sharing is a key value in this society, equal proportions of fruits and tubers were eaten by both boys and girls. Finally, the botanical knowledge of the children improved with increasing age, indicating a learning curve of the different foraging-related plant species during childhood.

            These results will, hopefully, provide new insights in the diet and foraging behaviour of modern hunter-gatherers and their acquisition of foraging-related skills and knowledge. In addition, I hope that it will contribute to the protection of the unique lifestyle of the Mbendjele themselves. Almost, if not all, Mbendjele are currently residing in logging concessions. This will most definitely reduce the available wild resources, which probably explains that more than half of their contemporary diet consists of agricultural foods.            

Specifically, I would like to thank my supervisor Prof. Karline Janmaat and Bryndan van Pinxteren for their major contributions, and Haneul Jang and Vidrige Kandza for data collected in 2016. Additionally, I would like to thank Moise Dzabatou and his daughter Merveille Dzabatou for local help with transport and translations. Also, the University of Amsterdam, Max Planck Institute, and the Institut de Recherche en Sciences Exactes et Naturelles (IRSEN) have contributed. Eternal gratitude goes towards the Mbendjele themselves, for welcoming me in their camp, letting me learn their language and participate in their highly valued dance and music activities. Finally, I would like to thank Treub Maatschappij for enabling this research and valuable personal experience. Like the Mbendjele would say: Esengo ike!

Disclaimer: Informed oral consent was obtained of the children and their parent(s)/caretaker(s), both for participation in the research and the use of their pictures. For further use of the pictures, permission has to be asked to Prof. Karline Janmaat and Jorin Veen.

Lisa Becking receives prestigious VIDI scholarship

Treub-Mij member Lisa Becking has received a prestigious personal VIDI grant from the Dutch Research Council (NWO). She will be able to continue her work on tropical marine lakes by consolidating her appointment at Wageningen University and Research and strengthening her own research group. Lisa was already a member of the Young Academy.

We would like to congratulate Lisa with this impressive accomplishment!

Reconstructing the Eocene to Oligocene history of Sapotaceae in Myanmar

A research report by Daniel Perez-Pinedo (Instituut voor Biodiversiteit en Ecosysteem Dynamica, Universiteit van Amsterdam). The resulting masters thesis has been awarded the East-West Seed Graduation Prize for Plant Sciences 2020 of the The Royal Holland Society of Sciences and Humanities.


The Eocene–Oligocene Transition (EOT) (~33.9Ma) is characterized by climate cooling and paleogeographic change and constitutes one of the most remarkable time intervals in the Cenozoic. This climate transition had a major impact on SE Asia, one of the most biodiverse areas and tectonic active regions in the world. However, terrestrial vegetation response in SE Asia across the EOT transition remains poorly understood.

The Cenozoic vegetation dynamics of Myanmar have been scarcely documented, yet are of great interest to unravel paleogeographic and paleoclimatic history. The family Sapotaceae is of particular concern since it has been a dominant component of SE Asian megathermal lowland wet forests ever since the early Eocene. However, their genera delimitation, origins, and direction of evolutionary change across the EOT remain uncertain. The Central Myanmar Basin (CMB; Myanmar) holds a sedimentary record ranging from upper Eocene – lower Oligocene, which is subdivided into the Yaw and Shwezetaw formations respectively. This sedimentary record presents an excellent opportunity to study the development of the SE Asian forests across the EOT.


In this project I joined the Myanmar Paleoclimate and Geodynamics Research group which focuses on geodynamic, tectonic, paleoclimatic, and paleoenvironmental studies of the Burmese sedimentary archives over the last 120 Ma. The last MyaPGR expedition took place in January 2020. It was led by Dr. Alexis Licht and consisted of Dr. Pierrick Roperch and PhD candidate Jan Westerweel (both from Université de Rennes), Dr. Amy Gough (Royal Holloway, University of London), and myself (Universiteit van Amsterdam). The main goal of the expedition was to report changes in palyno-assemblages across the EOT revealed by the main pollen markers.

The expedition operated in the south of the CMB located at the southern edge of the eastern Himalayan orogen and the Indochinese margin (Figure 1). We traveled to the Minbu sub-basin and visited 6 geological sections of scientific interest where we sampled for pollen, biological markers, fossil wood, amber, and also collected samples in order to conduct paleomagnetic dating (Figure 2). In particular we focused on the Yaw and the Shwezettaw formations, ranging from the late Eocene to the Early Oligocene respectively.

Figure 1: Map of Myanmar and background elevation and sampling area in the Minbu sub-basin

Figure 2: The expedition team observing an outcrop where geological strata of Paleogene age are exposed (Myanmar). Photo credits: Amy Gough

The analysis

The samples were processed at the University of Amsterdam and pollen were examined under light microscopy (LM) and scanning electron microscopy (SEM). The palynological data were analyzed with a cluster analysis tool CONISS that is based on a broken stick model. We also applied ordination multivariate analysis such as Detrended correspondence analysis (DCA) and non-metric multidimensional scaling (NMDS). We observed differential palyno-assemblages resembling changing vegetation across the tropical Eocene into the cooler Oligocene. We also reported different depositional environments across the transition. We interpreted these changing trends to be derived from potential global cooling, increased aridity, and the progressive uplift of the Indo-Burman Ranges (IBR). The EOT reveals itself as one of the main drivers of paleoenvironmental dynamics leading to a pronounced terrestrial reorganization within terrestrial vegetation related to climatic and biogeographic dynamics in Myanmar, possibly extensive to SE Asia.


Having had the opportunity of going to the tropics to conduct fieldwork has resulted in a greater personal engagement in the project as well as a better understanding of the topic. I acquired a better grounded in situ understanding of both the ecological context (vegetation, forest composition) and the geological context regarding lithology and sedimentology of the outcrops of our interest in the Minbu sub-basin. Finally, having had the opportunity of working as a junior member of a well-structured professional research team which consisted of both international and Burmese researchers was both enriching and professionally and culturally challenging.

Nieuw-Guinea het eiland met de meeste plantensoorten ter wereld

Nieuw-Guinea is het grootste tropische eiland in de wereld en herbergt veel, tot nu toe nog intacte ecologische gradiënten – van mangroven tot tropische alpiene graslanden. Dat is ongeëvenaard in de Aziatisch-Pacifische regio. Er is nooit een poging gedaan om het volledig aantal soorten vaatplanten van Nieuw-Guinea kritisch te catalogiseren. Tot nu toe. 

In Nature is de eerste en enige door experts geverifieerde checklist van de vaatplanten van Nieuw-Guinea en de omliggende eilanden gepubliceerd. De openbaar beschikbare checklist bevat 13.634 soorten (68% endemisch), 1.742 geslachten en 264 families – wat suggereert dat Nieuw-Guinea floristisch het meest diverse eiland ter wereld is. Peter van Welzen: Vakkennis bleek essentieel voor het samenstellen van checklists in het digitale tijdperk: alleen vertrouwen op online taxonomische bestanden zou het aantal soorten met 22% hebben doen toenemen. Rodrigo Cámara: Het ontdekken van nieuwe soorten vertoont geen tekenen van afvlakking en de onderzoekers bespreken stappen om botanisch onderzoek in de ‘Laatste Grote Onbekende’ te versnellen.

Peter van Welzen: De checklist vergemakkelijkt het determineren van exemplaren. Dit is belangrijk bij verschillende soorten onderzoek, variërend van ecologie tot etnobotanie.