Striking similarities in how humans and other primates search for food
How unique is the human capacity for learning and adapting to an environment? In field research – in the rainforest and Artis Zoo – primatologist Karline Janmaat is studying how humans and other primates adapt to their environment in their search for food. She will give her inaugural lecture as Professor of Cognitive Behavioural Ecology on 10 June.
We don’t yet know enough about the similarities and differences between the intellectual capacities of animal species, says Janmaat. ‘By researching which primate species possess which capacities, we can discover at which points in time they evolved.’ Janmaat is researching how humans and other primates use their knowledge to find and gather food. She spent 20 years observing humans and other primates in their daily search for edible fruit in the rainforests of Indonesia, Ivory Coast, Uganda and the Republic of Congo. She followed the Bayaka, a group of pygmies who live as hunter-gatherers, and a group of chimpanzees that grew up in the same kind of rainforest.
Primatologist Karline Janmaat is Endowed Professor of Cognitive Behavioural Ecology, a joint chair at Leiden University and Artis Zoo (in Dutch). Her research focuses on the development and evolution of intelligent behaviour, and the cognitive function of humans and animals.
Exceptional navigation skills
Janmaat discovered several similarities: the Bayaka and the chimpanzees both proved to possess exceptional navigation skills and be able to find their way over long distances. They both use a network of paths. The research also showed that chimpanzees remember their experiences in food trees for years and plan their routes to be ahead of their competitors.
‘Gorillas we haven’t seen using tools in the wild are using twigs to pick peanut butter out of a termite mound in Artis.’
Research at Artis Zoo
In her inaugural lecture Janmaat points to another environment that could be used more often: zoos. Since Artis opened in 1838, scientific research has always had a fundamental role there. This endowed chair is currently facilitating various studies of primate species that cooperate voluntarily. Janmaat is testing the ability of mandrills to learn time intervals, for example. Part of their food is buried and the research team then looks at the extent to which the mandrills develop patterns in their search behaviour. Similar research is now being conducted with the gorillas and red-ruffed lemurs (Strepsirrhini) at Artis.
The studies may reveal how the environment influences the development of cognitive abilities. ‘A number of behaviours in zoo animals really fascinate field primatologists,’ says Janmaat. ‘Gorillas that we’ve never seen using tools in the wild are using twigs to pick peanut butter out of a replica termite mound in Artis.’ Janmaat and her team will soon be starting a new study into irrational decisions in chimpanzees and humans. What information do they use when looking for fruit? Virtual fruit in this case. They will search on a touch screen for virtual fruit in a digital rainforest.
This study could contribute to programmes returning monkeys to their natural habitat, should this ever be necessary. Janmaat is using the data from the chimpanzees that still live in the rainforest. She emphasises that this knowledge must not be lost. ‘The rainforest is disappearing at a rapid rate. We may be the last generation of researchers who can still generate this insight and gain a better idea of our evolutionary history.’
Photo above article: Ronald van Weeren
Text: Linda van Putten