Nav: Home

Competent chimpanzee nutcrackers

February 06, 2019

Humans consider themselves as the tool user per excellence, and all known populations use them on a daily basis, although to different degrees. Previous work comparing human tool use skills to those of other species tended to place the animals in artificial conditions, removed from their natural environment. Such comparisons disadvantage the animals and are prone to underestimating the technological skills demonstrated by wild populations. In a first comparison between individuals of two groups of humans and chimpanzees, both cracking nuts naturally in their environment, we could test how quickly and how completely the technique was acquired by apprentices of the two species. The Taï chimpanzees, in Côte d'Ivoire, famous for their nut-cracking behavior, were compared to the Mbendjele BaYaka people who also habitually crack the same species of nuts, Panda oleosa, in the forest of the Republic of Congo. Following Mbendjele women groups as they forage in the forest, we used the same measures of efficiencies as used previously on the Taï chimpanzees to follow how the technique is acquired by both in the forest.

In a previous study that was published in 2017 Boesch and his colleagues compared the efficiencies of the adult females in both species, revealing surprising similarities in the performances of the two populations, despite the use of different tools, i.e. the humans using sharp-cutting metal hammers and the chimpanzees stone hammers. In the present study, the "apprentices" of both species acquired the technique initially slowly, with similar kinds of mistakes, such as hitting the anvil directly with the nut, or placing the nut on the ground instead on the anvil, and both require years of practice to become experts. Christophe Boesch, director at the Max Planck Institute for Evolutionary Anthropology and lead author, said: "This study is the first to compare humans and chimpanzees performing the same technique in the forest, thereby ensuring that the two species possess the same level of prior experience with the tools used, the nuts, as well as the potential of observing experts pounding the nuts. In both species, prior experience is key to the acquisition of technical skills."

However, even after correcting for differences in speed of maturation between the two species, chimpanzees acquired the technique more rapidly and reached adult efficiency earlier than humans. "Obviously, the Mbendjele people solve a lot more complex technical skills on a daily basis in the Congo forest, but it is intriguing to see that in one technical challenge, the technical skills are acquired more rapidly in chimpanzees than in humans. Nuts constitute an important part of the diet for many months each year in chimpanzees, while they may play a lesser role for humans, and so this could illustrate the power of the environment as a selective pressure for learning skills", concluded Boesch.

Furthermore, teaching, which has regularly been proposed to be a unique human ability, was observed regularly in both species between experts and apprentices learning the technique. Nut-cracking is a relatively complex technique employing three distinct objects, the nut, the anvil and the hammer, that need to be arranged and used in a particular way to open the nuts without smashing them. The frequency of the teaching interactions observed in both species supports the idea that teaching facilitates the acquisition of a technique and should therefore be more frequent for complex behaviors in both species.

The relatively similar level of teaching interactions in the two species and the more rapid acquisition of nut-cracking proficiency in chimpanzees come as a surprise given the assumption that humans are generally superior in tool-using skills. The authors stress that both chimpanzees and humans need to adapt to the challenge they face daily in the environment, and the more similar those are, the more similar the solutions and cognitive skills both species will develop. Similar natural comparisons in the future will add to the much-needed comparative assessment of the technical skills of the two species and allow assessment of how humans may truly differ in tool use.
-end-
Original publication:

Christophe Boesch, Dasa Bombjakoca, Amelia Meier & Roger Mundry
Learning curves and teaching when acquiring nut-cracking in humans and chimpanzees
Scientific Reports, 06. Februar 2019

Contact:

Prof. Dr. Christophe Boesch
Max-Planck-Institut für evolutionäre Anthropologie, Leipzig
+49 341 3550-200
boesch@eva.mpg.de

Max Planck Institute for Evolutionary Anthropology

Related Chimpanzees Articles:

How humans and chimpanzees travel towards a goal in rainforests
How do human-unique ranging styles, like large home range and trail use, influence the way we travel to our goals?
Chimpanzees' working memory similar to ours
Working memory is central to our mental lives; we use it to add up the cost of our shopping or to remember the beginning of this sentence at its end.
Research identifies key driver for infanticide among chimpanzees
Study concludes that the sexual selection hypothesis was the main reason for the high rates of infanticide among a community of chimpanzees in Uganda.
Chimpanzees catch and eat crabs
Chimpanzees have a mainly vegetarian diet, but do occasionally eat meat.
Chimpanzees at the crossroads: adapt to living outside protected areas
Chimpanzees at the crossroads: how they adapt to living outside protected areas Research carried out into the impact of changes to chimpanzee habitats found they have adapted to human developments in a number of ways -- including learning how to cross roads safely and the best times to visit human habitats -- but their survival is still threatened.
Social insecurity also stresses chimpanzees
Researchers from the Max Planck Institute for Evolutionary Anthropology conducted behavioral observations and collected urine samples for cortisol analysis of male chimpanzees of the Tai National Park, Ivory Coast, during periods of intense male-male competition.
Sweeping census provides new population estimate for western chimpanzees
A sweeping new census published in the journal Environmental Research Letters estimates 52,800 western chimpanzees (Pan troglodytes verus) live in eight countries in western Africa, with most of them found outside of protected areas, some of which are threatened by intense development pressures.
Chimpanzees lose their behavioral and cultural diversity
Chimpanzees are well known for their extraordinary diversity of behaviors, with some behaviors also exhibiting cultural variation.
Human impacts erode behavioral diversity in chimpanzees
Much of the variation in the behavior among wild chimpanzee groups may be akin to 'cultural' variation in humans.
Chimpanzees react faster to cooperate than make selfish choices
When it comes to cooperation, there's no monkey business in how some chimpanzees respond.
More Chimpanzees News and Chimpanzees Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab