Chimpanzees are tropical primates commonly described as omnivores. In the wild, however, they are specialized fruit-eaters with fruits as their primary food source. Chimpanzees are referred to as frugivores in scientific literature and are classified as frugivorous omnivores.
What our closest relatives eat in the wild – especially their meat and fruit consumption – is crucial for how we understand what our own natural species-specific and biologically appropriate diet looks like! See also here and here. It also matters for primate nutrition in captivity, which is often problematic.
What do chimpanzees eat in the wild?
Wild chimpanzees are specialized fruit-eaters, have adaptations for fruit-eating, and have a frugivorous diet. That means they eat mainly fruits, but also other plant parts, insects and eggs, and sometimes meat.
According to the Jane Goodall Institute, chimpanzees eat figs (around 50% of the diet) and fruits, which comprise the bulk of the diet. Tender leaves from tropical trees are an important part of the diet, too. Additionally, they eat other plant foods like flowers, nuts and seeds, tubers, and even bark. They eat over one hundred types of plant species! Insects make up a few percent of the diet. Animal products (including eggs, insects, and meat) account for around 6% of the chimpanzee diet. Therefore, meat is a small fraction of around 1-2%. Goodall calculated 4,2% insects and 1,4 % meat in the diet of Gombe chimpanzees.
According to the Chimfunshi Wildlife Sanctuary, chimpanzees eat around 3-6 kilos of food and 80 different “food items” daily – basically eating throughout the day.
It is noteworthy that wild fruits (found in tropical climates) consumed by primates have other carbohydrate profiles (higher in fructose and lower in sucrose) and are higher in micronutrients, proteins, and fiber than cultivated fruits (K. Milton, 1999).
All chimpanzee diets are fruit-based, but highly variable
We have to take into account that the diets of chimps are highly variable, depending on ecological conditions and food abundance. Some of the foods of the chimps’ diet are fallback foods, not preferential foods:
“Highly frugivorous primates like chimpanzees (Pan trogolodytes) must contend with temporal variation in food abundance and quality by tracking fruit crops and relying more on alternative foods, some of them fallbacks, when fruit is scarce… Leaves also contributed much of the diet and served as fallbacks when nonfig fruits were scarce.”Watts et al., 2012
Fallback foods: The diet of chimpanzees depends on food availability!
Generally, most animals are forced to adapt their diet depending on food availability. Therefore, most diets of species vary with time and space. Usually, a species has preferred foods but cannot always readily access those foods. This limited availability makes them turn to their “survival foods.” Our fruit-loving primate family – apes and monkeys – turn to seeds, shellfish, meat, nuts, and insects when fruit – their preferred food – is not abundant:
“Across the range of the anthropoids, fruit is the major resource…
…in adapting to local conditions different species will extend that frugivorous preference in any number of directions—seeds and grasses (gelada), leaves (colobines and mountain gorillas), meat (chimpanzees, baboons), shellfish (chacma baboons), nuts (orangs, chimpanzees, uakari), and insects (chimpanzees, capuchins, squirrel monkeys)… Such extensions might be in the direction of either lower quality or higher quality resources. However, the key element is that primates on the whole have a preference for relatively high quality resources.” citation from Craig Britton Stanford, Henry T. Bunn; Meat-Eating and Human Evolution; Oxford University Press, 2001 (p.307-8)
All of this raises some questions:
- What foods are “only” fallback food?
- What foods are optimal/preferred foods?
- What foods are really essential in the chimpanzee diet?
- What about meat in this context? Is meat essential?
How much meat do chimpanzees eat?
Meat from vertebrates accounts for ca. 1-2% of a typical chimpanzees’ diet (see above). However, those numbers vary and fluctuate: some individuals can consume up to 5% or, in rare cases, 10%, while others might not consume vertebrate meat at all (see below).
Not all chimpanzees eat the same amount of meat
We still know little about how much meat chimpanzees consume in the wild. The chimpanzee subtype Bonobo Pan paniscus, which is closest related to humans, are not as well studied as the better-known chimpanzees Pan troglodytes. However, it’s known that bonobos consume less meat than chimpanzees.
Before the discovery of Jane Goodall, the world’s most renowned chimpanzee expert, the primates were considered vegetarian. This fact alone is already a good hint of how rarely they hunt in the wild.
Do chimpanzees need meat?
The role of meat in the chimpanzee diet is still a topic of investigation. It’s often unclear if animals eat a type of food because of an essential nutritional requirement or “only” additional nutritional benefits. Or because there is simply nothing better around.
It is not entirely understood if meat plays an essential or only an additional nutritional role or even primarily a social role in the diet of chimpanzees!
But would frugivores get enough proteins without meat? Most likely, yes!
Is meat a nutritional need in the chimpanzee diet? Hunting and meat-eating vary between wild chimpanzee groups and time. Some individuals seem to consume very little meat – or even no meat at all. On the other hand, the preference for fruit stays the same for all. This is the first clue that meat might not be an essential nutrient source. However, meat might be an additional protein source for males: hunting and meat-eating are primarily done by males and seem to involve social aspects among different male individuals.
Chimpanzees get protein from fruits, greens and nuts
At first glimpse, an obvious explanation for hunting and meat eating in frugivorous animals is to acquire protein-rich foods. While this is a plausible possible cause, let’s not lose sight of the bigger picture: Not all animals need to obtain protein from animal-based foods. For many animal species, meat is not required as a nutrient source!
Moreover, protein-rich foods do not seem to be a priority for chimpanzees, as described by leading primate researchers (summarized here by Takemoto, 2002):
“…chimpanzees preferred food items with high sugar content or caloric intake rate, regardless of protein content”Takemoto, 2002
Greens can make up to 20% of the diet of chimpanzees. However, unlike herbivores, apes are not specialized in eating and digesting cellulose-rich greens. Instead, the apes consume the tender parts of leaves and young leaves. Chimpanzees consume leaves, buds, or young shoots with a preference for young leaves or types of leaves with low tannin content (Takemoto, 2003). Those parts are easier to digest, are a rich source of minerals and amino acids, and can even have a slightly sweet taste. “Young leaves from tropical trees are far more nutritious than I realized. In fact, the young tips have the same profile of essential amino acids as meat, although in lower concentrations,” said Milton.” (source)
Thus, meat-eating might be optional for primates rather than obligatory (nutritionally essential). To put this into the right setting, while fruits are not typically known as a protein source, we must consider that chimpanzees eat wild, tropical fruits – which are much more nutritious than temperate fruits.
Read more about the protein content of a frugivorous diet here.
Males are the meat-eaters…
It seems to remain an open question if meat has some essential nutritional function (meaning that it is a requirement for survival) in the chimp diet.
One valid point against nutritional requirements is that meat consumption is primarily a male thing! It is unclear whether females and juveniles also need to obtain the nutrients provided by meat. “Although both adult males and females and juveniles derive their dietary protein largely from a daily fruit and seasonal nut consumption, our data indicate that some adult males also derive a large amount of dietary protein from hunted meat.” (Fahy et al., 2013). Further, there are purely social aspects to hunting and meat sharing, such as strengthening alliances among different males (Newton-Fisher, 2015). These types of behaviors are hard to prove, as we, unfortunately, cannot know what ultimately is going on in the minds of animals.
Is meat fall-back food?
Another possible explanation is that chimps only eat meat when better foods are unavailable. While this hypothesis was not confirmed, meat-eating might have an additional nutritional benefit. In the case of males, eating more proteins and gaining more muscle mass and strength for masculine dominance comes to mind.
The natural diet of chimpanzees in the wild is highly frugivorous, and meat is a rare food in their diet – not a staple. Meat from smaller vertebrates (like monkeys) might not be necessary for protein intake, as not all individuals eat meat regularly – or at all! Therefore, we can conclude that our closest relatives are frugivores who eat a fruit-based diet with little animal foods – not a typical omnivorous diet!
Besides observing their diet in the wild, there are fascinating anatomical and physiological adaptations that have evolved with high-fruit diets. Learn more here:
- Dani Sarusi, 10 things chimpanzees eat. Jane Goodall (2022) (available at https://janegoodall.ca/our-stories/10-things-chimpanzees-eat/).
- W. C. Foundation, What do chimpanzees eat? WCF | What they eat (available at https://www.wildchimps.org/about-chimpanzees/what-they-eat.html).
- No author (2020) Buy a chimp a meal, Chimfunshi Wildlife Orphanage. Available at: https://chimfunshiwildlife.org/appeal/buy-a-chimp-a-meal/ (Accessed: April 26, 2023).
- What do chimps eat? A chimpanzee’s Diet & eating habits in the Wild African forests. Safari Partner. Available at: https://safaripartner.com/blog/what-do-chimps-eat (Accessed: April 28, 2023).
- K. Milton, Nutritional characteristics of wild primate foods: Do the diets of our closest living relatives have lessons for us? Nutrition. 15, 488–498 (1999), doi:10.1016/s0899-9007(99)00078-7.
- N. E. Newton-Fisher, The diet of chimpanzees in the Budongo Forest Reserve, Uganda. African Journal of Ecology. 37, 344–354 (1999), doi:10.1046/j.1365-2028.1999.00186.x.
- D. P. Watts, K. B. Potts, J.S. Lwanga, J. C. Mitani, Diet of chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda, 2. Temporal Variation and Fallback Foods. American Journal of Primatology. 74, 130–144 (2011), doi:10.1002/ajp.21015.
- Craig Britton Stanford, Henry T. Bunn; Meat-Eating and Human Evolution; Oxford University Press, 2001 (p.307-8)
- A. Sistiaga, R. Wrangham, J. M. Rothman, R. E. Summons, New insights into the evolution of the human diet from faecal biomarker analysis in wild chimpanzee and gorilla faeces. PLOS ONE. 10 (2015), doi:10.1371/journal.pone.0128931.
- No author named, Adult male chimps regularly eat meat, unlike other chimps. PNAS Journal Club / Anthropology (available at https://www.pnas.org/post/journal-club/adult-male-chimps-regularly-eat-meat-unlike-other-chimps).
- H. Takemoto (2002) Phytochemical determination for leaf food choice by wild chimpanzees in Guinea, Bossou. Available at: https://www.greencorridor.info/data/Phytochemical_Determination_for_Leaf_Food_Choice_by_Wild_Chimpanzees_in_Guinea__Bossou.pdf (Accessed: July 23, 2023).
- N.E. Newton-Fisher, The Hunting Behavior and Carnivory of Wild Chimpanzees. W. Henke, I. Tattersall, Handbook of paleoanthropology (Springer Berlin Heidelberg, Berlin, Heidelberg, 2015) (p.1661-91).
- J. Russ, Communication by chimpanzees improves cooperative hunting success. ASU News (2022) (available at https://news.asu.edu/20220729-communication-chimpanzees-improves-cooperative-hunting-success).
- G. E. Fahy, M. Richards, J. Riedel, J.-J. Hublin, C. Boesch, Stable isotope evidence of meat eating and hunting specialization in adult male chimpanzees. Proceedings of the National Academy of Sciences. 110, 5829–5833 (2013), doi:10.1073/pnas.1221991110.