Apes eating bananas are cute and typical, but chimpanzees that chomp on crabs are too unusual. Today, researchers at the Department of Anthropology from the University of Zurich revealed for the first time that chimpanzees could eat crabs. The research finding aims to widen “our understanding of why aquatic fauna became more and more important as a source of nutrition in the course of human evolution.”
Researchers from Kyoto University observed how wild chimpanzees caught and preyed on fresh-water crabs in a rainforest in the Nimba Mountains in Guinea year-round. The finding somehow contradicts the common idea that anthropoid apes such as chimpanzees and gorillas, the closest species to humans do not eat aquatic animals.
A copy of the research findings was published Wednesday in an online website of the Journal of Human Evolution. The study reveals the first evidence which proves that non-human apes usually catch and eat aquatic fauna, said Kathelijne Koops, one of the researchers.
In the small and shallow rivers of the rainforest, the chimpanzees haunt for the crabs by scratching and beating up the riverbed with their fingers.
The said study began in 2012 when the team observed how chimpanzees ate river crabs at a water hole in the forests of Guinea in West Africa. To prove that such behavior of chimpanzees happened, the team set up camera traps at four water holes between 2012 and 2014 — this documented and recorded chimpanzees that eat crabs for almost 181 times.
The research team also discovered that these chimpanzees living in the rain forest in the Nimba Mountains of Guinea consumed freshwater crabs year-round. This means that non-human apes regularly catch and choose aquatic fauna as a source of food to survive.
Chimpanzees do eat crabs even though fruits are available. They searched for it in shallow streams in the mountainous rain forest region through either scratching or digging up the riverbed with their fingers. It is in the riverbed where these crabs were mostly found with high nutritional value.
Researchers explained that on rainy season, more river crabs appear on the area. Although, much to their surprise, researchers emphasized that there was no correlation between crab-fishing activity and the amount of monthly rainfall. Chimpanzees like to eat crabs regardless whether it’s rainy or dry season; where there’s not enough water in the streams where crabs can survive.
However, some curious scholars from another institute questioned whether these chimpanzees only rely on river crabs for primary food. Researchers at the Department of Anthropology emphasized, as a result of almost two years of observation, that chimpanzees eat more crabs when there are only a few ants available to munch. This means that aside from river crabs, chimpanzees also like to eat ants. Another possible explanation is that Chimpanzees like to eat crabs and ants because both contain the same nutritional value.
Furthermore, the researchers noticed that female chimpanzees and their young babies spend more time finding and eating crabs compared to adult males. The group of lactating and young female chimpanzees was the frequent consumers of river crabs. Their babies lined up and waited to be fed, while the younger ones — who understands the laborious work of finding crabs — came with their mothers to dig. Koops said that one of the possible explanations for this discovery is that crabs contain fatty acids and micronutrients that are good for both the mother and baby’s health.
What will be the impact of this study?
Chimpanzees are our closest living family in the animal kingdom. Past studies found that human ancestors ate fish, turtles, and other aquatic animals way back two million years ago when they left the comforts of the forest and decided to settle in the savanna. Matsuzawa, one of the researchers of this project, said that humans might have been eating aquatic animals since the earliest humans lived in forests for over four million years ago.
If chimpanzees eat river crabs, then it is possible that humans — as far as four million years ago — already ate aquatic organisms as a source of food to survive the drastic change in the environment.
The results of this study can help us understand that marine organisms are a vital source of nutrition, and it somehow helped in human evolution. The study presents an idea and a step towards finding out when and how humans began to eat aquatic animals.