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Taï Chimpanzee Project / Orphaned chimpanzees can suffer all their lives from the absence of their mother

Male chimpanzees who lose their mothers early in life are less competitive and have fewer offspring than sons who continue to live with their mothers.

One of the biggest traumas we face is the death of our parents when we were children. Orphans can continue to suffer the negative consequences of the loss of their parents for the rest of their lives, especially in terms of growth and health.

New research shows that, like humans, chimpanzees stay with their mothers until their teens, after the age of twelve. A series of new studies show that orphaned chimpanzees are also disadvantaged in growth and survival. A new study in "Science Advances" of the "Taï Chimpanzee Project" in Côte d'Ivoire, a scientific project of the Swiss Center for Scientific Research in Abidjan, and of the Max Planck Institute of Evolutionary Anthropology in Leipzig shows that in addition , orphaned sons are less competitive and have fewer descendants than those who continue to live with their mother. The unanswered question is, what do mothers provide to keep chimpanzees healthy and competitive?

Researchers have developed three communities of chimpanzees in Tai National Park. They kept complete demographic data and took fecal samples to perform paternity tests on all new members of the community, for a period of up to 30 years. Principal author Catherine Crockford says: “When we study our closest living relatives, like chimpanzees, we can learn more about the old environmental factors that made us human. Our study shows that the presence and support of a mother during extended childhood years was probably also a trait of the last common ancestor that humans shared with chimpanzees six to eight million years ago. This trait probably played a fundamental role in the evolution of chimpanzees and humans."

The main theories of human evolution hold that the fact that the parents continue to provide food to their offspring until they have grown up has enabled our species to have the largest brain of all the species of the planet in relation to the size of our body. The brain is expensive tissue that grows slowly, leading to long periods of childhood. Continuing parental care in early childhood gives children time to learn the skills they need to survive into adulthood. These long childhoods are rare in animals, and are only matched by those of other great apes, such as chimpanzees.

Chimpanzees can have a long childhood, but after the age of four or five, when they are weaned, mothers rarely provide food directly to them. Most of the time, mothers let their offspring feed themselves. So what do chimpanzee mothers provide for their sons that gives them a competitive advantage over orphaned sons? We don't know the answer yet, but scientists have some ideas.

Learning from mothers

“One idea is that mothers know where to find the best food and how to use tools to extract hidden and highly nutritious foods, like insects, honey and nuts,” says Ms. Crockford. “Children gradually learn these skills during their childhood and adolescence. Presumably one of the reasons children continue to move and feed near their mothers every day into their teens is that looking at their mothers helps them learn." Learning skills that allow them to eat more nutritious foods may explain why great apes can afford to have much larger brains than other primates for their size.

“Another idea is that mothers pass on social skills,” adds Roman Wittig, final study author and Director of the Taï Chimpanzee Project.“Still much like humans, chimpanzees live in a complex social world of alliances and competition. It may be by watching their mothers that they learn when to form alliances and when to fight."

“The results have important implications for conservation,” explains Koné Inza, Managing Director of the Swiss Center for Scientific Research and President of the African Society of Primatology. “Chimpanzees are critically endangered in West Africa. Their number has fallen by 80% over the past 20 years. Hunting for chimpanzees today will not only reduce the number of chimpanzees of this generation but will reduce the number of chimpanzees of the next generation”. This is in addition to other factors that contribute to the rapid loss of chimpanzees, such as the cutting of forests and the transmission of human respiratory diseases to chimpanzees.

Download the original paper here : https://bit.ly/2FXsmtG

Video link : 
https://www.youtube.com/watch?v=CfYcF4I9Bso  

Contact : 

Dr. Catherine Crockford
Max Planck Institute for Evolutionary Anthropology, Leipzig

Dr. Roman Wittig
Max Planck Institute for Evolutionary Anthropology, Leipzig Prof.

Prof. Inza Koné Directeur Général
Centre Suisse de Recherches Scientifiques, Abidjan

Original p
ublication Catherine Crockford, Liran Samuni, Linda Vigilant, Roman M. Wittig

Postweaning maternal care increases male chimpanzee reproductive success

Science Advances, 18 septembre 2020



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