Chimpanzees have a deep affection for mother and child, much like humans

A baby chimpanzee is hugging its mother. The DNA sequences of chimpanzee and human genomes are 99% similar. Photo by ERIC GEVAERT, ALAMY

Written by: GRANT CURRIN

　　Take care of babies around the clock for a full year, take care of up to 5 children, and maintain a tense and time-consuming relationship for more than a decade.

　　Sound familiar? Like human mothers, chimpanzee mothers devote significant resources to raising their offspring into healthy adulthood. Chimpanzees can live up to 40 years in the wild. From the rainforests of Uganda to the savanna woods of Tanzania, although chimpanzee communities vary and have their own quirks and behaviors, they have one thing in common: mother and child are closely linked.

　　In recent years, new research has raised concerns about chimpanzees' motherhood, while also bringing important information about the endangered species.

　　Due to habitat loss, hunting and disease, the ape population has declined by at least 70 percent, from 1 million in 1990 to 172,000 to 300,000 today. A better understanding of chimpanzees' social relationships can help conservationists identify factors that contribute to the prosperity of gorillas communities, such as habitat size.

　　The connection between chimpanzees is "actually hard to describe, like the love between humans," said Rachna Reddy, a postdoctoral researcher at Harvard University. For years, Reddy has been observing wild chimpanzees.

　　Let's take a look at the scientists' new findings that have changed our perception of chimpanzee mothers; in fact, they are so similar to humans.

Mother and child are deeply in love

　　Generations of primatologists have documented intimate relationships between chimpanzee mothers and adult sons, but it wasn't until last year that a study confirmed that this mother-child relationship is not only touching, but perhaps the norm.

　　Reddy and co-author Aaron Sandel spent three years in Kibale National Park in Uganda observing the interaction between 29 young and young male male male chimpanzees in the Nagago Chimpanzee community and their kind. Male chimpanzees no longer see their mothers as often as they used to, but after they meet, sons follow their mothers and spend a long time grooming them, which may be repeating the behavior of childhood.

　　Some mother-child relationships are even closer, with "about a third of adult males and mothers being best friends," Reddy said.

　　This lasting relationship between mother and child may exist in chimpanzee populations. This is very rare in mammals, as most males leave the group they were born after they mature. In chimpanzees, it is the females who create new groups, which is why the closest thing to female chimpanzees is their sons.

　　Even if young males don't leave the extended family, they face a difficult transition: struggling through the social class constructed by adult males.

　　The study also found that mothers played an important role in this transition: when their sons clashed with older males, mothers protected their sons and brought comfort through caresses.

The life of a chimpanzee mother

　　Sean Lee, a postdoctoral scientist at George Washington University, has been rethinking the conventional wisdom of the daily life of female chimpanzees.

　　For example, scientists have long believed that chimpanzee mothers are not sociable because they spend too much time with their offspring.

　　But with larger datasets and open-mindedness, Lee and colleagues found that mother chimpanzees spend at least as much time with other adult chimpanzees as their cousin bonobos, who are known for their penchant for living in groups.

　　In a study published earlier this year, Lee and colleagues documented the parenting behavior of bonobos in the Democratic Republic of congo. The researchers compared these observations to decades of chimpanzee data from Tanzania's Gombe Creek National Park.

　　Scientists counted how much time the two species spent on various activities, such as eating, moving, combing and playing.

　　Unsurprisingly, chimpanzee mothers spend more time with their babies one-on-one and less time with other chimpanzees than bonobos. But chimpanzee moms spend as much time on high-quality social events like grooming and playing as bonobos.

　　"It was exactly the opposite of what we expected," Lee said. The findings show that "chimpanzee mothers also need interaction and social time, and they do." ”

Shared grief

　　Studying captive chimpanzees also helps to understand the behavior of wild chimpanzees.

　　At the Royal Hamburg Zoo in the Netherlands, Moni is one of the lowest-ranking members of its community and has difficulty connecting with the other 14 chimpanzees. It sometimes stares at the chimpanzees and wants to groom them.

　　"She didn't know how to be a chimpanzee," said Zoë Goldsborough, a doctoral candidate at Utrecht University. She spent several months observing Moni and its community.

　　One morning, Goldsborough and colleague Kayla Kolff spot a stillborn baby in the fence; they realize that Moni doesn't interact with other chimpanzees, in part because it's pregnant.

　　On that day, the chimpanzee community was unusually quiet. Instead of avoiding Moni as usual, they sat down beside it, kissed her, held out their fingers for it to hold, or put it in her mouth.

　　Researchers know chimpanzees may be sad, but Moni's experience is the first to be documented: Chimpanzees ( at least captive chimpanzees ) comfort survivors who have lost loved ones, Goldsborough said. As lead author, she recently published a study on this behavior.

　　While other chimpanzees' strong emotional expression of Moni lasted only a few hours, the loss of the child helped it gain a foothold in the group: now, it was of medium status, with several peers grooming each other.

　　Whether or not he realizes that his death is "the element that distinguishes people from animals," Goldsborough said. Research has shown that chimpanzees also experience intense grief, and this is one of the many emotions we share with other close relatives of great apes.

(Translator: Sky4)