Round-the-clock infant care for a year. Nursing for up to five. An intense, time-consuming relationship that lasts more than a decade.
Sound familiar? Like human moms, chimpanzees pour immense resources into raising their offspring into healthy adults, which can live up to 40 years in the wild. Though chimp communities—which range from Uganda’s tropical rainforests to Tanzania’s savanna woodlands—are diverse, with their own quirks and behaviors, they all share the same foundation: Powerful bonds between moms and young.
In recent years, new research has brought chimpanzee motherhood into clearer focus, while also providing valuable information about this endangered species. (Read how animal mothers remind us a lot of our own.)
Due to habitat destruction, hunting, and disease, the great ape’s populations have fallen by at least 70 percent, from about a million in 1900 to between 172,000 and 300,000 today. Learning more about their social relationships can bolster efforts to protect the species by helping conservationists understand what factors, such as habitat size, chimp communities need to thrive.
There’s something about chimpanzee bonds “that's actually sort of indescribable, just like in human loving relationships,” says Rachna Reddy, a postdoctoral fellow at Harvard University who has observed the animals in the wild for years.
Here are more discoveries that are changing what we know about chimp moms—and revealing how similar they are to us.
Generations of primatologists have documented strong relationships between mothers and their adult sons, but it was only last year that a study showed these attachments aren’t just heartwarming—they’re likely the norm.
Reddy and co-author Aaron Sandel spent three years observing how 29 adolescent and young adult males within the Ngogo chimpanzee community of Uganda’s Kibale National Park interacted with other chimps. The male chimps didn’t see their moms as often as they once had, but when their paths crossed, the sons sought out their moms and groomed them for long periods, likely repeating behaviors from their childhoods.
Some had even closer connections: “About a third of adult males are essentially best friends with their mothers,” Reddy says. (See touching photos of animal moms and babies.)
This kind of lasting relationship between mother and son likely occurs across chimp groups. It’s also highly uncommon among mammals, as most males leave their birth group when they’ve reached maturity. With chimpanzees, it’s the females that find a new group, which is why a female chimpanzee’s closest relatives are likely to be her own sons.
Even though young males don’t leave their family, they face a tough transition: breaking into the social hierarchy of adult males.
The study also found that moms play a crucial role in this life transition by defending their sons during conflicts with older males, as well as offering comfort through touch.
Self-care for chimp moms
Sean Lee, a postdoctoral scientist at George Washington University, has been rethinking the conventional wisdom about female chimps’ day-to-day lives.
For example, scientists have long thought chimp moms aren’t that social, because they spend so much time with their offspring.
But using larger datasets—and open minds—Lee and colleagues discovered that chimp moms get at least as much quality time with other adults as their famously gregarious cousins, the bonobos.
For a study published earlier this year, Lee and colleagues recorded the behaviors of nursing bonobos in the Democratic Republic of the Congo. The researchers then compared those observations with decades of data from chimpanzees in Tanzania’s Gombe Stream National Park. (Read about Goodall’s experiences with Gombe chimps in her own words.)
They looked at the amount of time each species spent doing various activities, such as eating, traveling, grooming, and playing.
Not surprisingly, chimpanzee mothers spent more one-on-one time with their infants—and less time with other chimps—than bonobos. But chimp moms also took at least as much time as bonobos on high-quality social activities, like grooming and play.
“It was exactly the opposite of what we were expecting,” Lee says. The findings show that “chimp moms still need to get that social interaction and social time—and they do.”
Research on captive chimpanzees can also offer some insight into their wild kin’s behaviors.
Moni, one of the lowest-ranking members of her community at Royal Burgers’ Zoo in the Netherlands, struggled to relate to the other 14 chimps in her enclosure, sometimes staring at chimps she wanted to groom or pulling their hair.
"She didn't really know how to be a chimp,” says Zoë Goldsborough, a doctoral candidate at Utrecht University who spent months observing Moni and her community.
One morning, Goldsborough and her colleague, Kayla Kolff, discovered a stillborn baby in the enclosure, and realized Moni had been keeping to herself in part because she was pregnant.
The chimp community was unusually quiet that day. Instead of avoiding Moni like usual, the chimps sat next to her, kissing her and offering their fingers for her to hold or put in her mouth.
Researchers already knew that chimps likely grieve, but Moni’s experience may be the first documented evidence that chimps—at least in captivity—console the survivor of a loss, says Goldsborough, lead author of a recent study on the behavior.
Though the other chimps’ intense affection toward Moni lasted only a few hours, her loss may have helped her gain footing in the group: She’s now a mid-ranking chimp with several grooming partners. (See a compelling photo of mourning chimps.)
Awareness of our own mortality was really seen as something that “set animals and humans apart,” Goldsborough says, but research is showing that chimpanzees experience intense grief—just one of many emotions we share with our great ape cousins.