Chimpanzee moms play with their kids — even when they're hungry and tired
Study shows play is ‘so developmentally important’ for young chimps, it has to be a priority: researcher
Even when times are tough, chimpanzee mothers will carve out time to play with their kids, new research has found.
Scientists observing chimps at the Kibale National Park in Uganda found that when food is scarce, most adult chimps put playtime on the back burner so they can focus, instead, on survival.
But mothers, it turns out, prioritize play in good times and bad.
"I think what it tells us about chimps is that this kind of behaviour, this play behaviour, is so developmentally important in the lives of those young chimps that mothers have to keep doing it," Zarin Machanda, a biologist and anthropologist at Tufts University in Massachusetts, told As It Happens host Nil Köksal.
The study, co-authored by Machanda, was published Thursday in the journal Current Biology.
Machanda has been working with the Kibale chimps for nearly 40 years, and says there's nothing quite like watching them play.
"Chimps play all the time, especially if you're watching baby chimps," she said. "They chase each other, they tickle, they wrestle, they'll do somersaults and they'll play bite and play hit."
They have a "particular facial expression" when they do it, she said, that makes it obvious they're having fun.
"And they do laugh," she said. "When the chimps start playing, it puts you in a good mood."
The link between food and play
But while hijinks and tomfoolery is a normal part of chimp behaviour, she and her colleagues started noticing a big uptick in their play in 2016 and 2017.
"It wasn't, you know, just the babies playing," she said. "It was the adults playing with each other."
Food in the forest was particularly abundant during those years, she said. So the researchers theorized that the chimps simply had time and energy to spend on recreation.
They put that theory to the test, and an analysis of 10 years of observational data proved them right. When food was plentiful, the adult chimps played more. When food was hard to come by, they didn't play much at all.
They expected this would be true for both males and females, she said. In fact, they thought it might be an even more dramatic correlation for female chimps, because they require more calories to have and nurse babies.
But the opposite turned out to be true. Overall, adult females played the same amount no matter how much food was around.
Digging further into the data, they realized "it was actually the mothers that kept playing with their babies when food was poor," Machanda said.
"I always kind of say that, you know, the magic of science happens when you get these unexpected things."
One possible explanation, Machanda says, is that when food is scarce, chimpanzee mothers tend to break away into smaller groups, or sometimes go off on their own with kids.
That way, she says, there's less competition for limited resources. But there are also fewer young chimps around for their little ones to play with.
'Moms are always around'
And play, she says, is valuable because it's how animals learn. In the case of chimps, they're practising their motor skills, but also learning important social dynamics.
"So in many ways, this is the obligation of being a chimp mom, that you may be the only play partner for your baby," she said. "Moms are always around. You're always with your mom."
Playing with mom is a lot like playing with other kids, she says — a lot of tickling, chasing and wrestling. But there are also bonuses to having a bigger, stronger playmate.
"The other thing that you see with moms and really small babies is that they play the 'airplane game,' which is just this really cute," Machanda said. "The moms go down on their back and they hold their babies up in the air and swing them around."
Laura Bolt, a primatologist from the University of Toronto Mississauga who was not involved with the research, called the findings "interesting but not surprising."
"From an adaptive standpoint, it makes sense that mothers would use their energy to play even in conditions of shortage if playing will help the survival of their infants and juveniles," she said.
"It is in their best interests to ensure that their infants have the best chance of survival, even at some cost to themselves."
Machanda says the moms mostly seem to enjoy playing with their kids. "They certainly have their play face on," she said.
Nevertheless, she suspects they don't always want to do it.
"Sometimes the moms are resting on the ground trying to sleep or just shut their eyes and then their baby's bouncing on top of them," she said. "I'm anthropomorphizing, but like, the facial expression is, 'Please, just let me take a nap."
She's also seen a mother chimpanzee wrestling with her five-year-old while simultaneously nursing her newborn.
"I think a lot of parents can really kind of resonate with that image of this mom juggling, you know, all of these duties of motherhood," she said.
"Sometimes you see these mom chimps and you're like, 'I feel it. I get it.'"
Interview with Zarin Machanda produced by Talia Kliot
