Why Babies Don't Seem to Tire of Laughing at the Same Joke

What my toddler taught me about humor.

Posted Sep 18, 2019

Every time my baby laughs, I am reminded what a strange emotion laughter is.

"The giraffe said, 'I'm the tallest animal in the zooo-ooh-ooohhh,'" I say in a sing-song voice for what feels like the hundredth time in the span of a few minutes, and rejoice in watching my 21-month-old toddler laugh uproariously each time. She usually laughs more when I give a little bit of a verbal "build-up" to my "jokes," so I try it this time. I go "....the tallest animal in the.............uhhhhhh.......zoooo-oooohhhhh," and she laughs even harder than the last few times.

My daughter amazes me in new ways each day, but the first time I remember being actually awed was the time she demonstrated a sense of humor more sophisticated than laughing at high-pitched noises. "OMG. Babies have a sense of humor too," I remember discovering, as she told us her first "joke" — a gurgling sound that only she, and by extension we, found funny. This was interesting to me because she was actively doing something that was to her mind funny in order to make us laugh.

If you think about it, laughter is a pretty strange emotion. It has no obvious survival value, and so it's harder to understand from an evolutionary standpoint than, say, fear.

The prevailing evolutionary theory for humor has its basis in the fact that primates such as chimpanzees exhibit a rudimentary form of laughter, usually vocalized as a pant-like sound, in response to "social play." Laughter, in this context, is an indication to the playmate that everything is okay, and that playful interactions may continue. The primate evidence indicates that human laughter in its rudimentary form has evolutionary origins dating back to primates that walked the Earth at least 6.5 million years ago.

A lot has changed since then in terms of the functions of humor and its cultural and social contexts. But the explanation for why laughter is so important for us as a species lies in the fact that humans (and indeed all primates) are intensely social creatures. In fact, the accepted explanation for the large brain-to-body-size ratio in primates is that primates need a larger brain because their form of social behavior is more complex than that of other animals. Being part of large tribes has been such a win for our species evolutionarily speaking, and the strategy that led to this victory, according to the "social brain hypothesis," could just have been the development of language, and, by extension, humor.

"One little duck with a feather on her back, she led the others with a moo moo moo......WAIT A MINUTE! DUCKS DON'T SAY MOO!" Each time my daughter hears this rhyme, she bursts out in laughter. She's nearly two now, and at an age where her "worldview" is slowly but surely expanding. She knows that ducks quack and cows moo, and not the other way around. The incongruity in the rhyme tickles her funny bone, just as incongruity is one of the most common stimuli that makes adults laugh, too.

What's even more interesting is that she laughs at the duck rhyme in a raucous, almost-fake manner, almost as though she knows that this is something that ought to be funny, although it might not be intuitively so. And this is a huge step for her, to go from the peekaboo kinds of spontaneous laughter to this almost adult-like comprehension of what it means for something to be funny.

My daughter genuinely loves to laugh. She's always waiting for the smallest reason to burst into her little giggles, and the joy in her face when she does find such a reason is only partly due to the stimulus itself, and more due to her happiness at finding something to laugh at. And once we provide her with something that she does find funny, good luck to us, because she's going to make us repeat the same joke over and over until we are tired of it.

It strikes me as odd that not too many adults I know are the same way. We go about our lives, laughing only when absolutely forced to. Somewhere along the way, laughter loses the joy it once held in our lives. We don't wait eagerly, like my daughter does, to laugh out loud. We don't anticipate the punchline in as enthusiastic a manner as she does. We forget that often it's not the joke itself that brings us joy, but the act of laughing. Being around children reminds us of that, and of the fact that humor is inherent to the human condition.


Gervais, Matthew & Wilson, David Sloan. (2006). The evolution and functions of laughter and humor: A synthetic approach. The Quarterly review of biology. 80. 395-430. 10.1086/498281. 

Dunbar, R.  (2016, March 03). The Social Brain Hypothesis and Human Evolution. Oxford Research Encyclopedia of Psychology.