The Ape That Wouldn’t Grow Up


“It takes people years to see that there is something un-childish about the condition of childhood, that it is not merely a temporary state of innocence but a zone of pure philosophy”

- Andrew O’Hagan, in ‘Leave the kids at home and go see where the wild things are’

“Mommy, where are we?” I asked during a transatlantic flight from Montreal to Lisbon. “We’re still flying over the ocean” answered my mother. Baffled and looking into the darkness that extended beyond my oval window, I replied: “Yes I know! but on which planet? Portugal or Canada?” You see, in my six year-old head lay an intricately woven cosmos of fantastical concepts to which my parents were oblivious. As I understood it, each country was a planet, each with its own oceans, and aircrafts were inter-galactic flying devices transporting passengers to their interplanetary destinations.

I also believed that cats and dogs were different sexes of a same species (cats were females, of course), cars had faces and emotions (our red chevy was a temperamental old man), bad people were hired to get killed for real in movies, and about half the world was made up of Benjamin Buttons (I constantly tried to guess if a person was growing older or younger).

… And little else do I remember of this lost land. Puberty, like a bad night out, has virtually erased all that is left of that mystical universe I inhabited in my head. By the time adolescence showed me the door, I knew I would spend a good part of my twenties nursing the hangover from my teenage years. At 27 (ahem, 28) childhood is nothing but a distant memory of that time when shit hadn’t hit the fan yet.

But while shit does hit the fan eventually for all mammals – and by this I mean sexual maturity, the proverbial ‘coming of age’ and all the reality checks that come with it – humans are the only species lucky enough to be graced with four years of pure radiant bliss, a time of suspended growth. That bracket of infinite magic, childhood.

True, childhood is tainted with all that is dark and evil in human nature – I will not soon forget my ‘Lord of the Flies’ moments – but from the perspective of our evolutionary journey, of our own coming of age as a species, childhood might just have been the most perfect invention of all. It is the cushiest season, the most carefree and glorious of times. And it may very well be the reason for our overwhelming success.

The evolution of childhood (in red), unique to Homo species which has been increasing for the past two million years

We might like to think of the four seasons of life, but we do in fact have five: infancy, childhood, juvenile, adolescence (right after puberty), and adulthood. Most mammals progress from infancy to adulthood almost seamlessly, without the growth-spurts, the growing pains, the voice changes and acne-ridden faces. Highly social mammals, like wolves, wild dogs, lions, elephants and primates, postpone puberty by inserting a period of juvenile growth between infancy and adulthood. Puberty, marking the onset of sexual maturity, is delayed to allow for larger brains and the acquisition of proper life-skills. But only in the human species do we find a 5th season: childhood – a well defined step both physiologically and behaviourally, spanning roughly from three to seven years of age.

Relative to our body size, the human brain is bigger than that of any other animal, but our human bodies constrain the size of our heads at birth. In fact, during the last part of the 3rd trimester of pregnancy, the human fetus is so large that it presses against internal organs and constricts blood vessels. We have no choice but to slow down our growth and then rebound after birth to catch up to the size we would have had if growth had been continuous.

Our journey to adulthood is in fact rather counter-intuitive from an economic and even logical point of view. Its sinuous course, more akin to the stop-and-go motion of a highway traffic jam, leads us first into a period of rapid growth immediately after birth, then a period of rapid decrease in growth rate until the age of four, followed by a period of almost arrested growth that lasts until our juvenile years, at which point we hit puberty and grow up to 7-9 cm per year! (that’s about three inches per year).

Children at the AADHU/CYCA Centre for Orphaned Children in Kenya, Africa. I am particularly fond of this project because it is not affiliated with any religious organizations

Children at Kibera, Kenya

Childhood is defined by the period after weaning, which in nonhuman primates marks the beginning of independence since individuals can now walk and fetch food on their own. But not so for humans. There is no society on earth in which children deprived of care by older individuals, survive.

Due to the nature of our growth pattern, which is not equal for all body parts, our brains achieve adult size when our body growth is only at 40% complete. This leaves us with small bodies, small digestive systems with immature dentition, and big heads that require high-quality foods (low in volume, high in nutrients) that we cannot get hold of on our own. It isn’t until the age of seven when significant milestones of dental and brain maturation are reached that we are able to adopt an adult diet and shift to a new plateau of cognitive functions (and realize countries are not planets…).

The head, limbs, and body grow at different rates, resulting in a human adult with proportions completely different from those of the newborn baby. Growing in this way allows us to keep our ‘cute’, infantile looks for longer than in any other species of mammals

… But why take this four-year detour if all paths lead to Rome (or adulthood)?

One favorite explanation is our dependence on culture and on learning for survival. For all intents and purposes, childhood can be viewed as en extended coffee break, where the day’s activities are arrested so that we can catch up with the the New York Times, the latest celebrity gossip and finish that Sudoku puzzle. It allows for an extra period for brain growth and time for acquisition of technical skills, time for socializing, playing, and the development of social roles and cultural behaviours. It is effectively a pit-stop, a period of waiting, an oasis of protection, a state of lower nutritional requirements and of low mortality.

Age (in years)

Probability of death by age of rural Gambians. Note how low this is for children

Some researchers even view childhood as a sort of parasitic stage, a way to selfishly elicit parental care after infancy because we maintain a ‘cute’, infantile appearance for longer than any other mammal species.

From the mother’s perspective, having offspring that pass through childhood reduces the interval time between births. Weaning time is what sets the pace between births – if you are done breastfeeding, your are ready to go – and in preindustrialized societies this averages at three years, which coincides with the onset of childhood – a stage when we are so ‘cute’ that just about any grown-up (especially grandpa and grandma) will offer to take care of us. So while the average birth interval for chimpanzees is about five years (age at which chimps become independent), in humans this interval averages at about 3.6 years… now consider the much lower weaning average for industrialized societies (six months to a year) and our overcrowded planet will start to make sense.

But if you’ve cringed at the thought of lending your breast to your offspring for more than six months, you’re not alone. In the United States, for example, women receive conflicting advice about when to wean their children from breastfeeding. The American Academy of Pediatrics recommends one year, while WHO and UNICEF recommend at least two years and many physicians consider six months to be extended breastfeeding, while some health professionals question the motives of women who nurse for more than a year. Women have even been known to hide the fact that they are still nursing an older child from disapproving health care professionals or family members. But the reality is that in many non-Western cultures children are routinely nursed for three to four years, which is likely the more ‘natural’ state of affairs.

Childhood is then the perfect ‘parking space’ for offspring and avoids us having to choose between producing few expensive, large brained babies, or many smaller-brained offspring. It lasts about four years, just enough time for your first-born to hit childhood so that a second one can be on its way. Because weaning and childhood go hand in hand, it sets the pace at which a mother is ready to bear another child so that she is not overwhlemed with a Lilliputian army of defenseless babies, but rather is able take care of one baby at a time, unless you have octuplets… nature errs too (in which case, good luck to you).

Me, an ape refusing to grow up

At seven years of age, our 1st permanent molars come in. In primates, this marks the onset of independence but for humans this is just the beginning of our long, arduous march to adulthood. While chimpanzees are ready to be be competent parents at about 10 to 11 years of age, humans remain largely dependent on theirs for a staggering 20 years!

(Unless you complete half a university degree, move countries twice, take four years to complete a second degree, take 2 gap years, a Masters and now a PhD, in which case you are still, at least partially, in a state of dependency at 27. Ahem, 28).

But whichever the case, as a species we seem to have evolved into the eternal pupil. Instead of striving to be adults, our journey has been about prolonging and inserting evermore states of dependency, forever extending the umbilical chord uniting us to our parents, stretching it until we must grow our own with our very own offspring. Of all our closest relatives we are the ones with the most childish appearance, the ones who grow the slowest, who play and learn for the longest. We are the forever young apes. The apes that refused to grow up.

While I now know that cats and dogs belong to different species, there is still much I don’t know about my own species, and so I find refuge in the safety of school where I get to look up to taller, bigger people to teach me wondrous things. And as London spreads before me from my 13th floor student residence window on the eve of my 28th birthday, I’m thinking… “Who will come out and play?”.