Why do humans have to grow up rather than emerge from a cocoon like butterflies?

As a child, did you ever think to yourself that you’ll never stop playing with toys or you’ll never like a member of the opposite sex whatever the adults say?  If so, do you remember when and why you changed your mind?  The question is oddly impossible to answer. 

Childhood is a wonderfully weird thing, though I don’t think most people would phrase it that way.  We are all of us, from Mother Theresa to Adolf Hitler, Albert Einstein to the latest recipient of the Darwin Awards, born into this life as an almost helpless infant, equipped with more or less five skills, crying, eating, urinating, defecating, and sleeping.  Previously, while in the womb itself, we began life as a single fertilized cell with no skills at all.  Forget skills, we start life without any shape as one cell becomes two, becomes four, sixteen, thirty two, sixty four, and so on.  At first, all of those cells are exactly the same.  It isn’t until the fourth day that an outer and inner layer begin to form, and not until the second week until we are divided into three layers, the ectoderm, mesoderm, and endoderm.  While all complex life on Earth follows a similar pattern, emerging from a single cell whether vertebrate or invertebrate, what occurs between birth and adulthood varies significantly to say the least.  For example, most of our mammalian cousins begin life far better equipped to survive than we do.  You’ve probably seen an antelope literally fall out of the birth canal, hit the ground with a thud, only to jump up on seemingly unsteady legs and start running after its mother as though it has been doing it for years.  While not quite an adult, which is generally defined as the age of sexual maturity, infants of many species are born much closer to being fully functional, autonomous beings than humans.  The time to sexual maturity varies, but generally speaking, small mammals like rabbits and mice take only a few months, medium size animals like dogs require about a year, larger animals like elephants and blue whales can take close to two decades, around the same amount of time as a person, though even that can be deceiving when a young elephant or whale is still far more capable than a young human.  Nor is being born with roughly the same body shape as your adult form the only strategy for growing up.  Particularly among insects and amphibians, the infant looks nothing like the adult as they move through pupal and larval stages, sometimes more than once.  At each stage, they cast off their old body and emerge as an entirely new creature.  The butterfly is perhaps the most famous of these transformations, changing inside a cocoon from a lowly caterpillar to a gorgeous, flying creature, but far from the only one.  Consider a barnacle, those crusty things that stick to the sides of boats.  You might not be aware that they begin life swimming freely in the water, a “nauplius larvae” armed with hard shells for protection as they feed upon microscopic organisms.  From there, they transform into their cyprid form which is also free swimming, but no longer eats, searching for their final home instead using special antennae.  Once found, they attach themselves with cement glands, before undergoing a metamorphosis into their adult, stationary state, growing a hard carapace and emitting feathery appendages known as cirri to trap food drifting by.  Most are hermaphrodites, able to impregnate and get impregnated using a tube that sticks out to a neighbor to fertilize their eggs.  Interestingly, barnacles are crustaceans the same as crabs and lobsters, but the relationship is only evident in their larval stages as the adult form is entirely different at least on the outside.

What, you are probably asking, does this have to do with people?  Nothing and everything if you consider that the progression from infancy to childhood, onward from adolescence to adulthood doesn’t necessarily have to be the way it is in humans.  Beyond how other animals do it, we can certainly imagine a world where we spring into existence fully formed, our adult selves from day one, or at least one where we pass through the different life stages similar to an insect emerging from a cocoon.  Instead, we spend two to three years in the curious state of being a toddler, where we clearly know and remember things in our own limited way.  Toddlers learn to speak, recalling words and syntax, they learn their numbers, the alphabet, colors, their family members, how to navigate the house, how to listen to and frequently object to instructions from their parents, and more.  They remember all of this and can recall recent events in their lives, commenting on them in their own simple, sometimes comical way.  They have experiences that in their own minds they consider positive or negative.  They laugh, they cry, they even tease and try to make little jokes of their own.  As anyone with any experience with a 30-month old knows, they certainly have a mind of their own and can be surprisingly opinionated and willful.  They will, however, remember none of this.  When you look back on your life, it’s as if almost four years of it simply didn’t happen.  Rather than remembering being born and growing into your childhood form during that period, it’s as if you awoke from a dream, finding a handful of scattered, disconnected, sometimes vivid, sometimes false memories are all that’s left of your existence before kindergarten.  This is because we are born without fully formed brains, specifically parts of the hippocampus and prefrontal cortex are not yet developed enough to generate and store context rich, narrative memories, and like almost everything else in the way humans grow, the ability emerges gradually rather than all at once.  Thus, becoming a child seems closer to waking up than being born, which might well be an experience unique to human beings and our closest cousins, the primates.  While we cannot say for sure how other animals develop their mental faculties, much less what an individual elephant might remember when, chimpanzees, for example, are born almost as helpless as we are.  Like us, their brain and bodies are not fully formed.  They are carried at first by their mother before learning to walk and explore their environment over a period of about five years.  Over the next three, they become more independent, learn to use simple tools, and increase their social skills.  Between eight to twelve years old they are considered adolescents, transitioning through puberty before full adulthood.  Many scientists have remarked on the similarities, frequently relating it to the fact that such large brains would not make it through the birth canal if they remained in the uterus to mature as much as other animals, and so evolution turned to infancy and childhood to serve as an extended period of development outside the womb.

From this perspective, we might say we are not truly born until well after the moment we emerge from our mothers, but considering the brain continues to develop into early adulthood, that only makes the situation stranger because there’s no real means to identify a before and after, when we can say with surety, “I am my adult self.”  By grade school, you possess narrative memories and the faculty to read, write, perform basic math, follow instructions, take some measure of responsibility, form friendships, and more.  In some eras people have been crowned kings and queens before puberty, or less promisingly been forced to work in factories, the same as if they were adults.  At eight years old or even younger, you are a functioning human being in almost all respects except the ability to reproduce and shall we say the judgement and wisdom that comes with age, but of course, consciousness being as simultaneously all consuming and unaware as it is, you certainly don’t know that at the time.  If you ask an adolescent or a teenager what their future selves hold for them and when they will abandon their current, immature fancies, they can’t explain how their brains are changing or developing, can’t anticipate what will come as they age, or explain to you how they will view the world differently in just a few years.  Instead, they are entirely in the moment, complete in themselves, and are more than likely to tell you they have all the answers an adult does, don’t need to know anything more, and to keep your advice to yourself.  As a child, did you ever think to yourself that you’ll never stop playing with toys or that you’ll never like a member of the opposite sex whatever the adults say?  If so, do you remember when and why you changed your mind?  The question is oddly impossible to answer.  Most of us simply grow out of it, though we can’t say exactly when or why because we change along with our brains, being capable of thinking one way one day but not the next without being capable of pinpointing exactly what day that was or what the underlying alteration to our internal wiring.  We are the product of our entire brains, but we have access to the workings of only a small portion, making our conscious selves something like a little dingy floating atop a massive ocean, changing position with the waves and the tides with precious little control over those where we move and when.  Fortunately or unfortunately, we are blissfully unaware of this.  Instead, whether we are not yet fully developed, pushing middle age, or even one foot from the grave, we always feel like our complete selves, albeit perhaps with more aches and pains than we remember when we were young.

This, perhaps, is the strangest thing of all.  You are not the person you were as a toddler in almost all respects to the point where you can’t even remember being a toddler in the first place.  You are not the person you were as a child in most respects, though you can remember it, sometimes with advantages.  Even after entering adulthood, our brains and bodies change to the point where we are replaced almost in our entirety every seven to ten years.  Though each type of cell is on its own cycle, white blood cells only live for a few days to a few weeks, epithelial cells in our guts a few days, skin cells a few weeks, fat cells and bone cells about 10 years, muscles about 15 to 20.  With the exception of your brain, you are a completely different person than you were twenty years ago in almost all respects and even within your brain, though the neurons themselves might remain the same, being the longest living cells, the wiring is constantly evolving, making you both you and not you at the same time.  It is consciousness and consciousness alone, that dingy floating on an ocean, in this case of both mind and body, that creates a coherent narrative out of what are essentially ever changing parts.  Philosophers have long used a thought experiment known as “Theseus’ Ship” to capture what changing parts means to a constant whole.  Imagine that Theseus has a mighty ship, unique in all the world for its naval capabilities.  If you replace a single plank, everyone would agree that it remains Theseus’ ship.  If you replace two, three, four, five, even ten, they’d say the same, but what if you replaced half of them, three quarters, ninety percent?  At what point is enough of the ship replaced that it is no longer Theseus’ original?  Of course, no one can say for sure as quite frequently in real life, there is no clear point at which one thing becomes another.  At one extreme, some might claim that even should every part be replaced, if the parts are the same in all respects it will be Theseus’ ship forever, even if you kept cycling the planks in and out indefinitely.  Others are likely to take the view that once the replacement accounts for somewhere over 50% of the ship, it starts becoming something new.  Though we are all like Theseus’ ship in the sense that our bodies are constantly being replaced save for the around 5% of our weight that accounts for our brains, neither position is really satisfactory from the perspective of the self.  If all of you were to be replaced, how would you be you?  Wouldn’t you be a clone or something else entirely?  If everything except your brain is replaced we can understand how you are still you in principle, but in practice why do we feel the same and not like we are gifted with a new arm every ten years like a new car?

In a real sense, you are the mystery lying in between.  We are ourselves because of our life history, our memories of the past that make us who we are today, and yet we experience this as a whole that simply doesn’t exist and has never existed, from the time we were infants onward.  It might seem like an incongruity, a classic unsquarable circle, but if it wasn’t true, you wouldn’t be you, however you came into the world.