Hassett Brenna - Growing Up Human: The Evolution of Childhood

Also available in the Bloomsbury Sigma series:

Sex on Earth by Jules Howard

Spirals in Time by Helen Scales

A is for Arsenic by Kathryn Harkup

Suspicious Minds by Rob Brotherton

Herding Hemingways Cats by Kat Arney

The Tyrannosaur Chronicles by David Hone

Soccermatics by David Sumpter

Goldilocks and the Water Bears by Louisa Preston

Science and the City by Laurie Winkless

Built on Bones by Brenna Hassett

The Planet Factory by Elizabeth Tasker

Catching Stardust by Natalie Starkey

Nodding Off by Alice Gregory

Turned On by Kate Devlin

Borrowed Time by Sue Armstrong

The Vinyl Frontier by Jonathan Scott

Clearing the Air by Tim Smedley

Superheavy by Kit Chapman

The Contact Paradox by Keith Cooper

Life Changing by Helen Pilcher

Kindred by Rebecca Wragg Sykes

Our Only Home by His Holiness The Dalai Lama

First Light by Emma Chapman

Ouch! by Margee Kerr & Linda Rodriguez McRobbie

Models of the Mind by Grace Lindsay

The Brilliant Abyss by Helen Scales

Overloaded by Ginny Smith

Handmade by Anna Ploszajski

Beasts Before Us by Elsa Panciroli

Our Biggest Experiment by Alice Bell

Worlds in Shadow by Patrick Nunn

Aesops Animals by Jo Wimpenny

Fire and Ice by Natalie Starkey

Sticky by Laurie Winkless

Racing Green by Kit Chapman

Wonderdog by Jules Howard

For all the mothers, and all the fathers, and all the babies.
But especially for mine.

Mary, Mary, quite contrary

How does your garden grow?

With silver bells and cockle shells

And pretty maids all in a row.

We humans are animals and animals, as we all know, are weird. Everything from high school biology classes and David Attenborough documentaries, straight through to the rather striking performance art oeuvre of Isabella Rossellini, has shown even the most casual observer of the world that creatures great and small have developed a vast array of techniques for surviving on this planet. Animals burrow, swim and fly; some walk, some run and some sort of squelch along. The great fascination of generations of naturalists has been the plethora of responses to lifes ultimate question, loosely interpreted as: how are you going to get through it? Leave it to humans to come up with outside-the-box answers: a childhood that is waving farewell to its evolutionary origins from the back of a cab on the way to who knows where.

You are weird. Your baby is weird and you were weird as a baby. And after that? You just got weirder. And that is for reasons that include planetary domination, but also a long tale of penis spikes and hidden ovulation and fertile fat and monogamy and unripe and unready babies and the evolution of dads and the secret purpose of grandmas and some very, very strange parenting practices ancient and modern that make us the miracle that we are: the ape that never grew up. We, alone among the animals, have decided that not only do we want to live forever, we want to be forever young. We take an extraordinary amount of time to grow up. Our childhood is incredibly drawn out not just compared with other animals but other apes. We are terrible at getting pregnant, then when we do we undercook the baby and end up with a ridiculously helpless infant. We throw that infant off the breast and into a world of toddling terror sooner than any other species, but then we just sort of stay kids. For a really long time. When other apes are getting down to reproducing, we are still off in Neverland, playing and learning and doing what kids do.

Why should this be? The answer is in our evolutionary history, way out in the badlands of speculation, fossils and other subjects of the science of the past. The weirdness of us is the result of an uncountable number of tiny little decisions made by our parents parents parents and so on back for millions of years. To carry a baby or to park it? What kind of milk and how often? Prioritise fat or free-ranging? What to teach the baby and when? Stone tools or Babylonian schools? These types of incremental decisions are still ones parents are making every day and this matters because evolution isnt static. It isnt an arc of progress leading to our sublime selves, perfect and unchanging. Each parenting choice we made or that was made for us has resulted in the kind of human we are today. And the choices we make today are the ones that determine what kind of humans we are tomorrow.

The question this book is asking is what that weird, unique human childhood is for. What purpose does it serve in the functioning of our societies and our lives? What is the possible adaptive value of teenagers? Taking the biological stages of growth as a starting point, we can build a framework of how we shoehorn in different adaptive benefits to different parts of our childhood. To do this we need to understand a little bit more about how different species pass on advantage through the generations. There is often a focus in evolutionary thinking on the red-in-tooth-and-claw aspects of adaptation the eat-or-be-eaten survival-of-the-fittest scenarios are by their very nature pretty arresting, as Im sure the poor australopithecine Taung child we will meet later in this book could testify, had it not been snatched up and eaten by a very large eagle deep in the hominid past. At a species level, however, death is not necessarily the most critical part of an animals life. The most critical bit is the ability to grow into a successful adult who can support the continuation of their genetic material; dying is just something that gets in the way. Retraining our sights on the complex processes that underpin our growing up gives us the chance to really interrogate what it is that has made the difference in our species survival and success.

Throughout this book, we will look at childhood as money spent. Raising a child is an investment: in the future, in those genetic lines, in the propagation of a species or what might one day become a species. More critically, however, raising a child requires investment. There is a clear difference in the allocation of parental resources between the releasing a zillion eggs and hoping statistics are on your side versus the slow nurturing of a dependent over the course of years or even decades. But what is this immense, long-term investment we humans are making in our offspring?

Technically, what we offer is an inter-generational transfer of wealth inheritance in a variety of forms. This transfer of a differential potential for success down the genetic line is something proposed by prominent archaeological theorist Stephen Shennan as a deeply fundamental part of how human societies function, even in the halcyon imagined egalitarianism of the past. There are three possible ways to invest in a child; throughout this book we will see how each type of investment has paid off for our species, because this is definitely the one instance where we do not do it like the birds and the bees do it.

So, how do we do it? A basic ecological model of investment in offspring that we can use to explain frogs becomes a far more intricate beast when transplanted into animals that have more than one way of passing on advantage to their children. A frog having the stamina to hold on to its mate long enough to get some eggs fertilised requires a very different sort of investment from the one that educated you to the point where you are reading a book on the evolution of childhood with complicated terminology and an excessive number of footnotes of your own free will. What investments human parents can make in their children, and when and how they make them, shapes their life chances for the future. Not only that, but it shapes the societies they live in.