I WAS going to start this article another way. But that was before my 10-year-old daughter intervened. In fact, I had already begun writing when she bounced up and tried to scam me. She offered to bet me 拢10 that she could make an ordinary pencil write in the colour red. Alas for the budding entrepreneur, I refused the bet: she was too confident, so I suspected she had something up her sleeve. But I did let her reveal her trick. She took a lead pencil and wrote 鈥渋n the colour red鈥�. Then she laughed like a hyena and went off to try scamming her mother.
Our bright little spark has opinions about everything from video games and sports to books. She is learning basic algebra and coding, and her Taylor Swift expertise vastly outstrips mine. Yet, despite all this knowledge, she has years to go before adulthood. If she lives an average lifespan, a quarter of her years will be spent underage.
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The long human childhood is a real oddity. No other primate spends so much time becoming an adult. Over the course of our species鈥� evolution, along with more obvious physical changes, childhoods got vastly longer. Traditionally, palaeoanthropologists have paid little attention to children, but now that is changing. A spate of intriguing discoveries in the past few years is building a picture about human childhood: when this seemingly unproductive life stage expanded, why it is so long and what prehistoric kids got up to. The findings don鈥檛 just throw light on a dark corner of human evolution, they also reveal why childhood is so important.
Childhood is surprisingly difficult to define. 鈥淚t鈥檚 so basic and hard at the same time,鈥� says at the University of Victoria in Canada, author of . Western societies often use a straightforward chronological measure: we may become legal adults on our 18th birthday, for example. But that is far from a universal concept. 鈥淚n a lot of societies, they make that transition between child and adult based on whether someone has certain skills or a certain personality or certain abilities,鈥� says Nowell.
Defining childhood by biological markers of growth is problematic too. For instance, most of us are sexually mature long before 18, yet we keep developing long after that. 鈥淥ur skeletons finally finish off at about 25,鈥� says at the University of Central Lancashire, UK. Besides, as well as physical development, childhood is also, crucially, a time of mental development, of learning and play. And, at its most basic, it is when we are dependent on adults to provide food and other necessities. 鈥淔or me, childhood is a period when other people are investing in you,鈥� says Hassett.
However you measure it, though, the length of human childhood is exceptional 鈥� even compared with that of our closest relatives, the great apes, which all have long childhoods too. Hassett compares us to bowhead whales, which only hit sexual maturity . However, they often live for over 200 years, whereas humans rarely reach 100. 鈥淲e鈥檙e spending a quarter of our time as juveniles,鈥� says Hassett. As a proportion of a lifespan, that is inordinately long.
And it isn鈥檛 just a matter of length. Human childhood is also qualitatively different. Primatologists think of monkeys and apes as going through three stages: infant, juvenile and adult, with infants spending most of their time clinging to their mothers and juveniles moving around more freely. In contrast, humans have five stages, says Nowell: infant, child, juvenile, adolescent and adult. 鈥淐hildhood and adolescence are two new phases of the human life history that are inserted into this more typical primate pattern,鈥� she says. The child phase lasts from weaning until the eruption of the first permanent molar tooth (between the ages of about 2 and 6). Adolescents are physically able to reproduce, but are still maturing in both body and mind. Although there is now evidence suggesting that, like us, chimpanzees experience an adolescent growth spurt, nevertheless, human life history has clearly been radically reshaped. When did this happen?
Childhood evolves
The story of human evolution spans some 7 million years. Unfortunately, the oldest hominins are only known from a handful of fossils, so we have little or no information about their childhoods. 鈥淚t鈥檚 a spotty fossil record,鈥� says at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Only with Australopithecus, which lived in Africa between about 4 million and 2 million years ago, do we start to have enough specimens to say something meaningful. , Gunz and his colleagues scanned the skulls of eight Australopithecus afarensis from over 3 million years ago. They found that youngsters had smaller brains than modern chimpanzees of the same age, while the brains of adults were a bit larger than those of adult chimps. 鈥淭his can only be if they grow their brain for a longer period of time,鈥� says Gunz. So it looks like childhood was already lengthening somewhat over 3 million years ago.
Our own genus, Homo, emerged between 3 million and 2 million years ago. Compared with earlier hominins, the first Homo had significantly bigger brains and were committed to walking upright. They made and used stone tools and ate a broader diet, including meat. But did they also have longer childhoods than earlier hominins?
There is , but the clearest evidence comes from a Homo erectus youngster from near Lake Turkana in Kenya. , also known as Nariokotome Boy, lived about 1.6 million years ago. He seems to have been about . His brain indicates a faster growth rate than that of modern humans, says Hassett, 鈥渂ut it鈥檚 on a different trajectory from the earlier australopithecines鈥�. And the implications of that are clear. 鈥淏y the time you get to H. erectus, around 2 million years ago, there鈥檚 a significant extension of childhood,鈥� says Nowell. What鈥檚 more, that the .
Our own species, Homo sapiens, evolved around 300,000 years ago. We follow the same five-stage pattern as earlier Homo, but 鈥渆ven more slowed down, even more elongated鈥�, says Nowell. This lengthening of childhood may have evolved gradually over millions of years, or there may have been rapid spurts followed by periods of stasis, says Gunz. Without many more fossils, there is no way to tell. Nevertheless, we can ask why it happened.
One much-discussed idea centres on the difficulty of human childbirth. Compared with other apes, human labour is extremely painful and dangerous. This has been attributed to our bipedal stance, which led to our hips becoming narrower, together with the evolution of bigger brains. Put simply, we are pushing a large object through a small hole. In 2022, at Western Washington University in Washington state and her colleagues showed that pregnancy began changing as early as 6 million years ago. 鈥淚nfants kept growing larger and larger, and their brains got larger along with them,鈥� says Monson. As a result, human babies must be born when they are still underdeveloped and helpless. 鈥淲e always talk about the first year after birth as being almost a second gestation,鈥� says Nowell.
Nevertheless, this alone can鈥檛 explain the evolution of longer childhoods. Once babies are born, they are free to grow, so, in theory, could develop rapidly to adulthood. But they don鈥檛. This means we need to look beyond childbirth to prehistoric children: how they lived and what they were doing. Until the past few years, archaeologists have neglected to do this. Indeed, they often regarded children as a nuisance who made a mess of important artefacts by playing with them. 鈥淲e weren鈥檛 thinking about the lives of those children,鈥� says Nowell. That is now changing. And as our picture of prehistoric childhood expands, so too does our understanding of why this stage of life is so important.
Stone Age kids
Take this charming tableau. In B脿sura cave in Italy, footprints and other traces reveal what looks for all the world like . There were five people: a man and a woman, a teenager and two children, the youngest about 3 years old. They walked barefoot, using burning sticks to light the way, and went deep into the cave. At one point, the youngsters seem to have collected mud from the floor and smeared it onto a stalagmite. 鈥淢aybe it was a rainy day in the Palaeolithic and they went exploring,鈥� says Nowell.
Perhaps these children were also displaying a creative urge 鈥� because we know that even very young kids were involved in making art. A 2022 study looked at hand stencils painted on cave walls in Stone Age Europe. Some were so small that they must have been . Prehistoric art probably had meaning for the people who created it, but sometimes it could have been made just for fun. And there is plenty of other archaeological evidence that fun and games have long been a part of childhood.
At Laugerie-Basse in France, for example, archaeologists found a bone disc dating from between 11,000 and 18,000 years ago. On either side is a picture of a deer in a different pose, and there is a hole in the middle through which string could be threaded. Nowell and her colleagues point out that if the string were twisted and released, , creating the illusion of the deer moving, like a child鈥檚 flip book. Owl-like plaques from Bronze Age Spain . Most early toys were probably made of perishable materials like wood, so have rotted away. But other forms of play can still be seen. At Le Rozel in France, there are , as if playing a chase game like tag.
Decades of research leaves no doubt that play has a serious purpose 鈥� it is a way of learning new physical, psychological and social skills. And in prehistory, it may have had an additional role that made it even more crucial for our ancestors. The appearance of certain toys in the archaeological record coincides with technological innovations, such as the wheel and weaving, hinting that child鈥檚 play inspired some key human inventions.
Prehistoric children also needed to learn skills for survival. A study published in 2022 looked at young foragers in 28 modern societies and found that, while children easily learn to collect fruit and shellfish, the exploitation of resources such as tubers and game isn鈥檛 mastered until adolescence or adulthood. This, the researchers concluded, supports the idea that a long childhood . So too does where artefacts created by expert flint-knappers are mixed with amateurish efforts 鈥� suggesting children were trying their hand at it.
The overall picture is that prehistoric children had rich and complex lives, filled with different activities, and were always learning and : 鈥渓earning about , alongside basic skills acquisition and everything that makes us able to operate as humans in this world鈥�, says Monson.
This long phase of learning has obvious benefits for children. Intriguingly, it may also shape the societies in which they live. 鈥淎s children grow, who they choose to learn from changes,鈥� says Nowell. In hunter-gatherer societies, children start by learning from their parents, but as they enter adolescence, they start to seek out other adults 鈥� . Teenagers may thus be a linchpin in the spread of innovations. 鈥淣ot all knowledge is carried from one generation to the next,鈥� she says. 鈥淚 think that children and teens are particularly important in deciding what they carry forward.鈥�
In fact, youngsters probably played an even bigger role in prehistory, because there were so many of them. A 2008 review suggested that kids made up between , a far higher proportion than now. 鈥淐hildren would have been a key demographic in ensuring the survival of the overall community,鈥� says Nowell.
It is tempting to wonder whether modern parents can learn anything from our forebears (see 鈥淧alaeo-parenting today鈥�, below). But Nowell believes that the recent research holds a subtler lesson. 鈥淚t changes how we see children and their contributions to their communities,鈥� she says. There has been a popular notion that children are just empty vessels that we must fill with knowledge. This is flat out wrong, she argues. 鈥淐hildren have always had agency. Children have always made important contributions to the overall well-being of their communities. And they have a role in shaping where our societies are going in the future.鈥�
Palaeo-parenting today
Humans have been parenting for a very long time. So can we learn anything from prehistoric parents about how to raise our children?
"The internet and the world are full of people telling you how to palaeo-parent," says Brenna Hassett at the University of Central Lancashire, UK, author of . There are messages about the ideal way to carry a baby, how much freedom to give your kids and what to feed them 鈥� all extrapolated from archaeological studies. But these studies were never intended as parenting advice, says Hassett.
The reality, she says, is that humans are defined by an immense adaptability. What was sensible parenting 100,000 years ago when we were all hunter-gatherers isn't necessarily sensible in an agricultural society with a global internet and a disinformation problem.
"My message would be: just stop freaking out about how your kids are sleeping or being carried," says Hassett. "There is no one true evolutionary way. We are continually changing."
Michael Marshall is a freelance writer based in Devon, UK
