Compared with other species, humans have childhoods that are unusually long and demanding – especially for parents. And they are getting even longer. By Paul little.
You can find Brenna Hassett described variously online as a bio-archaeologist, biological anthropologist, or an osteo-archaeologist.
“I study the human remains part of the human past,” explains Hassett, a researcher at University College London. “The skeletons and particularly the teeth. That falls under something called biological anthropology, but I also do the digging, which is the archaeology.” So, a sort of dental amalgam.
Her book Growing Up Human is a millennium-spanning, multifaceted account of how and why we have evolved to have a childhood that is unique among species. And it all comes from looking at old teeth.
“Teeth are essentially a fossil in your mouth,” explains Hassett. “A tooth forms once, so it has a series of incredible regular structures, which means we can tell daily episodes of growth while your teeth are forming, which is, of course, childhood.”
Fortunately for her research, which clearly runs on molar power, teeth tend to stay around even after other human remains have disappeared. “They capture the chemistry of the growing environment; they capture the stresses and the diseases that kids pick up. They are a brilliant record.”
Over the course of human evolution, teeth have changed as what we eat has changed.
“When your teeth come into your mouth is linked to different life history goalposts. When most primates stop breastfeeding, they get that first molar, because they’re going to chew food now and they need that to happen. Your second molar comes when you’re able to eat all the foods all by yourself. And then you get that third molar[wisdom teeth], the one that gives us humans so much trouble, at sexual maturity.”
Drilling down, as it were, Hassett can work out the daily schedule of how animals were growing. It is possible, for instance, to deduce that a two-and-a-half-million-year-old fossil that looks like a 6-year-old’s teeth is actually from a 3-year-old.
Which means that, “we can look at that and go, ‘Actually, that creature had a faster childhood. They did not take the time [we do]. They grew more like an ape.’”
But what exactly is childhood? A popular definition is the period between being a baby and becoming a baby maker. Hassett thinks that doesn’t quite cover it. “I’d say childhood is the period where you are invested in, before you go on to being an investor.”
After all, many people don’t have kids, but that doesn’t mean they remain children.
“They definitely go on to pour resources into society in some way or another. So I use an investment threshold, because our human societies are a lot more than just biological reproduction.”
Her story of childhood starts before the sperm and ovum even get together. Our long childhoods are so unusual that it was necessary for her to look at how the animal got built in the first place. “One of the things that’s really important is how we pair up in order to make a baby. Other primates have lots of interesting options for mating scenarios and social systems, and we’ve gone for this really weird one, which is monogamy.”
The best explanation that generations of mainly male researchers could come up with for that was that it was to stop infanticide – male monkeys killing babies that weren’t theirs. Hassett begs to differ. “If you think a male monkey understands the concept of paternity, when there are a lot of humans who are iffy on the subject …”
Instead, she believes, pair bonding is practised by species that need extra investment in their babies in the form of another pair of helping hands.
“We’ve got these kids, and they’re weird. They’re super-demanding, they’re useless at birth. They need all the help we can give. And we’ve actually adapted ourselves to give them an insane amount of help – more than any other species on the planet.”
We are also the only species that agonises about the best way to bring up our young. The others just do it. Yet we’ve been getting it right for so long, so why do we still worry?
Hassett believes it is because we know that social changes we make will have an impact. The evidence is there in our teeth.
“We have changed our diets. We were grinding rough foods every day, in and out. [Then] we invented cooking, and carbohydrates, and bread. Fifteen thousand years ago, most people never had crooked teeth, they had much wider jaws and larger faces. Those were all products of the chewing regime that our faces had to go through. And now we’re stuck with having to have wisdom tooth extractions and braces.”
It’s one example of how social and cultural decisions can alter the environment we live in and how we may change as a result. “Maybe that anxiety is there for a reason, because we know that those decisions might change what kind of babies we have in the future.”
“Mummy wars”
It’s all very fascinating, but how does it help a frazzled parent deal with a wriggling, caterwauling lump at 3am?
For one thing, says Hassett, the history of childhood shows that children have survived various approaches to their care. That is why we are still here.
She heaps scorn on the ever-changing enthusiasms du jour, such as paleo-parenting, based on misconceptions about our evolutionary past.
“That’s not science. There’s no one true way. We are pretty adaptable babies. When it comes to what people call the ‘mummy wars’ – [for example, attachment parenting] whether you have to carry the baby all the time, whether you better give up your job and never try to see your friends for coffee – that’s just wrong. All of these things have a subtle message: that there’s a proper human way to do it, and if you don’t do that, then you’re messing up. It’s not really true – there’s a bunch of human ways to do it that have existed across time, across geography. And your society is going to determine what that is.”
Babies, it can be asserted with confidence, need feeding, cleaning and attention, no matter where or when they are born.
“But even if you look at different types of primates, there are very different types of caring and feeding. For our species, we can say they probably need milk. But we are very clever and have invented milk substitutes. We know that babies in the past didn’t necessarily have that option. So they had to either go to another woman or they didn’t survive. We have overcome this hurdle.”
According to researcher Katie Hinde, quoted by Hassett in an aside typical of the “well I never knew that” gems dotted throughout the book, the closest milk to human milk elsewhere in the animal kingdom is zebra milk.
But for all her counter-intuitive views in other respects, Hassett doesn’t think zebra milk could be an acceptable substitute for human babies – not quite enough protein, apparently.
Long childhoods
Pair bonding and its benefits have allowed us to stretch out our childhoods. We have longer gaps than other species between each of our life milestones – birth to the end of breastfeeding to independent feeding and puberty.
“And then we’ve got this adolescence that can go to 40, if you’re not careful.”
We have made good use of these longer time frames: “I think we can look at this extended childhood as the training we need to get along in today’s society.
“Our societies ask us for a huge amount of specialised training and a lot of that takes time.”
Is she saying that the longer we remain children the better, because we will learn more? Is this what has put our species at the top of the food chain?
Hassett thinks this may be so and that for evidence we need look no further than our old friendly competitors, the Neanderthals. If you are reading this, you are a member of the species that won that contest, and Hassett has a theory about why. The dental evidence suggests that they reached life milestones earlier than we do.
“One of the arguments has been: did we do better, because we let our children grow a little more slowly? One of the great things about letting children grow slowly is that if nutrition and food are not totally abundant, they have a bit longer to do catch-up growth. That longer amount of time growing up might have given us that much more advantage.”
The thirty-somethings
We talk disapprovingly of people who “never grow up”. Parents of thirty-somethings worry they will never get their homes to themselves. “He’s just a big kid” is not usually meant as a compliment, and today’s young people are mocked for their extended adolescence, but Hassett doesn’t necessarily have a problem with that.
“I wonder how universal the sentiment is that once you’re an adult, the responsibilities are such that you can never really be free and easy,” as we think of children being. She speculates this could be socially determined and free and easy adults are a real possibility.
Extended childhoods allow more time for play, which is crucial for learning and social development. This fact can be extrapolated out to an argument around the importance of ongoing education.
Historically, childhood would often finish at 10, at which point you were off down the mine. Today it can finish at 30, when people complete their degrees and stop learning and forming the social bonds that might last longer than the lessons they got from lectures.
Hassett is all for a later end point. If long childhoods are good, maybe longer childhoods would be even better.
“We always look for the economic output and the measurable outcome. ‘Oh you’ve got a degree; now you can go off and get that well-paid job.’ But we don’t prioritise all of that social time [at university, for example], which is when people are figuring out who they are, who their friends are going to be, the networks that are going to see them through the next couple of years of their life.”
The long-term view that Hassett’s work requires her to take informs her thinking about the world she lives in.
“I think we have a real problem with short-term thinking. Our political cycles reward this. It’s always been strange to me, as someone who considers time in the millennia.
“I think if people had more of an anthropological understanding of our species – why we do the things we do – there’d be a lot less anxiety about things like parenting and there’d be a lot more thought about the kind of investment we make in the future.”
Social benefits
We used to say the kind of training you got if you weren’t on duty down the mine was needed by some children, but not others. “If you were poor, you didn’t go to school; if you were a girl, you didn’t go to school. It’s still true in parts of the world,” notes Hassett.
A century ago, childhood effectively ended at the age of 12.
“My grandma finished school at 16, and that was a real achievement for her generation, her class and her background. I finished at 31 – that’s 18 years of society, and particularly the [UK’s] Student Loans Company, investing in me. But if you aren’t going to go into higher education, why don’t we have a social option for investing in children?”
In other words, one of the conclusions Hassett’s research has led her to is that the extended “play” period of learning could take the form of something other than tertiary education. You should not need to be, say, a trainee rocket scientist in order to have those advantages.
“Kids need to learn to socialise and build networks. What we’re doing with this extended childhood is making these social connections and setting our children up so they’re going to be able to succeed.”
It doesn’t have to mean university “but we either have to find a way to do that for all children or accept that we don’t want to”.
Hassett wrote Growing Up Human when she was pregnant with her first child, who is now 2. She is giving this interview five days before the scheduled delivery of her second. “So I’m about to find out why it is that humans normally space babies four years apart.”
And, yes, personal experience affected the book, which is a great read and definitely does not hew to standard academic publishing guidelines.
How to be a parent
Hassett wrote the book “because I’m a scientist, and I study humans. And I wanted very much to know why this whole process [of raising children] was such a faff. I wanted to know what actual experts said about raising children around the globe and in different ethnographic practices. And I wanted to know what to expect. So for me, it was almost aimed at parents more than my future undergraduates.”
She hoped that in the process she would find out everything she needed to know about parenting: “All this stuff like, what should I be feeding them? Do I have to breastfeed? I thought that was all going to be really super interesting and it turns out the whole pregnancy thing is like: Oh, God, it’s tedious. And it’s long. It’s not the slap-in-the-face event that it is at the end.”
Conceiving through IVF added another layer of complication. “I was very interested in the research about why human pregnancies are so difficult. What factors affect how you even get a baby in the first place.
“And then, of course, once I got pregnant, it was very much about: how do you get through this? What’s going on? For me, it was trying to explain my own condition.”
She’s done that and, in the process, she’s helped to explain the most common condition of all – the human condition.
Trowel play
In tandem with her academic work, Hassett, along with three colleagues, runs trowelblazers.com, a site devoted to highlighting the contributions of women in the ‘digging’ sciences (archaeology, geology and palaeontology), and to activities aimed at encouraging participation, especially from under-represented minorities.
“We are women who got together on the internet, sniping about how women’s contributions are never recognised,” says Hassett. “We all had stories about women in our fields who’d done amazing things, so we started collecting them. We expected to go for about four weeks, and that was about 10 years ago.”
Here you will learn about the likes of Miss Etheldred Benett, born in 1776 and probably the first female geologist, or Pornnatcha “Jo” Sankhaprasit, who made history by becoming Thailand’s first female underwater archaeologist.
“They may or may not have contributed exactly in the way that we think is appropriate, because they weren’t allowed to do university degrees or anything like that.”
One aim of the site is to counter “stereotype threat”, which, Hassett says, “is applied to a lot of people in situations where they’re not explicitly made to feel uncomfortable or unwelcome but they can see that they are not represented in the main group.
“Stereotype threat is an insidious block to people of colour, women, LGBTQ. If they don’t see themselves represented in science, it becomes that much harder.”
Submissions are welcome. “We usually get friends and family of various women who were doing pioneering things going, ‘Oh, well, you know, actually, my Aunty Joan went and did this.’”
Growing Up Human: The evolution of childhood by Brenna Hassett, Bloomsbury, $49.50.