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Thursday, January 26, 2023

Review: Growing up Human

 Growing Up Human is written by an archaeologist. The question behind the book is to ask why childhood takes so long for humans, and how the various pieces of it comes together. The early part of the book is fairly straightforward and no doubt you've heard about how puberty onset is affected by body fat. The details are interesting:

A study carried out by Taipei Medical University researchers found that for every extra gram of animal protein eaten a day, the age of a girl’s first period moved forward two months. This is something of a cycle, it seems, as mothers who hit puberty at an earlier age go on to have bigger children – and they are more likely themselves to have an earlier puberty. Somewhere in us is an insistent little voice telling us to accrue fat – so we can have more babies...Not only do we have critical levels of body fat for reproduction, we need much, much more fat than other primates. Our female rhesus macaques from the lab hover between 8–18 per cent body fat; human females struggle to reproduce with less than 17 per cent. (kindle loc 1054-1064)

There's quite a bit of section devoted to debunking the recent fad behind attachment parenting and all the baggage that goes with it, as well as an interesting factoid about how your teeth effectively have a scar in there which indicates your growth line:

 Being born is sufficiently traumatic that a baby’s body sort of stop-starts normal growth, and that stop-start shows up as a neonatal line, which is a scar through the inside of your teeth where all the little cells had their moment of existential panic. It exists in all of your kiddie teeth and even in ones you have as an adult – the first big chunky adult chewing tooth that comes in was actually forming before birth, so you can see the scar there too. (kindle loc 1933)

Brenna Hassett has a good sense of humor, especially when it comes to methods of baby carriage and how the body wrapping fad doesn't mean much:

 Babies who have gone on to lead full and happy adult lives have been positioned strapped to chests, strapped to boards, hung on walls, in their parents’ arms, in slings or even – and this is a personal favourite – strapped to a board and then hung on a wall. (kindle loc 2068)

There's a huge long section about breast feeding. She debunks all the myths about how easy breast feeding is, and notes that even macaques have difficulty with it:

It’s not just humans – research has shown macaques struggling and many monkeys are just, quite frankly, very bad at babies the first time around. But the rather cruel thing is that human mothers are made to feel particularly bad about it.

Mammal milk maven Katie Hinde and anthropologist Brooke Scelza were able to discuss breastfeeding with Himba mothers from Namibia, where every single mother was able to breastfeed, something that certainly isn’t true in most Westernised cultures. The authors picked out two key factors that accounted for this remarkable success rate: the support of other mothers, and the absence of any taboo or stigma associated with breastfeeding in public. The things that inhibit breastfeeding in other societies – like working hours or social rules that prevent frequent feeding – are simply not a part of Himba life, along with the stress or even the guilt associated with not breastfeeding. (kindle loc 2458-2465)

 I loved the section about the invention of grandmothers:

While male strategies for reproduction appear to consist of both making a bloody mess and captivating primatologists, the more subtle strategies of the female have often been overlooked. Some strategies aren’t even that subtle. While the rest of our primate relatives have been merrily living out the spans dictated them by sensible models of energy in, energy out, and fitting appropriate periods of dependence and maturity into their size-appropriate life spans, humans have been busy developing a world-changing evolutionary female adaptation. Something so radical that it may be single-handedly responsible for our reproductive success and the subsequent overrunning of the planet; something so unlikely so as to be almost unbelievable: grandmas...An incredibly small number of animals live past the ability to reproduce – even our own species’ males maintain some generative capacity until nearly the end of their lives. Here are some animals with grandmothers that are done having babies: Orcas, short-finned pilot whales, us. Here are some animals without grandmothers: every other animal in the world.13 There are plenty of species where some animals don’t reproduce for whatever reason – perhaps they are not the dominant breeding pair, perhaps their mate has died – and continue to live without reproducing, but this is a very different thing to what we (and those whales) do, which is to live past our biological capacity to reproduce. (kindle loc 3001-3025)

There's even a casual debunking of why human males are slightly bigger than human females:

 We might actually be mistaking the reason human males are a teeny bit bigger; perhaps rather than trying to become an ultimate fighting/loving champion, males are just bigger because females are smaller. And females are just smaller because they stop growing earlier so they can put that energy into babies because, as you may have picked up from the theme of this book, babies are important. (kindle loc 3307)

 The last part of the book covers the effects of poverty on childhood:

if poverty was ever classed as a cause of death it would be number one in the world – in every country. Poor children are more likely to suffer preventable childhood diseases, more likely to have growth falter and to die before they reach adulthood. When it comes to childhood, there is just the one real difference to reckon. It is the one that was there between the snarky schoolboys of Aristophanes and the slaves that served them, and it is still present today, and that is the time we give it. (kindle loc 4818)

The book points out that the history of human evolution is our gradually increasing investment in childhood, and the recent trends in American society to de-emphasize education and childhood is an aberration.  I read this book and highlighted many sections of it. It's definitely worth reading.

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