The average human spends at least one quarter of their life growing up. In the careful calculus of the animal kingdom, this is patently ridiculous. Even most whales, the longest of the long-lived mammals, spend a mere 10 per cent or so of their time growing into leviathans (View Highlight)
the entire business of reproducing our species is absolutely off-the-charts weird. From our mating systems to maternal mortality to menopause, everything we do with our lives is a slap in the face to the received wisdom of the animal kingdom. (View Highlight)
The evolution of ‘dads’ – our casual word for the pair of helping hands that, in humans, fits a very broad range of people – may in fact be the only solution to the crisis that is the most important feature of human babies: they are off-the-scale demanding (View Highlight)
Our species’ pregnancies – and only our species’ pregnancies – have become life-threatening ordeals specifically to deal with the outrageous demands of our babies. Gestational diabetes and preeclampsia are conditions virtually unknown in the animal kingdom, but common killers of pregnant humans thanks to this subtle alteration. Babies grow to an enormous size and plumpness, and they’re so demanding that the resources in one body aren’t enough to sustain them. They emerge into the world with large brains and a hefty 15 per cent lard, but still unripe and unready. (View Highlight)
altricialidad evolución parto bebés homo_sapiens cita
This is what the anthropologist Sherwood Washburn in 1960 called the ‘obstetrical dilemma’: the dangerous trip down the birth canal is necessitated by our upright posture and the tight fit required by our big brains. This widely accepted theory provided functional explanations as to why male and female hips were different sizes and why our births are so risky (View Highlight)
Even accounting for differences in size, human babies are infants on the breast for a far shorter time than our closest relatives. Breastfeeding can go on for four to five years in chimpanzees and gorillas, and eight years or more in orangutans. Meanwhile, babies in most known human societies are fully weaned by the age of four, with a lot of agricultural societies past and present opting to stop around age two (View Highlight)
Our fat, big-brained offspring require a huge investment to support the amount of brain growth required in our babies’ first year, but they don’t – and can’t – get what they need to build the adult 1,200 g brain from milk alone. This is where those pair bonds come in handy. Suddenly there are two food-foragers (or chewers) to hand, which is convenient because we kick off our babies from the breast quick – but, once they’ve moved from infancy into childhood, there is yet another surprise: we let them stay there longer than any other species on the planet. (View Highlight)
homo_sapiens altricialidad desafío parentalidad parejas
Perhaps the most clear-cut definition describes childhood in terms of investment: it is the period when you are a net resource sink, when other people are still investing heavily in you. (View Highlight)
There is one more adaptation at play in the support of our needy offspring that should be accounted for: the utter (View Highlight)
unlikeliness that is a grandmother. Specifically, it is the almost unheard-of biological process of menopause, and the creation of a stage of life for half of our species where reproduction just stops. This is outrageous in evolutionary terms and it occurs only in humans (and a handful of whales). If the goal is to keep the species going, then calling time on reproduction sounds catastrophically counterintuitive, and, yet, here we are, awash in post-reproductive females (View Highlight)
ethnographic and sociological studies show us very clearly that grandparents are evolutionarily important: they are additional adults capable of investing in our needy kids. If you remove the need to invest in their own direct offspring, you create a fund of resources – whether it is foraged food, wisdom or just a pair of hands – that can be poured into their children’s children. (View Highlight)
A long childhood is our greatest evolutionary adaptation. It means that we have created needy offspring, and this has surprising knock-on effects in every single aspect of our lives, from our pair bonds to our dads to our boring genitals to our dangerous pregnancies and births and our fat-cheeked babies and even that unlikely creature, the grandmother. The amount of time and energy required to grow a human child, and to let it learn the things it needs to learn, is so great that we have stopped the clock: we have given ourselves longer to do it, and critically, made sure there are more and more investors ready to contribute to each of our fantastically expensive children. (View Highlight)