Issue 6 | 31st December, 2022 | 6-9 minutes reading time
Heyo, and welcome to your fortnightly sporadic latest issue of Multitudes. I’m Shantanu Kishwar, your friendly curator of interesting trivia.
In July, I wrote about how our ability to learn was part of why humans thrived on Earth. Recap: as babies, humans are utterly dependent on caregivers for years. Many animals, meanwhile, become independent earlier in their lives. Elephant calves are able to walk within an hour of birth; babies can take up to 3 months just to hold their heads up. How did these babies, the diaper-dirtying and tantrum-throwing creatures that they are, ever grow up to rule the planet? Partly because, though we’re weaker than animals as infants, as a collective and in the long-run, our ability to adapt quickly to changing circumstances makes us stronger. They, meanwhile, adapt over the long arc of history through the slow process of natural selection.
Stuff I’ve learned since shows that this neat explanation is somewhat incomplete.
The bit about humans and learning seems to hold. It takes us a long time to grow into fully functional adults - I’m 26, have likely lived between a third and a quarter of my life, and still struggle to do so. This delayed entry to adulthood, though, pays off.
Dr. Alison Gopnik is a developmental psychologist who’s studied the childhood of different animals. She found a correlation between the length of an animal’s childhood and its abilities when fully developed. It’s why, she said, crows take up to two years to mature but, at the end of these two years, are capable of complex tasks. They make for interesting research subjects and have been featured on the cover of Science magazine. Chickens, meanwhile, have a childhood of only two months. They’re suited primarily to pecking at food and are more likely to star in a dish on Masterchef than the cover of Science.
For animals programmed to be good at just a few things, short childhoods work fine. But for animals to develop broad abilities, longer childhoods are necessary.
As humans living in modern societies, we’ve taken this to the extreme. It’s only around age 21, and after a decade and a half of formal education, that we’re expected to make our first foray into ‘adulthood’.
There are parallels to this in other areas of human development. In his amazing book, Range (which I wrote about last January), David Epstein wrote about generalisation versus specialisation. He saw that across fields, be it athletics, music, academics, or whatever else, people who dominated tended to be generalists, not specialists, early on in life. The likes of Roger Federer, for example, tried many different things before choosing one to specialise in; Federer himself played at least ten sports as a kid before settling on tennis.
In this sampling period (the equivalent of infancy), they fell behind others who specialised from the get-go. Once they found the right fit (emerging into adulthood), they tended to hit higher peaks than the early specialists. Again, a longer childhood/learning phase paid off later.
So that’s what I learnt which built on what I knew earlier. Now for where I was wrong.
In that same July newsletter, I also wrote that natural selection was extremely slow. I thought that only over millennia could animals adapt to changing conditions through favourable mutations. Turns out, climate change is proving otherwise.
You don’t need me to tell you that humans are changing the natural world at an alarming pace. Most animals can’t adapt and are perishing in what’s called “the Sixth Extinction.”
But the key word here is most - most animals can’t adapt, but some can. Climate change isn’t just accelerating extinction; it’s doing the same to natural selection.
Researchers in the Turks and Caicos Islands in 2017 found a distinct difference in lizard populations before and after hurricanes Irma and Maria. Lizards that survived the hurricanes tended to have larger toe-pads and shorter hind legs. When faced with hurricane-force winds, they could latch on to trees for long periods. This allowed them to survive and meant that their offspring would thrive. Those lizards who, before the hurricane, had long hind legs and small toe-pads couldn’t hold on for as long, perishing instead. Here, natural selection played out not over generations but a single season. If survival of the fittest was the rule of the game, hurricanes made more severe by climate change became an unwitting playground.
There’s a term for such high-speed natural selection - evolutionary rescue. The SciShow video below gives more examples, like that of the cliff swallow. Among these birds, specifically those that nested near busy roads, those with shorter wings were favoured by circumstance. They, unlike their long-winged companions, could manoeuvre faster in the face of oncoming traffic to avoid becoming roadkill.
Similarly, fish are getting smaller, living shorter lives and becoming sexually active at a younger age. This way, they are spared from human commercial fishing operations, which seek out larger fish. Basically, they’re living fast, doing the deed, and dying young so they don’t end up in a supermarket.
Mosquitos, snakes, butterflies, microbes, elephants, and likely many other species are doing the same to escape extinction. But, as much as this might seem like nature fighting back, it isn’t. Humans, unfortunately, are just too powerful. We’ve wiped out 60% of all animal populations in just the last 50 years and are on track to push half of all species into extinction by the end of this century. What evolutionary rescue can do is help us identify species less like to survive on their own and focus conservation efforts on them.
TL;DR? Humans succeeded at taking over the planet partly because of a slow start to life, and nature’s moving faster than ever to counter the effects of that success. The fact that I’m a human is also why I could learn about this in the first place. Neat, huh? (except for the part where we destroy the planet.)
Chances are you’ll be reading this around the New Year. I’m ending 2022 by watching John Green’s We’re Here Because We’re Here (linked below). It’s a mesmerising, heartfelt and (happy) tear-inducing adaptation of the Auld Lang Syne chapter from The Anthropocene Reviewed. Watching it left me feeling a little more human, and a little more kind; an embodiment of the optimism I nervously approach the New Year with. I can’t think of a better companion to prepare myself for the the grand-annual-blank-slate, and I’m grateful for its existence. If you can take 20 minutes out of your day to surrender yourself to this work of art, please do. It’ll be worth it.
Anyway, that’s it for this issue and this year. If you know something that either proves/disproves any of what I’ve written above, send it my way. I want to learn more, because I can, because I’m human.
Unlike 2021 and 2022, I won’t start 2023 off with a whole new newsletter (the relief). Instead, I’ll be sending an issue of Multitudes your way on the last Saturday of every month.
I hope you’ll stay a part of this little endeavour. Should you, for any reason, prefer not to, you can unsubscribe at the bottom of this mail. If you’d like to bring more people along for the ride, send this across to someone through the button above. If this is the first time you’ve come across this and you want to get these emails straight in your inbox, you can subscribe below.
Wherever you are, I hope you have a fun end to 2022, and a calm start to 2023. I’m looking forward to more reading, writing and, if my body holds itself together, running next year.
Take care,
Shantanu.