The idea that creatures—humans included—are governed by hardwired instincts is a comforting one. It suggests order, predictability, and perhaps even an excuse for that inexplicable urge to hoard snacks. But biology, as usual, refuses to play along neatly. Instead, we find that so-called “instincts” are often more like rough drafts, heavily edited by experience, environment, and even the ghostly hand of epigenetics. The myth of the unshakable instinct

Take parenting. The “maternal instinct” is often invoked as if it were a biological mandate, yet plenty of first-time mothers (and fathers) report feeling like they’re winging it. Turns out, they are. Primates, including humans, learn childcare by watching others. Even rats, those paragons of instinct, improve their mothering skills with practice. Meanwhile, in the insect world, honeybee larvae fed royal jelly become queens, while their pollen-fed siblings become workers—proof that even rigid caste systems are just a meal plan away from flexibility.

Aggression, another classic “instinct,” fares no better. Yes, males of many species spar for dominance, but isolate a rat pup from rowdy peers, and it won’t magically turn into a gladiator. Even sea turtles, those instinctive navigators, rely on Earth’s magnetic field like a GPS—hardly the stuff of immutable programming.

Nature’s improvisation

If instincts aren’t quite the fixed scripts we thought, what fills the gap? Enter developmental plasticity—the body’s ability to tweak its own blueprint based on the environment:

  • Bird song, long held up as innate, is actually a cover version. Young finches need to hear their species’ tunes during a critical window, or they’ll botch the performance. White-crowned sparrows take it further, shunning other birds’ songs like musical snobs.
  • Locusts switch from solitary to swarming modes when crowded, a transformation so dramatic it’s like a quiet librarian morphing into a festival hooligan—all triggered by serotonin.
  • Daphnia, tiny crustaceans with more survival tricks than a spy novel, grow defensive spines when they smell predators. Miss the cue, and they’ll skip the armour, proving that even “instinctive” defences are negotiable.

The memory of ancestors

Here’s where it gets eerie. Some plastic changes aren’t just personal—they’re inherited. Stickleback fish exposed to predators produce jumpier offspring, as if passing down a memo: “The world is scary.” Plants nibbled by herbivores arm their seedlings with pre-emptive bitterness. These epigenetic mechanisms—chemical tags on DNA that switch genes on or off—blur the line between learned and innate. Suddenly, Lamarck’s discredited idea of inherited experience doesn’t seem so silly.

Why instincts are overrated

The real kicker? Many “instincts” might just be canalised plasticity—traits that become predictable because the environment is. Beach mice’s camouflage, for instance, may have started as a flexible response to sand colour before evolution locked it in. Meanwhile, bird embryos learn their mother’s calls before hatching, making post-birth recognition less “instinct” and more “prenatal eavesdropping.”

Even the vaunted fixed action pattern—think baby birds gaping at red dots—falls apart under scrutiny. Herring gull chicks prefer realistic parent models, but slap a stick with a red blotch near them, and they’ll still beg. Is this instinct, or just a crude heuristic in a world where most red things are beaks?

Instincts are overachieving habits

In the end, instincts look less like destiny and more like deeply ingrained habits—shaped by genes, yes, but also by experience, environment, and the ghostly whispers of ancestors. So next time someone blames their snack-hoarding on “human instinct,” feel free to counter: “Actually, that’s just your epigenetics talking. And possibly your childhood.”

Instincts on the school run

Nowhere is the myth of hardwired behaviour more charmingly dismantled than in human society. If instincts were truly fixed, we’d expect all toddlers to share toys, all teenagers to rebel in precisely the same way, and all adults to know how to merge lanes without passive aggression. Instead, we find cultural patchworks: children taught to be silent in some homes, boisterous in others; greetings ranging from firm handshakes to nose rubs; and entire nations who queue like saints beside those who treat bus stops as a contact sport.

Consider gender roles. The notion that boys are ‘naturally’ boisterous and girls inherently nurturing doesn’t hold up when you examine societies where those roles are flipped—or simply irrelevant. In Sweden, paternal leave is the norm. In the Aka people of Central Africa, men are baby-wearing champions. Biology might provide a starter kit, but it’s society that decides which parts are assembled—and whether the instructions are followed.

Culture as co-author

Culture, in this light, becomes a kind of environmental pressure—shaping not only behaviour but even biology. Studies have shown that literacy can affect how brains are wired. Musical training thickens specific brain regions. Stress alters hormonal profiles. And then there’s language: tonal languages like Mandarin demand different neural real estate than English or Finnish. None of this is preordained. It’s life experience, scaffolded by a very plastic brain.

So while evolutionary psychologists might wax lyrical about meat-gathering instincts, the truth is likely messier. We’re improvisers, borrowing from instinct, culture, memory, and a hefty dose of trial and error. Think less “genetic puppet” and more “crowdsourced jazz”.

Resources and further reading