Here’s something to think about: we runners might be engaging in one of the oldest forms of scientific reasoning on Earth. I don’t mean this metaphorically or poetically. Literally, that’s what I concluded from a paper published last week (see the TL;DR). I couldn’t stop thinking about it (no pun), so I dug a bit deeper. Running, as it shaped human evolution, wasn’t a mere physical activity. It was a cognitive bootcamp; a lesson in uncertainty, inference, updating hypotheses on the fly, and much more. We weren’t just chasing some animal, we were solving complex problems.

We tend to split the body and brain: the body runs, the brain thinks, and rarely the twain shall meet. In evolutionary time, the body was the brain’s first lab, esp. when it was tracking something, across 20 kms of brushland, on foot, in the cold, with no gels, and no guarantee of dinner. Running here, is not a break from thinking, it is thinking; sweaty, persistent, embodied thinking.

So when someone tells me “running is a distraction” or a break, I think: no, it’s not a break from thinking, it’s a way into it. Not running away, but running into clarity and imagination. This is a legacy worth investigating and remembering. Even if your version of prey these days is a finish line or just a little bit of peace.


Persistence hunting as proto-scientific thinking
What did that actually look like, on the ground? Let’s go back about 2 mln. years, and start with the chase, the original moving problem set. A lanky, upright primate (Homo erectus) squinting at a broken twig, a shallow hoofprint, fresh broken grass, the direction of a breeze. There’s just the open savannah and a faint hunch that something delicious was here.

The beginning of persistence hunting: the utterly human strategy of chasing prey not with speed, but endurance and reasoning. We run the animal to exhaustion. First, we have to find it. That meant thinking like it. What path would it take? Would it veer toward water? Is this poop warm or sunbaked? The act of tracking, sometimes for days, demanded something remarkable: the ability to form a hypothesis, act on it, receive new information, and revise theory on the move. In other words: Bayesian inference.

Psychologist David Geary calls this folk science, a proto-cognitive modeling that functions like math. Obviously, we weren’t crunching probabilities, but we were living inside uncertainty loops. We had to make probabilistic bets using indirect evidence. That’s cognition, and it requires:
1. A working memory: hold onto where the trail was; what you saw 10 min. ago.
2. Cognitive flexibility: switch theories when the trail disappears, or signs contradict each other.
3. Spatial reasoning: mentally simulate where an animal might be based on where it was.

That’s the backbone of executive function. The same stuff we use to solve puzzles, plan trips, navigate new trails, convince your partner to go to Chamonix next summer. If we’re honest, persistence hunting is a not a great business model: it’s slow and it fails often. The only reason it works is because humans are weirdly good at tolerating ambiguity while in motion. Our nervous systems are built to run the experiment even when we’re not sure what the answer is.

As such, tracking relied on systematic trial-and-error embedded in the body. We form a theory, we move with it, we get feedback, we keep going. In this sense, running was cognition. The body didn’t just carry the brain, it conducted experiments, each stride, we learned to think with our feet.


Transient hypofrontality and the flow state
It wasn’t just cognitive horsepower that kept early humans on track. It was also what our minds let go of. Sometimes, the smartest thing a brain can do, is quiet down. You likely experienced a moment on a long trail run, somewhere, sometime, when your mind goes quiet…. The internal chatter lowers its volume. You’re not calculating dinner plans, or revisiting that awkward email. You’re there, breathing in rhythm, nothing to solve, nowhere else to be. This is called transient hypofrontality.

The term comes from the neuroscientist Arne Dietrich, to explain a weird phenomenon: why repetitive physical activities, like distance running, or like drumming, can induce states of calm, euphoria, as well as amplify intuition, insight, and idea generation. Despite being hard. During prolonged aerobic effort, the brain redirects blood and energy away from its most metabolically expensive region, the prefrontal cortex. The part of your brain responsible for executive control: long-term planning, reasoning, social inhibition, that monologue narrating your existence. You need it to write a thesis or behave at a party. You don’t need it to follow a trail for hours straight. So the brain, in its energy-conserving way, dials it down temporarily.

When the prefrontal cortex chills out, other things come online. According to Dietrich and others, that downshift in frontal lobe activity allows more spontaneous associations between brain regions, esp. those linked to motor control and memory. This means that in the middle of a long run, while your “rational” brain is offline, you’re actually more fluid, zen, creative, and often more emotionally grounded. A 2019 review by Harris et al. connected transient hypofrontality to peak creative performance in athletes and artists. If you’ve ever found yourself solving a stubborn life problem during a run, or composing an imaginary apology speech to your boss with poetic brilliance… you’re running with less frontal oversight.

Embodied cognition is the theory that our cognitive processes are deeply shaped by our bodily form, motion, and interaction with the physical world. The way we move reflects what we know and creates what we know. In 1999 Smith and Gasser showed that movement-based learning in infants is a direct predictor of future cognitive flexibility. The body is teaching the brain how to think.

This doesn’t stop in infancy. When we gesture while talking, we’re offloading mental processing. When we pace to solve a problem, it’s a feedback loop. When we run for hours, making micro-adjustments, our bodies are not distracting us. They’re helping us understand it. The act of running through a landscape is a structure of thought.

Running is a form of embodied hypothesis-testing, sensory integration, perceptual awareness, and can results in that uncanny clarity we speak of: the thought you didn’t know you were working on resolving itself in silence. This might explain why so many ideas have been born on the run. The neural networks we use to imagine and navigate are often the same. We simulate both terrain and emotion using overlapping brain regions.

But why would the brain evolve this pattern? Because staying calm under pressure was adaptive. Think about it: you’re six hours into a tracking mission. You haven’t eaten. You’re sweating buckets. Your prey is elusive. If you were overthinking, you’d crack. You’d get anxious. You’d ruminate. You’d give up and go forage berries instead. But if your brain could suspend complex worry while maintaining sensory alertness and emotional balance, you could keep going and going.

The hypofrontal brain was dialed in. Research from Raichlen et al. (2012), found that aerobic activity activates a broad network of brain regions tied to affect regulation and decision-making, without necessarily engaging conscious control. It’s what psychologist Mihaly Csikszentmihalyi famously called flow: deep immersion without self-consciousness (never knew how to pronounce his name). In evolutionary terms, that might have been the secret weapon, not brute strength or pure logic, but a form of presence.

Turns out, this comes with its own reward system. If transient hypofrontality explains the how, the runner’s high may explain the why, why we keep going, even when logic says stop. This “runner’s high” was for decades treated like Bigfoot: reported and poorly understood, possibly mythical (possibly real). Science caught up, it turns out the magic is biochemical.

Let’s get more nerdy. During sustained aerobic effort, especially at moderate intensities, the body releases a potent mix of neurochemicals, including:
– Endocannabinoids: the body’s natural cannabis-like molecules, that can induce calm, euphoria, pain relief, a sense of being in the moment.
– Dopamine: involved in motivation, reward, motor control, makes you want to keep going.
– Serotonin: regulates mood and contributes to feelings of well-being, bonding, and patience.

Raichlen et al. found that both humans and cursorial animals, like dogs, experience endocannabinoid surges during endurance exercise, whereas non-running mammals do not. Evolution equipped some with a built-in high to reward movement. So when you hear someone say running is their therapy? When people describe trail time as sacred or mind-clearing? That’s probably neurophysiology: a brain designed by evolution to go quiet when the body goes long.

These chemicals don’t just make you feel good. They may help you learn better during and after endurance efforts. A 2021 study found that aerobic exercise can enhance hippocampal neurogenesis and long-term memory consolidation. Translation: movement may help encode the very experiences it rewards. That means the high is a payoff and a signal. A tag saying: this was worth remembering. This trail, this strategy, this pace and effort and ground: don’t forget it, come back, and try again.

Runner’s high might not just be a frivolous side-effect, not just your body throwing a party because you burned a 1000 calories. It’s ancient strategy. It’s the feeling that kept our ancestors moving, long after the antelope stopped seeming like a good idea. A drip-feed of reward for a brain and body that had to believe: the next mile is worth it.


The cognitive tradeoff hypothesis
At some point our ancestors stood up. A weird move, evolutionarily speaking. Bipedalism is awkward, imbalanced, slow, it makes childbirth complicated (I’ve heard). It requires a massive reconfiguration of the spine, pelvis, inner ear, among others, to keep us from faceplanting. But it came with a bonus: two free hands, and everything else: tool use, gestural communication, food transport, fire maintenance, and maybe even conscious intention. That’s the tradeoff.

This idea is known as the Cognitive Tradeoff Hypothesis, proposed by neuroanthropologist Dean Falk and later developed by researchers like Dietrich Stout and William Hopkins. The basic premise is: as our species evolved to walk upright, we traded away raw physicality (climbing, brachiation, sheer ape-like strength) for manipulation, communication, cooperation. A 2016 article found that the evolution of the parietal cortex, key to hand-eye coordination and spatial reasoning, was tightly linked to bipedalism and tool use. In other words, once we stood up, we had to get smarter to survive.

Running doesn’t seem like a cognitive act, but it requires a highly tuned system of anticipatory balance, proprioception, and inter-limb coordination. Your body is constantly predicting what the terrain does next and adjusting milliseconds in advance. This predictive modeling is managed largely by the cerebellum and parietal lobe, both of which saw significant evolutionary expansion in humans. And those areas support mental simulation, spatial planning, and even arithmetic.

According to research by Gallivan et al. (2013), the motor system is predictive; moving through space trains the brain to model futures. That’s a powerful advantage. As running bodies evolved to move better, more fluidly, upright, rhythmically, the brain piggybacked on that structure. Movement created new cognitive real estate.

There’s another piece to this puzzle. Freeing hands also was about expression; as mentioned, gestural communication is considered by many linguists to be a precursor to spoken language. With gestures, you have shared attention. With that, you have intersubjectivity: the awareness that others have minds, too. All of this may have begun with the body shifting from four points to two; movement became signal, tools became ideas. Running, then, wasn’t just about chasing prey faster, but about reshaping the scaffolding of cognition. 

Bipedalism gave us the platform. Endurance gave us feedback. Cooperation gave us meaning. Anthropologist Terrence Deacon calls this co-evolutionary bootstrapping: feedback loops between brain, body, and culture that slowly ratchet each upward. You move differently, so you think differently, so you act differently, and so on. The way we moved shaped the form of our minds. That form was recursive, experimental, deeply social; like running with others on an unfamiliar trail.

Still, no one watches a human run and says, “Ah, poetry in motion.” We are not the most beautiful runners in the animal kingdom. We flail, sweat, redline easily. But biomechanically? We’re beautiful freaks. Compared to our primate cousins, humans have:

– Long, spring-loaded Achilles tendons that act like rubber bands to store and release energy;
– Arched feet that work as built-in shock absorbers and propulsion systems;
– A strong nuchal ligament that stabilizes the head while running, also found in horses, dogs;
– Short toes for push-off efficiency and reduced injury risk during repeated impact;
– Large glutes to stabilize the trunk and hips during forward motion;
– A broad, counter-rotating shoulder girdle that balances leg swing with opposite arm swing.

All of this was laid out in Bramble and Lieberman’s paper, where they coined the term “endurance running hypothesis.” We evolved a suite of traits specifically for long-distance running. Traits that make no sense for climbing, sprinting, or even walking. Chimps, our closest relatives, are terrible runners. Get them on a smooth track for 30 meters, and they’re floundering. Why? Because their evolutionary path favored verticality and bursts of strength.

Ours? Horizontal persistence. We went from forest to savannah. From crouching to upright. Fossils show the anatomical signatures of this transition: narrower waists, longer legs, shorter arms, bigger semicircular canals (for balance). The body remodeling itself for endurance and shaping not just how we move, but how we perceive the world. It changed our relationship to space, direction, fatigue, pacing, time, et cetera.


Social cognition around the fire and on the trail
If you’ve ever finished a group run and immediately launched into a debrief: “What happened to John on the second climb?” “That sketchy downhill almost ended me!” “I think we were being stalked by a moose or a squirrel?” You are doing something ancient. There’s a theory: humans didn’t ran together so we could understand each other. Then we told stories about it. It’s built into our neural hardware.

Robin Dunbar, an evolutionary psychologist, proposed in his Social Brain Hypothesis. As our social groups got larger, our brains had to evolve to keep up. Tracking alliances, remembering relationships, inferring intent, all of this is cognitively expensive. It’s especially expensive when you’re trying to do it while moving. Research links neocortex size to group size across primate species. Humans came out on top because we’re better at keeping tabs on each other. Social cognition is our superpower.

Imagine a group of early humans persistence hunting. Tracking is noisy business. We need to coordinate who’s flanking left, who’s circling the ridge, who spotted scat. We’re doing all this while running. What’s required?
– Shared attention: the ability to focus on the same external cue;
– Joint intention: moving toward a shared goal;
– Theory of mind: guessing what others know, want, feel, or plan to do next.

That’s the early scaffolding of language. Tomasello et al. (2005) argue that cooperation is the root of human cognition. Our ability to collaborate toward uncertain goals, and talk about it later, is what differentiates us from our cleverest primate cousins. That collaboration had to begin in motion, but the trail was the first classroom.

Now add fire to the mix. After the hunt comes rest. The bodies are tired, but the minds? Buzzing. What happened out there? Who saw what? What near-miss turned into a victory? This is when language begins to turn into coordination and narrative. Polly Wiessner’s famous work among the Ju/’hoansi (!Kung) foragers showed that firelit conversations were overwhelmingly social and fictional: logistics, stories, jokes, myths. Around the fire, humans do not simply exchange information, they imagine.

What do you imagine after a long run? High on endorphins, you relive it, dramatize it, you analyze it. Running together gave us shared experiences; telling stories gave us shared meaning. “Do you remember when the antelope turned east and we split up, and I thought you’d lost the trail but then…” A post-run recap. A proto-podcast. A verbal map of movement and meaning. Runners became storytellers, and the storytellers became us. And I am now telling running stories.


Thermoregulation and the rise of the sweaty thinker
While some can’t stand it, dripping sweat might be the most human thing you can do. Since we’re not the fastest animals, we have to be the most stubborn movers in heat. Why? We sweat. Not just a little, not just in pits or other dark cracks. I mean full-body, pore-drenched, salt crusted and cascading sweat. Humans have somewhere ~2-4 million eccrine sweat glands, covering nearly every inch of our skin. Most mammals cool themselves by panting, which works, unless you’re running in the heat, mouth closed, trying to breathe and move at the same time.

Daniel Lieberman and Dennis Bramble outlined how humans evolved to become heat dump champions. Unlike other mammals, we can cool while moving, thanks to sweating, upright posture (less sun exposure), economy, and minimal body hair. That means our ancestors chased prey by out-heating them. At a slow, steady burn while the antelope overheated and collapsed. Persistence hunting was about thermodynamics, and you probably read this all in Born to Run.

Here’s the twist though: this isn’t just a physical edge. It’s cognitive, too. The brain is one of our most temperature-sensitive organs. When it overheats, it doesn’t shut down nicely, it glitches, and your coordination drops, attention frays, ultimately, your judgement falters. A study by Nybo et al. found that core temperature of +40°C can impair cognitive performance by 20–30%, especially in tasks requiring working memory and executive control. Being able to cool ourselves was a way to keep thinking under pressure.

Cool brains make better decisions. Which makes ultra running an act of system-level intelligence. The slow, integrated genius of body and brain working together to manage stress, time, energy in a hostile environment. Our ancestors won because they could keep their head cool, literally, while everything else around them was burning up.

Evolution didn’t select for peak output. Evolution selected for sustainable output. What mattered was how well you could regulate energy over long durations in unpredictable conditions. This applies to movement, sure, and to cognition. The brain accounts for about 20% of resting metabolic expenditure, even though it’s only about 2% of your body weight. That’s a steep price to pay. So it had to be worth it, and it had to be managed.

Running in the heat may have been one of the best training grounds for that kind of systemic coordination. To survive, you had to know how to pace, to think ahead, to sense the rising edge of danger, not just in the herd ahead, but in your own rising temperature, and to endure meant to tune yourself.

Conclusion
So if you’ve ever felt like your body wasn’t built to run, consider the evidence. You’re not broken. You’re not an imposter. You are the descendant of a strange, stubborn, highly sweaty lineage of persistence specialists. Biomechanical weirdos and anatomical rebels. The original ultrarunners.

We weren’t just born to run, but born into running as a way of knowing. So what does it mean, that we are the original ultrarunners? It means that endurance isn’t something we train for, endurance is something we descended from. Beneath our race plans, watches, foam rollers and finish line buckles lies a truth: we are the outcome of millions of small, sweaty experiments, in staying with effort and navigating the uncertain. In moving toward something we couldn’t yet see.

It means that running isn’t a modern convenience or recreational luxury. It’s a form of ancient literacy. A way of reading the land, body, mind, and each other. A way of knowing through motion. Of solving problems with logic and breath. Of being intelligent not in spite of effort, but because of it.

It means we carry a memory in our movement. Every time we run, we rehearse the same systems our ancestors used to survive: thermoregulation, spatial reasoning, sensory integration, joint attention. For thinkers, it offers a provocation: What if the answers you’re looking for don’t come from sitting still, and thinking isn’t something you do, but something you enter? For runners, it offers permission, to stop measuring every run in metrics. And feel what it means to persist rather than perform. To notice what emerges when the body leads and the mind quiets. For all of us, it offers a reminder: we didn’t think our way into being: we ran. We ran together. Through that effort, we became.