Myth vs. Mind #8: Does Bigger Brain Size Mean Higher Intelligence?
It’s Not The Size That Matters. It’s What The Brain Does
For centuries, people have assumed that bigger brains equal higher intelligence. From comparing skulls to measuring head circumference, this myth has persisted in science, pop culture, and everyday conversation.
But here’s the twist: it’s not the size that matters; it’s what the brain does.
Other Psychology Myths Uncovered
I’ve always been fascinated by how we link physical appearance to mental ability. In mystery stories, the “genius detective” is often portrayed with an oversized forehead or striking head shape: a visual shorthand for brilliance. But when you look closer, the science of intelligence reveals a far more nuanced (and fascinating) picture.
Why Did This Spread So Easily?
The myth has deep historical roots:
Phrenology in the 19th century claimed you could measure bumps on the skull to predict traits like creativity or honesty. It was pseudoscience, but it shaped how people thought about intelligence.
Darwin’s era fascination with evolution fueled the idea that “bigger brain = more evolved.” Scientists compared species by brain size, assuming more volume automatically meant smarter.
Simplicity sells. Bigger equals better, so it’s an easy metaphor, and our minds love easy metaphors.
Personally, I do believe that part of the allure is how visible the myth feels. You can’t see neurons firing, but you can see a forehead. Often, body language, appearance, and physical cues are tied to intelligence in storytelling, even though science shows us the truth is deeper.
What Research Tells Us
When scientists really began studying intelligence beyond the skull-measuring days of phrenology, the picture got a lot more interesting and more complicated.
Brain-to-body ratio. Raw size means little without context. Whales and elephants have brains many times larger than ours. But when you consider body size, humans have a much higher brain-to-body ratio. It’s not just about mass; it’s about how much “brain power” is dedicated to cognition versus basic survival functions.
Cortical folding. One of the biggest predictors of intelligence is how “wrinkled” the cortex is. Those folds increase surface area without increasing size. It’s like packing more circuitry into the same space. Einstein’s brain, for example, was remarkable not in size but in increased asymmetry and how unusually folded his parietal lobe was (the region linked to spatial reasoning and math).
Connectivity and white matter. Think of white matter as the “wiring” between brain regions. High intelligence correlates strongly with how efficiently different areas communicate. It’s not about having more grey matter alone, but about how well the grey and white matter work together.
Plasticity. Perhaps the most important factor: the ability of the brain to rewire and adapt. Neuroplasticity allows us to learn languages, pick up new skills, recover from injury, and even change personality traits over time. Intelligence is dynamic: it grows and adapts with experience.
Genetics and environment. Genes set the stage, but the environment does the sculpting. Nutrition, education, stress, and relationships all influence how the brain develops and performs. Intelligence isn’t a fixed “size gift” at birth; it’s a lifelong collaboration between biology and experience.
In other words, it’s not the size of the brain that counts. It’s the design, the wiring, and the lifelong capacity to grow.
Everyday Examples
You don’t need a lab to see how misleading the brain-size myth is. Look at everyday life and nature:
The whale paradox. Sperm whales have the largest brains of any animal, up to 8 kg/ 18 pounds. Yet their intelligence serves specific ecological functions: deep-sea navigation, communication, and memory of migration paths. Useful, yes. Superior to humans? Not in abstract reasoning or creativity.
The small-but-brilliant student. We all knew classmates who didn’t “look the part” of the genius. No giant foreheads, no dramatic appearance. Yet they excelled in problem-solving, creativity, or empathy, because intelligence shows up in networks and behaviour, not skull size.
Childhood development. Babies don’t have giant brains, but their small brains undergo a breathtaking explosion of neural connections in the first years of life. Intelligence grows not from sheer size, but from synaptic pruning, reinforcement, and wiring.
Technology and learning. Think of people who dive into learning coding, painting, or a new language later in life. Their brain doesn’t “get bigger”; it builds new pathways. That adaptability is a truer marker of intelligence than mass.
These examples show that the myth doesn’t just fail in theory. It fails in practice. Every day, we see smaller, adaptive systems outperforming bigger ones.
Why This Matters
Believing that brain size equals intelligence isn’t just an innocent mistake; it has had (and still has) real-world consequences.
Education mindset. If intelligence were just about size, education wouldn’t matter. But neuroscience shows the opposite: learning, challenge, and environment can dramatically reshape the brain. Believing in the size myth discourages growth and effort.
Self-limiting beliefs. People may internalise myths and tell themselves, “I wasn’t born with a big brain, so I’ll never be smart.” That’s tragic, because intelligence isn’t fixed. It can expand with practice, curiosity, and persistence.
Behavioural misreadings. Linking appearance to intelligence fuels stereotypes. The “big head genius” trope persists in pop culture and even in subtle social judgments. In reality, intelligence is far better read in behaviour, adaptability, and communication than in body proportions.
Ultimately, this matters because it shapes how we treat others and ourselves. Understanding that intelligence is dynamic, relational, and rooted in behaviour helps us build reliable systems, healthier self-images, and richer opportunities for growth.
Final Thought
The myth that bigger brains mean higher intelligence persists because it’s simple, visual, and easy to tell in a story. But reality is far richer: intelligence is about wiring, efficiency, adaptability, and the dynamic ways our brains learn and grow.
As someone who studies behaviour, I like how this myth reveals the gap between what we think makes someone “smart” and what truly does. It’s not in the forehead wrinkles or skull size, but in the way we think, connect, and communicate.
If myths like this fascinate you, subscribe to join me as we dig deeper into psychology, behaviour, and the brain. Let’s keep unravelling the mysteries together.