Grounded Titans: The Square-Cube Law and the Surprising Reason Ants Can't Fly
Ants can lift objects many times their weight due to the square-cube law, where strength scales differently than mass at small sizes. However, this incredible strength isn't the same as the ability to fly. Flight requires generating lift, a force that lifting another ant simply can't create.
We've all heard the astonishing fact: an ant can lift 10, 20, even 50 times its own body weight. If a human could do that, they'd be hoisting a small car over their head. This incredible feat of strength has led to a quirky thought experiment that pops up in online forums and late-night conversations: If two super-strong ants could lift each other, could they achieve flight? The answer, rooted in some fundamental principles of physics, is a resounding no. The story of ant strength is not one of magical muscles, but of simple, elegant scaling laws.
The Secret is in the Scaling: The Square-Cube Law
The key to understanding an ant's power lies in a concept called the square-cube law. First described by Galileo and later popularized in biology by J.B.S. Haldane in his 1926 essay "On Being the Right Size," this law governs the relationship between an object's size, its surface area, and its volume.
Here's how it works: As an object gets larger, its volume (and therefore its mass) increases by the cube of its scaling factor, while its surface area only increases by the square. Think of a simple cube. If you double its side length, its surface area becomes four times larger (2²), but its volume becomes eight times larger (2³). For a living creature, muscle strength is roughly proportional to its cross-sectional area, while its weight is proportional to its volume. This means that as an animal gets smaller, it has far less body mass to carry relative to its muscle strength. An ant isn't strong because its muscles are made of a super-material; it's strong because it's tiny.
"If you scale an ant up to the size of an elephant, it would collapse under its own weight. It wouldn't be able to do anything." - Robert Full, Biomechanist at the University of California, Berkeley.
This is why an elephant, for all its might, can't lift 10 times its own weight. Its massive volume has outpaced the cross-sectional area of its muscles and bones, which must be incredibly thick just to support its own body against gravity.
More Than Just Muscle: The Mighty Neck Joint
While the square-cube law provides the foundation for their strength, ants also have remarkable biological adaptations. Researchers at Ohio State University, curious about the mechanics of this strength, focused on a surprisingly crucial body part: the neck. Specifically, the soft tissue joint that connects the ant's head to its body.
Using a micro-CT scanner, they created a 3D model of the Allegheny mound ant's neck and discovered that the surface of the joint had a unique, bumpy texture. This micro-scale texturing increases the surface area and friction, allowing the joint to bear incredible loads without failing. In experiments, they found the joint could withstand pressures up to 5,000 times the ant’s own body weight before breaking. This remarkable piece of natural engineering is what allows an ant to carry a massive leaf or another insect back to its colony without losing its head—literally.
The Physics of Flight: Why Strength Isn't Lift
So, if they are so perfectly engineered for strength, why can't two ants collaborate to fly? This is where we must distinguish between lifting and flight. Lifting an object is about applying an upward force to counteract the downward pull of gravity. It's a static, one-dimensional action.
Flight, however, is a dynamic process that requires generating lift—an aerodynamic force that pushes an object upward. Birds, insects, and airplanes achieve this with wings. By moving a specially shaped wing (an airfoil) through the air, they create a pressure difference: lower pressure above the wing and higher pressure below it. This differential results in a net upward force. Simply put, you need to push air down to go up.
When one ant lifts another, it is merely supporting its weight. The two ants together become a single system. According to Newton's Third Law, the force Ant A exerts on Ant B is equal and opposite to the force Ant B (via gravity) exerts on Ant A. There is no external upward force being generated to overcome the combined weight of both ants. They are simply a static, two-ant stack, firmly planted on the ground. To fly, they would need wings and the powerful muscles to flap them, a completely different evolutionary toolkit than the one they use to be the world's strongest weightlifters.
The ant remains a titan of the terrestrial world, a testament to how the laws of physics shape life in ways both powerful and limiting. They can move mountains, one tiny grain at a time, but their strength will forever keep them grounded.