Human body
The femur is the longest and strongest bone in the body, and it is stronger than concrete by weight.
The thigh bone makes up about a quarter of a person's height. It routinely handles forces of several times body weight when you run or jump.
Why is this true?
Bone is a composite of hard mineral and flexible collagen, so it resists both crushing and bending. Because it is also alive, it repairs small cracks and thickens where it is stressed most.
More facts in this category
More about human body
Your own body is a reliable source of surprises. It replaces cells by the million every second, keeps bacteria that outnumber human cells, and runs sensory tricks that make the world feel smoother than the raw signal ever is. The facts collected here stick to mainstream physiology, avoid the wellness myths that circulate alongside them, and explain the underlying mechanism rather than just quoting a startling number.