Bones’ Original Purpose May Have Been Storing Minerals

skeletal system under examination with "mineral warehouse" theory

By Jonny Lupsha, Wondrium Staff Writer

The human skeleton is the framework for the body—and much more. Our bones turn over 10% of their mineral content every year. This week on Wondrium Shorts, make no bones about it.

The adult human body hosts 206 bones from head to toe—er, toes. Functioning largely as the foundation or framework for the rest of the body, the skeletal system also connects to the muscles that we use to help us move, day and night. However, scientists believe that the skeleton once served as a warehouse for storing minerals.

How much do we know about human bones, aside from the fact that if we see one of our own with the naked eye, it’s probably a bad thing? In her video series How We Move: The Gross Anatomy of Motion, Dr. Elizabeth A. Murray, Professor of Biology at Mount St. Joseph University, outlines surprising facts about our skeletal system.

The Many Functions of Bones

Ask anyone what the skeleton does and they will likely mention that it supports our bodies and/or acts as the framework for our bodies. While true, that answer is only part of the picture. In reality, our skeletal system multitasks.

“Consider the rib cage, or the skull, and you’ll recognize the protective role that the bones provide for more vulnerable and soft internal organs,” Dr. Murray said. “You might also know that one type of our bone marrow, known as red marrow—found in flat bones and in the ends of long bones—is a source for the production of new blood cells that move out of the bones and into circulation.”

Additionally, due to the joints between them, bones work as levers in the systems that cause movement. In basic terms, according to Dr. Murray, muscles supply the force and joints serve as the fulcrums in these anatomical lever systems. And in addition to the red marrow that some bones store, yellow marrow can be found in the long bones of the body. Yellow marrow is a fatty energy reserve inside the hollow shafts of bones such as the femur.

And still, there are more services our bones provide.

What CAN’T Bones Do—Besides Bend Easily?

“Among the most important roles of the skeleton—and the one that many scientists believe was the original function of bone within the animal body—is to serve as an internal warehouse of minerals,” Dr. Murray said. “You probably know that calcium is the primary mineral in bone, but bone also houses phosphate salts, with phosphorus being another mineral important to good health.”

Also included in the bones are carbonates, sodium, magnesium, and potassium. Even trace amounts of iron, copper, zinc, manganese, fluoride, strontium, and boron are found in the skeleton. All of these are important in “various metabolic and enzymatic pathways,” according to Dr. Murray.

Just because our bones have all these salts and minerals in them, why do scientists believe that the original function of bones was specifically to store them?

“Let’s just consider calcium as one example: Calcium and phosphate salts crystallize and, together with other minerals, make bones hard and durable,” Dr. Murray said. “But calcium is also a required ingredient in the reactions that cause all of our muscle activity, including our heartbeat. Calcium is also necessary for the propagation of electrical signals in the nervous system, and also aids in the body’s chemical messaging with the release of hormones from glands.

“As if that weren’t enough, calcium is also necessary for normal blood clotting, so minor injuries don’t result in the loss of too much blood.”

In terms of evolution, it is a considerably effective way of keeping a supply of these minerals on hand, just in case they’re needed between meals, or as our bodies need them when we fail to ingest sufficient quantities.

This article is part of our “Deeper Dive” series where we examine the stories behind our Wondrium Shorts on YouTube.

Edited by Angela Shoemaker, Wondrium Daily