Living bone is moist and slightly springy. Pressure on a bone creates a small electric charge in it.
Bones love stress. They carry stress through you and into the ground. The greatest stresses develop on the surface of bones. That is where bones are hardest. The core of the bone carries little stress and can be almost hollow, like bamboo.
Archaeologists can tell from any bone fossil whether it belonged to an upright creature. Every single bone in you is shaped in some way by your uprightness.
Unless there is something unusual about you, every bone in you is either symmetrical around your vertical midline, or it is paired with an opposite bone on your other side.
Our limbs evolved from fish fins. Our hands and feet still show the fan shape of original fins. Our shoulder and hip joints can rotate: they are swivel joints inherited from lobe-fin fishes. Those fishes used their fins to swivel to help them hover in water currents.
The shoulder and pelvic girdles evolved to support our weight on land. The shoulder girdle attaches across the front. This leaves an animal's neck free in back so it can bend down to reach food. The pelvic girdle attaches firmly in back to carry propulsive force from the ground up into the spine.
The front of the spine is smooth and cushioned so it can transmit force through its length. The back of the spine is knobby and arched to make room for nerves, and also to give attachments for leverage to layers and layers of muscle. The front of the spine is more for support, the back is more for movement.
The ribs are spring-loaded and need only be released in order to move. Their movements lever against the spine.
The skull moves as a single unit to give the senses stable housing while the rest of the body moves. When the senses need to reorganize, the many suture joints of the skull can loosen slightly to allow that.
The tiny ossicle bones in the middle ear amplify sound about 20 times. The nocturnal mammals we got them from needed good hearing to give them time to chew their food. In reptiles these were jaw bones, used for hinging the mouth open wide to swallow food whole.
The little hyoid bone above your Adam's apple has no joints with other bones, and hangs freely suspended from your skull. Your voice hangs suspended from it.
Your sinuses are bone hollows that are mainly for resonating sound. All bones are carriers of sound.
The red blood cells that are your lifeblood are created in marrow in the core of your thickest bones,.
Bones can reshape in response to long-term changes in habits of movement.
A person's character is visible in their bones after they die.
©Erik Bendix, 2009
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