Mechanical Engineering in the Skeleton
Note: While the editor is out of town, we are bringing you readings of interest from creation books associated with CEH.
Wonders of the Immune System, by Dr Henry Richter
from Spacecraft Earth, a Guide for Passengers (CMI, 2017, ch. 2, “The Spacesuit: The Amazing Human Body,” pp. 42-44).
The elbow is a marvelous piece of mechanical design. It is an articulating joint between two bone structures that allows movement of the arm along two different axes (hinge movement and some rotation). An elbow is essential for people to be able to manipulate their surroundings. It’s just one example of the hundreds of joints in the human body. Fingers have three joints each. The wrists have gliding joints that allow motions in two dimensions, allowing the hand to move up and down or side to side. The shoulders have ball-and-socket joints. The legs have joints at the hips, knees, and ankles. Feet have dozens of joints; the bone structure of the foot is “a biomechanical masterpiece” one news report said.
The elbow is a ‘hinge joint’ that connects the humerus of the upper arm to the radius and ulna of the forearm. It actually consists of three joints in one. The humeroradial joint is a ‘ball and socket’ joint that complements the hinge-type humeroulnar joint. The bone ball is perfectly matched to the cavity of the socket. Cushioned with cartilage, it permits smooth, easy movement while being held in place in this captured position. Cartilage provides a smooth, very low friction surface between the ball and the socket. Then there is a gland, which secretes the perfect lubricant to the cartilage, thus ensuring low friction between the ball and the socket. Figure 1 shows the basic components.
We must wonder, again, how all these parts could have come together through a series of random mistakes (mutations). If they required numerous small, gradual changes one-by-one, then how did rudimentary bone joints function before all of the necessary features were in place and working in concert? How could a mutation creating a ball provide any fitness benefit before its matching socket arrived? A square ball and a square socket certainly wouldn’t work. If the first production of a ball at the end of the bone was not approximately spherical, then how could the joint move? If the joint didn’t move, it would be useless, and the survivability of the body would be very much in question. If the first product of an elbow were so crude as to not allow much movement, then how did that body survive and produce countless generations in order to let random chance produce a more perfect joint?
The elbow is not only able to bend like a hinge, but also to rotate in the upper radius-ulnar joint, rotating the hand with it. This requires an additional set of muscles, the radius bone fitting into the socket and controlling the ball at the end of the humerus bone. That’s amazing.
The same can be said for all the other articulating joints in the body. It is interesting to me that all of the joints are so similar in function and design. If an elbow came about through a long chain of random, gradual variations to individual elements, then how come our two elbows are identical, yet mirror images of each other? If one of them developed through a long series of spontaneous aberrations, it seems remarkable that an identical set of aberrations would have happened to the other elbow to create an identical design with the opposite orientation. Even if, (as evolutionists believe), these came about by master-switch genes far upstream of the details, why would these master switches create symmetry between left and right parts of the body?
Consider just one elbow. How did its development progress having to simultaneously produce a bone ball and matching socket, the cartilage just right to cushion movement, and the lubricating fluid to maintain the cartilage? Each is necessary for the proper working of the whole. If any one of these elements was missing or improperly shaped, that early organism would have had a very difficult time of movement and survival waiting for random chance, again through countless generations, to supply the missing cartilage, fluid or exact matching shape of the ball and socket.
That lubricating fluid, by the way, has been called “nature’s most effective grease.” The substance, called lubricin, is a protein with tiny “feet” that attach themselves to virtually any surface. The proteins assemble into a dense, carpet-like layer between the joints that cushions the bones as well as reducing friction as they slide past one another. Without this amazing substance, bones would wear out much faster and our movements would be painful and stiff. Instead, they allow us to operate like a ‘well-oiled machine’. Was the origin of this highly effective lubricant just one more accident of nature?
We do not see imperfect or missing forms around us now, except in rare circumstances—and those are usually caused by genetic defects. Yet genetic defects are supposed to be the raw material for improvement in living things! Genetic defects are overwhelmingly deleterious. Even if a beneficial mutation did arise, it would not add novel genetic information which is required for organisms to progress from simple to complex. Most likely, it would be useless (and quickly removed) if the matching parts had not arrived by another mistake in the same individual in a population.
The same series of questions can be asked about the dozens of other joints in our elbows, knees, hips, fingers, and toes. It is certainly interesting that all of them are identical in design but come in mirror-image pairs.
Similarly, think of the spine, with its capability to move up and down along most of its length. The spinal joints between vertebrae display a different design altogether. Being hollow, they provide a protective conduit for the nerves. It would be bad news if our nerves ran outside the protection of the spine! But protected inside, they allow signals to pass from the brain down the neck, through the vertebrae, and then throughout the body, all the way to the ends of the fingers and toes. It’s an absolutely marvelous piece of design engineering!