Human Life—A Precious Gift pt.2
APPRECIATE YOUR SPECIAL GIFTS
THE human body is outstandingly versatile. No animal has the sheer range of abilities that we humans do. One reason for our versatility is our upright stance, which not only expands our area of vision but also frees our arms and hands for any number of tasks. Imagine how our activities would be curtailed if we had to walk on all fours!
Another asset is our highly sophisticated sensory system, which will be the focus of this article. The system includes the hands, the ears, the eyes and, of course, our exceptional brain. Let’s look at these individually.
The Human Hand
Our hands are beautiful instruments of amazing precision. With them we can thread a needle or swing an ax, paint a portrait or play the piano. Our hands are also highly sensitive. Even a brief touch may reveal whether a substance is fur, paper, skin, metal, water, or wood. Yes, our hands are much more than implements for grasping and manipulation. They are also a source of knowledge about our world. And they are a means of conveying warmth and affection.
Why is the human hand so adept, so expressive, so sensitive, and so versatile? The reasons are many. Consider four.
- Our two hands have a total of more than 50 bones, about a quarter of all the bones in the body. The intricate assembly of the parts of the hand—the bones, the joints, the ligaments—gives the human hand extraordinary flexibility.
- The hand has an opposable thumb mounted on a saddle joint, an ingenious configuration of two saddle-shaped surfaces at right angles to each other. This joint, along with the associated muscles and other tissues, gives the thumb amazing flexibility and strength.
- Three sets of muscles control the hand. The two most powerful sets—the extensors and the flexors—are in the forearm and operate the fingers by means of tendons. How bulky and unwieldy the hand would be if these muscles were located in it! The third set, much smaller, which does lie within the hand, gives the fingers precision of movement.
- Your fingers are, in effect, living sensors—the fingertips having about 2,500 receptors in just one sixth of a square inch (1 sq cm). Moreover, the receptors are varied, each kind having its own function, enabling you to feel texture, temperature, wetness, vibration, pressure, and pain. As a result, the human finger is the most sensitive touch sensor known.
The Human Ear
Although some animals can hear sound frequencies beyond the range of human hearing, the combination of a human’s ears and brain is a formidable one, say audio experts. Our hearing enables us to determine loudness, pitch, and tone and to approximate the direction and distance of a sound source. The frequency range of a healthy human ear is roughly 20 to 20,000 hertz, or cycles of sound oscillation per second. The most sensitive region is in the 1,000 to 5,000 hertz range. Moreover, we may be able to detect a change of just one hertz from, say, 440 hertz to 441 hertz.
Indeed, a healthy ear is so sensitive that it can detect sounds when the vibration, or to-and-fro movement, of the air at the eardrum is less than the diameter of an atom! According to a university course on hearing, “the human hearing system is close to the theoretical physical limits of sensitivity. . . . There would be little point in being much more sensitive to sound, as all we would hear would be a ‘hiss,’” the result of the random movement of the atoms and molecules that make up the air.
Eardrum vibrations are amplified mechanically by lever action and are transferred to the inner ear by means of the ossicles—tiny bones known as the hammer, the anvil, and the stapes. But what if your ears are suddenly struck by a deafening sound? In that event, they have a built-in protective mechanism in the form of muscle action that adjusts the ossicles to reduce the force of the sound. However, the ears are not equipped to deal with prolonged loud noise. Such exposure can permanently damage the hearing. So take good care of this “wonderfully made” gift from your Creator.—Psalm 139:14.
Your auditory system also helps you to detect a sound source. The secret lies in a number of factors, including the shell-like shape of the outer ear, its grooves, the separation of the two ears, and some computational brilliance on the part of your brain. Thus, if the intensity of a sound fades just slightly from ear to ear or if the sound reaches one ear just 30 millionths of a second before it reaches the other, your brain will promptly point your eyes toward the sound source.
Imagine if you had to make all those computations consciously! To be sure, you would have to know how to use very advanced mathematics—and with lightning speed! If an engineer were to design a “hearing” system that came even remotely close to the one your Creator gave you, he would receive many accolades. Yet, how often do you hear people give due credit to God for his awesome works?—Romans 1:20.
The Human Eye
Some researchers estimate that people who can see well gain approximately 80 percent of their information about the world through their eyes. In combination with our brain, our eyes enable us to see in full color, to track moving objects and images smoothly, to recognize patterns and shapes, and to see in three dimensions. Furthermore, we can see in varying degrees of light.
The latter involves a number of complementary mechanisms. For example, the pupil can expand from 0.06 inch to 0.3 inch (1.5 mm to 8 mm) in diameter, resulting in a possible 30-fold increase in the amount of light entering the eye. The light then passes through the lens, which focuses it onto the retina, concentrating the light energy by a factor of 100,000 times. So never look directly at the sun with the naked eye!
The retina, in turn, houses two types of photoreceptors—cones (approximately 6 million), which give us color vision and high resolution, and rods (120-140 million), which are more than a thousand times as sensitive as the cones and help us to see in dim light. Indeed, under optimal conditions, a rod can detect a single photon, or elementary particle of light!
Another adaptive mechanism involves retinal neurons linked to the cones and rods. These neurons adapt “in seconds and can improve night vision by a factor of 10 or more,” says the American Optometric Association. “Neural adaptation is rather like having low-speed and high-speed film simultaneously available in your camera.”
Engineers often design cameras, scanners, and computers, along with compatible software. But the degree of integration and the level of sophistication attained are vastly inferior to those of our sensory system. Ask yourself, ‘Is it reasonable to attribute our vastly superior living sensory system to blind chance, as evolutionists do?’ An ancient servant of God named Job knew little about the human body compared with what we know today. Even so, he felt impelled to say to God: “Your own hands have shaped me.”—Job 10:8.
YOUR AMAZING BRAIN
How does your brain feel, hear, see, and smell? Scientists are baffled. “There is no hint in your brain as to how you see the words you are now reading,” said scientist Gerald L. Schroeder.
He also wrote: “Revelation of the previously unimagined intricate workings of the brain has challenged the simplistic theory of life’s random evolution.” He continued: “Had Darwin known of the wisdom hidden within life, I have confidence that he would have proposed a very different theory.”
The Human Brain
With astonishing efficiency, the brain decodes the streams of signals pouring in through the nerves from the sense organs. Moreover, it links these signals with details stored in its memory. Thus, a certain smell may immediately trigger the brain to retrieve a long-forgotten experience or event. And if you see just a small part of something familiar—the tip of your cat’s tail, for example—your brain will fill in the missing details so that you know your cat is nearby.
Of course, your brain was not preprogrammed with images of cats, just as it was not preprogrammed with the smell of a rose or the sound of running water or the feel of fur. Your brain learned these associations. The experiences of people who were born blind but have been given the ability to see, perhaps through surgery, make this evident. Their brain had to learn to interpret the flood of visual signals now flowing to it. How do such people fare?
They soon report the ability to detect color, motion, and simple forms. But after that, progress varies. Children, especially the very young, continue to learn quite well. But that is not the case with adults. Even their ability to recognize faces remains highly impaired. And, tragically, a common feature with “cured” adults “is initial euphoria followed by disappointment and disorientation with the restored vision, often leading to severe depression,” says the Koch Laboratory at the California Institute of Technology.
These facts help us to appreciate more fully the degree of healing that Jesus Christ performed during his ministry on earth. The blind and the deaf not only had their eyes and ears opened but also began to recognize the sights and sounds around them. Likewise, the mute spoke normally, which would have been especially amazing in the case of those who were born with this disability. (Matthew 15:30; Mark 8:22-25; Luke 7:21, 22) And we can be confident that none of the blind who were healed spiraled into depression. In fact, one healed man courageously defended Jesus, saying to Jesus’ religious enemies: “From of old it has never been heard that anyone opened the eyes of one born blind. If this man were not from God, he could do nothing at all.”—John 9:1-38.
In the following article, we will examine some of our inner qualities, including courage and love. Have you wondered why humans alone have the potential to display such qualities? To be sure, the existence of such uniquely human traits has presented a major obstacle to people who wish to prove that we are merely highly evolved animals.