“The prefrontal cortex . . . is most involved with elaboration of thought, intelligence, motivation, and personality. It associates experiences necessary for the production of abstract ideas, judgment, persistence, planning, concern for others, and conscience. . . . It is the elaboration of this region that sets human beings apart from other animals.” (Marieb’s Human Anatomy and Physiology) We certainly see evidence of this distinction in what humans have accomplished in fields such as mathematics, philosophy, and justice, which primarily involve the prefrontal cortex.

Why do humans have a large, flexible prefrontal cortex, which contributes to higher mental functions, whereas in animals this area is rudimentary or nonexistent? The contrast is so great that biologists who claim that we evolved speak of the “mysterious explosion in brain size.” Professor of Biology Richard F. Thompson, noting the extraordinary expansion of our cerebral cortex, admits: “As yet we have no very clear understanding of why this happened.” Could the reason lie in man’s having been created with this peerless brain capacity?

Unequaled Communication Skills

Other parts of the brain also contribute to our uniqueness. Behind our prefrontal cortex is a strip stretching across the head—the motor cortex. It contains billions of neurons that connect with our muscles. It too has features that contribute to our being far different from apes or other animals. The primary motor cortex gives us “(1) an exceptional capability to use the hand, the fingers, and the thumb to perform highly dexterous manual tasks, and (2) use of the mouth, lips, tongue, and facial muscles to talk.”—Guyton’s Textbook of Medical Physiology.

Consider briefly how the motor cortex affects your ability to speak. Over half of it is devoted to the organs of communication. This helps to explain the unparalleled communication skills of humans. Though our hands play a role in communication (in writing, normal gestures, or sign language), the mouth usually plays the major part. Human speech—from a baby’s first word to the voice of an elderly person—is unquestionably a marvel. Some 100 muscles in the tongue, lips, jaw, throat, and chest cooperate to produce countless sounds. Note this contrast: One brain cell can direct 2,000 fibers of an athlete’s calf muscle, but brain cells for the voice box may concentrate on only 2 or 3 muscle fibers. Does that not suggest that our brain is specially equipped for communication?

Each short phrase that you utter requires a specific pattern of muscular movements. The meaning of a single expression can change depending upon the degree of movement and split-second timing of scores of different muscles. “At a comfortable rate,” explains speech expert Dr. William H. Perkins, “we utter about 14 sounds per second. That’s twice as fast as we can control our tongue, lips, jaw or any other parts of our speech mechanism when we move them separately. But put them all together for speech and they work the way fingers of expert typists and concert pianists do. Their movements overlap in a symphony of exquisite timing.”

The actual information needed to ask the simple question, “How are you today?” is stored in a part of your brain’s frontal lobe called Broca’s area, which some consider to be your speech center. Nobel laureate neuroscientist Sir John Eccles wrote: “No area corresponding to the . . . speech area of Broca has been recognized in apes.” Even if some similar areas are found in animals, the fact is that scientists cannot get apes to produce more than a few crude speech sounds. You, though, can produce complicated language. To do so, you put words together according to the grammar of your language. Broca’s area helps you do that, both in speaking and in writing.

Of course, you cannot exercise the miracle of speech unless you know at least one language and understand what its words mean. This involves another special part of your brain, known as Wernicke’s area. Here, billions of neurons discern the meaning of spoken or written words. Wernicke’s area helps you to make sense of statements and to comprehend what you hear or read; thus you can learn information and can respond sensibly.

There is even more to your fluent speech. To illustrate: A verbal “Hello” can convey a host of meanings. Your tone of voice reflects whether you are happy, excited, bored, rushed, annoyed, sad, or frightened, and it may even reveal degrees of those emotional states. Another area of your brain supplies information for the emotional part of speech. So, various parts of your brain come into play when you communicate.

Chimpanzees have been taught some limited sign language, but their use of it is essentially limited to simple requests for food or other basics. Having worked to teach chimps simple nonverbal communication, Dr. David Premack concluded: “Human language is an embarrassment for evolutionary theory because it is vastly more powerful than one can account for.”

We might ponder: ‘Why do humans have this marvelous skill to communicate thoughts and feelings, to inquire and to respond?’ The Encyclopedia of Language and Linguistics states that “[human] speech is special” and admits that “the search for precursors in animal communication does not help much in bridging the enormous gap that separates language and speech from nonhuman behaviors.” Professor Ludwig Koehler summarized the difference: “Human speech is a secret; it is a divine gift, a miracle.”

What a difference there is between an ape’s use of signs and the complex language ability of children! Sir John Eccles referred to what most of us have also observed, an ability “exhibited even by 3-year-old children with their torrent of questions in their desire to understand their world.” He added: “By contrast, apes do not ask questions.” Yes, only humans form questions, including questions about the meaning of life.

Memory and More!

When you glance in a mirror, you may think of how you looked when you were younger, even comparing that with what your appearance could be in the years to come or how you would look after applying cosmetics. These thoughts can arise almost unconsciously, yet something very special is occurring, something that no animal can experience.

Unlike animals, who mainly live and act on present needs, humans can contemplate the past and plan for the future. A key to your doing that is the brain’s almost limitless memory capacity. True, animals have a degree of memory, and thus they can find their way back home or recall where food may be. Human memory is far greater. One scientist estimated that our brain can hold information that “would fill some twenty million volumes, as many as in the world’s largest libraries.” Some neuroscientists estimate that during an average life span, a person uses only 1/100 of 1 percent (.0001) of his potential brain capacity. You might well ask, ‘Why do we have a brain with so much capacity that we hardly test a fraction of it in a normal lifetime?’

Nor is our brain just some vast storage place for information, like a supercomputer. Biology professors Robert Ornstein and Richard F. Thompson wrote: “The ability of the human mind to learn—to store and recall information—is the most remarkable phenomenon in the biological universe. Everything that makes us human—language, thought, knowledge, culture—is the result of this extraordinary capability.”

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“The human brain is composed almost exclusively of the [cerebral] cortex. The brain of a chimpanzee, for example, also has a cortex, but in far smaller proportions. The cortex allows us to think, to remember, to imagine. Essentially, we are human beings by virtue of our cortex.”—Edoardo Boncinelli, director of research in molecular biology, Milan, Italy.

● The Cerebral Cortex is the surface region of the brain that is most strongly linked to intelligence. A human’s cerebral cortex, if flattened, would cover four pages of typing paper; a chimpanzee’s would cover only one page; and a rat’s would cover a postage stamp.—Scientific American.