Saturday, November 10, 2007

10 Amazing Facts about Human Speech

1.The speech skill is a wonder. To produce a phrase, about 100 muscles of the chest, neck, jaw, tongue and lips must collaborate. Each muscle is a bundle made of hundreds or thousands of fibers. For the coordination of these muscles much more neurons than necessary are required for contracting the muscles from an athlete's feet. Just one motor neuron can trigger movement in the 2,000 muscular fibers existent on a calf muscle. But the neurons controlling the vocal cords or the larynx can be bound just one to two-three muscle cells.

2.Each spoken word or short phrase is accompanied by its own pattern of muscular movements. All the information necessary for speaking a phrase like "How are you?" is stored in the brain, in the speech area. But it's not about a fixed program. If you have a mouth wound impeding you to pronounce the words like you usually do, the movements are modified, allowing you to utter the words as closely as possible to normal.

3.A simple "Hallo" can transmit a lot of things. The voice's tone shows if the speaker is happy, pleased, bored, hurried, angry, sad, scared, aggressive or dominant and the intensity of these states; irony, affection, support or joke. The sense of a simple expression can be changed according to the rapidity of the movements and the fractions of seconds depending on how much the movement of different muscles lasts.

4.Humans can emit about 14 seconds per second, while isolated parts of the speech apparatus, like tongue, lips, jaws and others cannot execute more than 2 movements per second.

5.Early humans could have had a rudimentary speech system of visual, tactile and auditive calls, resembling animal communication. Speech appeared when we acquired the ability of representing objects through symbols and communicate to another individual our own mental creations. Our special brain enabled us to do this.

The first symbolic language emerged 2.5 million years ago, when Homo habilis started to fabricate the first stone tools. This ability surely played a key role in the development of symbolic communication. Articulating went perfecting till first Homo sapiens, 150,000 years ago, emitting sounds similar to that spoken by modern humans.

The mouth, nose and larynx ended by transforming themselves into a refined apparatus, in which the air was converted into vowels and consonants due to a better position of the tongue and lips. Moreover, the acquisition of a grammar and syntax was the result of an evolutionary process, while the writing ability was the consequence of the phonetic interpretation of the primitive icons.

6.Is speech born or acquired? Famous cases of children lost in the jungle before the age of three (when speech is largely acquired) and found several years later showed they had limited ability to learn the human speech and learning the speech requires early interaction with the others. The brain seems to have a period when it acquires speech and if this period is skipped over, the individual won't gain later the speech skill. The speech can develop only inside a community and at the age when the brain is growing.

7.The complex human speech has been linked to two brain nuclei controlling the language (articulating control, data storing and integration of the grammar rules) located in the left hemisphere of the cortex. What we want to say is initiated in an area of the left cortex called "Wernicke zone". This communicates with "Broca zone", involved with grammatical rules. Impulses go from these areas to the muscles involved in speech. These zones are connected with the visual system (so we can read), auditory system (so we can hear what others say, understand and answer) and also have a memory bank for recalling valuable phrases.

The same left hemisphere controls the movements of the right hand and 99 % of the humans are right-handed. The left hemisphere is also the center of analytical thinking, linked to logical abilities.

8.A sudden boost in the evolution of the speech was given by the emergence of the language some 50,000 years ago.

The modern 6,000 languages are believed to have originated in a sole mother language, as humans are believed to have formed just a small population of about 1,000 individuals 50,000 years ago. By now, three super-families of human languages exist.

9.Many ape individuals, of bonobo, chimps, gorillas or orangutans have been taught human sign languages or to manage graphic or computer symbols. Some can learn up to 1,000 words (up to 40 new words daily), but their temporal consciousness is null. Thus, in the end, it is all about brain capacities...

10.There are three major hypotheses about the way human languages emerged:

I.The ingestion by the first humans of psilocybin, a psychoactive alkaloid encountered in some mushrooms could have turned on newly evolved brain parts, like the Broca's area (linked to articulated speech) from the cortex. Neolithic wall paintings found at Tassili-n-Ajjer (Sahara) represent a shaman with the hands full of mushrooms, a fact that corroborates this theory.

II.The "evolutionist argument" speaks about brain innovations, mechanisms that induced a clear advantage. Speech could have boosted served reproductive exit and individual's survival.

III.A sole mutation could have triggered the speech ability. The human languages have a common structure which could be considered innate and characteristic to the species. In 2001, American researchers discovered on the chromosome 7 a gene whose lack amongst the members of a family produced severe difficulties for building phrases and understanding them, even if those persons were really intelligent. This shows that language is not connected to overall intelligence and also the fact that there is a genetic base for the speech.