The evolution and physiology of language PDF

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Evolution and physiology of language

Nonhuman Precursors of language While nonhuman animals communicate through visual, auditory, tactile, or chemical (pheromonal) displays, those signals don’t have much flexibility compared to human language, with its productivity and ability to improvise new combinations of signals to represent new ideas.

Common Chimpanzees attempts to teach chimpanzees to talk failed because unlike humans who vocalize while breathing out, chimpanzees vocalize while breathing in. Chimpanzees in the wild do communicate with gestures, and investigators achieved better results by teaching them American Sign Language or other visual systems However, the chimps’ use of symbols had features that raised doubts about calling it language, such as the lack of new, original combinations & descriptions as opposed to requests.

Bonobos

A female Bonobo named Matata made little progress in learning symbols, while her infant son Kanzi learned just by watching her. Kanzi and his younger sister developed language comprehension comparable to that of a typical 2 to 2 1⁄2 year old child. They understand more than they can produce They follow unfamiliar, unlikely directions They could describe objects & past events They requested items they could not see & made original, creative requests. Learning by observation & imitation promotes better language understanding than the formal training methods of previous studies.

Parrots Parrots are famous for imitating sounds, and a parrot named Alex was successfully taught to communicate simple English sentences.

Language seemed to have no evolutionary benefit for animals.

How did Humans evolve language? These animal studies indicate that human language evolved from precursors present in other species.

Precursors: The phonological loop, the ability to hear something and remember it, could have enabled vocal communication but wasn't sufficient for the development language. Compared to other primates, the human brain has stronger connections between the auditory cortex and the prefrontal cortex, enabling much greater auditory memory A combination of sound and mouth gestures that primates and even monkeys use to communicate, could have been a precursor to spoken language.

Children begin gesturing in the first year of life, and their ability to communicate by gestures predicts how soon they will develop spoken language. Most adults also accompany most of their speech with gestures.

Theories: Humans evolved big brains for some other reason and language developed as an accidental by-product of intelligence. Criticisms: elephants, whales, and dolphins have larger brains than humans, but no language. Some people show severe language deficits despite normal intelligence in other regards. This shows that language requires more than just a large brain and overall intelligence Some people are able to use relatively spared language but have low overall intelligence, such as people with Williams syndrome (caused by the deletion of chromosome 7 & decreased gray matter in visual processing centre), who are poor at tasks related to numbers, attention, planning, visuomotor skills, spatial perception and have trouble inhibiting inappropriate responses but are still able to speak grammatically and fluently. Language evolving as a specialised brain mechanism and having a genetic basis is proposed with the concept of the language acquisition device, a built-in mechanism for acquiring language. Most children develop language so quickly and easily that it seems they must have been biologically prepared for this learning. Deaf children quickly learn sign language, and if no one teaches them a sign language, they invent one and teach it to one another FOXP2 is a gene that regulates a protein that promotes synapse formation in the cerebral cortex and also produces changes in structures of the jaw and throat that are important for speech Social interactions among people, including those between parents and children (such as the period of dependency in childhood), favoured the evolution of language. overall intelligence may be a by-product of language development

A Sensitive Period for language learning While adults are better than children at memorizing the vocabulary of a second language, children have a great advantage when it comes to learning pronunciation and grammar.

people who start learning a second language beyond age 12 or so almost never reach the level of a true native speaker.

People who grow up speaking 2 languages from the start, show substantial bilateral activity during speech for both languages, while those who learn a second language after age 6 only activate their left hemispheres for both languages.

In addition to the benefit of being able to communicate with more people, bilinguals also learn to control their attention better than average.

A child who learns spoken or sign language early can learn the latter language later, but a child who learns no language while young is permanently impaired at learning any kind of language.

Brain damage and language Broca’s Aphasia (Nonfluent Aphasia) Broca's aphasia is when brain damage impairs language production, regardless of the location of the damage. Broca’s area contributes to language production, however, damage limited to Broca’s area produces only minor or brief language impairment. This is because: speaking also activates much of the left hemisphere, not just Broca's area.

The role of each brain area can change over time, especially in response to damage of another area Most cases of Broca's aphasia results from combined damage to areas of the basal ganglia that lie interior to Broca’s area of the cortex, as well as other parts of the cortex and thalamus People with Broca’s aphasia are slow and awkward with all forms of language communication, including speaking, writing, gesturing & sign language They generally omit pronouns, prepositions, conjunctions, auxiliary (helping) verbs, quantifiers, and tense and number endings This seems to be due to the word's meaning itself instead of pronunciation They seem to be leaving out the weaker elements of language, much like how people in pain would talk. People with Broca’s aphasia understand most speech, except when the meaning depends on prepositions, word endings, or complex grammar (the same items that they omit when speaking). People with Broca’s aphasia have not totally lost their knowledge of grammar, and generally seem to understand something is wrong with ungrammatical sentences.

Wernicke’s Aphasia (Fluent Aphasia) Wernicke’s aphasia is characterized by poor language comprehension and impaired ability to remember the names of objects. Caused by damage to Wernicke's area, although, the damage generally extends beyond the cortex into the thalamus and basal ganglia. located near the auditory cortex Those with Wernicke’s aphasia speak fluently, however, they have anomia, or difficulty recalling the names of objects. They also have trouble understanding speech, writing, and sign language.

Dyslexia Dyslexia is a specific impairment of reading in someone with adequate vision, motivation, cognitive skills, and educational opportunity. It is more common in boys than girls, and occurs in all languages, pertaining to a difficulty converting symbols into sounds Types of dyslexia: People with dysphonetic dyslexia have trouble sounding out words, so they try to memorize each word as a whole, and when they don’t recognize a word, they guess based on context. People with dyseidetic dyslexia sound out words well enough, but they fail to recognize a word as a whole. They read slowly and have trouble with irregularly spelt words. May be caused by abnormalities in the left hemisphere for people with dyslexia (with some appearing very early in life). Certain parts of their temporal cortex are larger in the right hemisphere than in the left, unlike most other people. Most (but not all) have auditory problems, a smaller number have impaired control of eye movements, and some have both Some have poor auditory memory and weaker than normal connections between the auditory cortex and Broca’s area Many have trouble detecting the temporal order of sounds, such as noticing the difference between beep-click-buzz and beep-buzz-click They also have difficulty making Spoonerisms, trading the first consonants of two words, such as listening to “dear old queen” and saying “queer old dean” They are unusually adept at identifying letters well to the right of their fixation point, and this kind of abnormality in attention (a wide attentional focus), could disrupt attempts to read....