Intriguing results of the last few years suggest a protective effect of life-long bilingualism against Alzheimer’s symptoms. Among 400 patients studied at clinics in Toronto, Canada, mostly in their 70s, and with a probable diagnosis of Alzheimer’s disease (or other dementias in a few cases), bilingual patients showed their first symptoms at an age 4 or 5 years older than did monolingual patients. Life expectancy in Canada is 79, hence a delay of 4–5 years for people in their 70s translates into a 47% decrease of probability that they will develop Alzheimer’s symptoms at all before they die. The bilingual and monolingual patients were matched in occupational status, but the bilingual patients had received on the average lower (not higher) levels of education. Because education is associated with lower incidence of Alzheimer’s symptoms, this means that differences in education could not explain the lower incidence of symptoms in the bilingual patients: their lower incidence was despite their having received less education. A further intriguing finding was that, for a given level of cognitive impairment, bilingual patients had more brain atrophy revealed by brain-imaging methods than did monolingual patients. Expressing this differently, bilingual patients suffer less cognitive impairment than do monolingual patients with the same degree of brain atrophy: bilingualism offers partial protection against the consequences of brain atrophy.
The protection afforded by bilingualism does not raise the same uncertainties of interpretation about cause versus effect raised by the apparent protection offered by education and stimulating social activities. The latter might be results rather than causes of early stages of Alzheimer’s lesions; and genetic factors predisposing one to seek education and social activities might also protect one against Alzheimer’s disease. But whether one becomes bilingual is determined in early childhood, decades before the earliest Alzheimer’s brain lesions develop, and regardless of one’s genes. Most bilingual people become bilingual not through any decision or genes of their own, but through the accident of growing up in a bilingual society, or of their parents emigrating from their native land to a land with a different language. Hence the reduced Alzheimer’s symptoms of bilinguals suggest that bilingualism itself protects against Alzheimer’s symptoms.
How might this be? A short answer is the aphorism “Use it or lose it.” Exercising most body systems improves their function; failing to exercise them lets their function deteriorate. This is the reason why athletes and artists practise. It’s also the reason why Alzheimer’s patients are encouraged to play bridge or online games, or to solve Sudoku puzzles. But bilingualism is the most constant practice possible for the brain. Whereas even a bridge or Sudoku fanatic can play bridge or solve Sudoku puzzles for only a fraction of a day, bilingual people impose extra exercise on their brain every second of their waking hours. Consciously or unconsciously, their brain is constantly having to decide, “Shall I speak, think, or interpret sounds spoken to me according to the arbitrary rules of language A, or of language B?”
Readers will share my personal interest in some unanswered but obvious further questions. If one extra language offers some protection, do two extra languages offer more protection? If so, does the protection increase in direct proportion to the number of languages, or else more steeply or less steeply? For instance, if bilingual people get four years of protection from their one extra language, does a New Guinean, an Aboriginal Australian, a Vaupés River Indian, or a Scandinavian shopkeeper speaking five languages (four beyond her first language) still get just 4 years of protection, or does she get 4 × 4 = 16 years of protection, or (if juggling four extra languages is much more than four times more taxing than juggling just one extra language) does she even get 50 years of protection? If you had the misfortune that your parents didn’t raise you as a crib bilingual, and that you didn’t learn a second language until you began high school at age 14, can you ever catch up to crib bilinguals in the benefits obtained? Both of these questions will be of theoretical interest to linguists, and of practical interest to parents wondering how best to raise their children. All of this suggests that bilingualism or multilingualism may bring big practical advantages to bilingual individuals, beyond the less practical advantages of a culturally enriched life, and regardless of whether language diversity is good or bad for the world as a whole.
Vanishing languages
The world’s 7,000 languages are enormously diverse in a wide range of respects. For instance, one day while I was surveying birds in jungle around Rotokas village in the mountains of the Pacific island of Bougainville, the villager guiding me and naming local birds for me in the Rotokas language suddenly exclaimed “Kópipi!” as he pointed out the most beautiful bird song that I had ever heard. It consisted of silver-clear whistled tones and trills, grouped in slowly rising phrases of two or three notes, each phrase different from the previous one, and producing an effect like one of Franz Schubert’s deceptively simple songs. The singer proved to be a species of long-legged short-winged warbler previously unknown to Western science.
As I talked with my guide, I gradually realized that the music of Bougainville’s mountains included not only the kópipi’s song but also the sound of the Rotokas language. My guide named one bird for me after another: kópipi, kurupi, vokupi, kopikau, kororo, keravo, kurue, vikuroi…. The only consonant sounds from those names are k, p, r, and v. Later, I learned that the Rotokas language has only 6 consonant sounds, the fewest of any known language in the world. English, by comparison, has 24, while the now-extinct Ubykh language of Turkey had about 80. Somehow, the people of Rotokas, living in a tropical rainforest on the highest mountain of the Southwest Pacific Ocean east of New Guinea, have managed to build a rich vocabulary and communicate clearly while relying on fewer basic sounds than any other people in the world.
But the music of their language is now disappearing from Bougainville’s mountains, and from the world. The Rotokas language is just 1 of 18 languages spoken on an island roughly three-quarters the size of the American state of Connecticut. At last count it was spoken by only 4,320 people, and that number is declining. With its vanishing, a 30,000-year experiment in human communication and cultural development will come to an end. That vanishing exemplifies the impending tragedy of the loss not just of the Rotokas language, but of most of the world’s other languages. Only now are linguists starting seriously to estimate the world rate of language loss, and to debate what to do about it. If the present rate of language disappearance continues, then by the year 2100 most of the world’s current languages will either already be extinct, or else will be moribund languages spoken only by old people and no longer being transmitted from parents to children.
Of course, language extinction isn’t a new phenomenon that began only 70 years ago. We know from ancient written records, and we infer from distributions of languages and peoples, that languages have been going extinct for thousands of years. From Roman authors and from scraps of writing on ancient monuments and coins in the territory of the former Roman Empire, we know that Latin replaced Celtic languages formerly spoken in France and Spain, and replaced Etruscan, Umbrian, Oscan, Faliscan, and other languages within Italy itself. Preserved ancient texts in Sumerian, Hurrian, and Hittite attest to now-vanished languages spoken several thousand years ago in the Fertile Crescent. The spread of the Indo-European language family into western Europe, beginning within the last 9,000 years, eliminated all the original languages of Europe except for the Basque language of the Pyrenees. We infer that African Pygmies, Philippine and Indonesian hunter-gatherers, and ancient Japanese people spoke now-vanished languages replaced by Bantu languages, Austronesian languages, and the modern Japanese language respectively. Far more languages must have vanished without a trace.