Book 1 Reading and Speaking (Л.Н. Шевырдяева - Naturally Speaking & Listening), страница 8

Now genetic evidence from modern and ancient horses,published in today's Science, completes the picture: the taming of horses did not occur in only one place, but inseveral, geographically distant locations.Researchers from Sweden and the U.S.

analyzed parts of the mitochondrial DNA of 191 domestic horsesfrom ten different breeds, including the Icelandic Pony, the Arabian horse and the (American) Standardbred. Theyalso included DNA sequences from 12,000 to 28,000-year-old horse bones found in Alaska and from 1,000 to2,000-year-old horse remains from Northern Europe in the comparison. Mothers alone pass on mitochondria totheir offspring, which is why the data represents only the maternal line.

But the DNA samples from the modernhorses differed so much from each other that they probably originated from several different groups ofdomesticated horses. And the genetic variation within each breed indicates that probably more female horses andonly a few studs were used for breeding--a practice that continues today.Rather than giving away domesticated horses, people in Eurasia probably taught each other techniques forcapturing and keeping wild horses from their own area.

That's why today's breeds still carry the genetic hallmarksof many different wild populations. (From Scientific American Online, January 19, 2001)Exercise 5. Answer the following questions:1. When was a wild horse population seen for the last time?2. What methods were used to determine the time of horse domestication?3. What genetic material was used in each study described in the texts?4. When and where did domestication of horses start?5. How was domestication of horses performed?Exercise 6. Make up a list of the 10 key facts about studies of domestication. Agree on the final list of factswith the whole group.Then summarize everything you now know about domestication of wild animals into one report.20Section 1.

Recommended Report and Presentation Topics1. Seizures: classifications, etiology, treatment.2. Epilepsy.3. Malignant tumours.4. Unique abilities of the human body.5. Unique abilities of the human brain.6. Do fresh water and sea water animals drink?7. What do marine organisms drink?8. Why is water considered the most valuable resource of the future?9.

Water conservation.10. Poisonous mushrooms.11. Symbiotic partnerships inside the human body.12. Do bacteria packed yoghurts really benefit our health?13. Extreme bacterial habitats.14. How did different breeds of domestic dogs originate?15. Why were cats domesticated?21Section 2.Unit 6. BrainI’ll give you my opinion of the human race . . .Their heart’s in the right place, but their head isa thoroughly inefficient organ.W. Somerset MaughamIt is good to rub and polish our brains againstthat of others.Michel de MontaigneExercise 1. What do you know about the human brain?1.

What is the structure of the nervous system?2. What are the functions of the brain?3. What is each region of the brain responsible for? Speak about forebrain, midbrain, hindbrain, cerebellum,medulla oblongata, cerebral cortex, etc.4. What is a neuron?5. What are the functions of neurotransmitters?6. What do you know about nerve cell growth (neurogenesis) and neuroplasticity?7. What is intelligence?8. What is memory?Exercise 2. Read introduction to the text. What do you think the possible methods to improve brainpowerare?Six Ways to Boost BrainpowerThe adult human brain is surprisingly malleable: it can rewire itself and even grow new cells. Here are some habitsthat can fine-tune your mindBy Emily AnthesAmputees sometimes experience phantom limb sensations, feeling pain, itching or other impulses comingfrom limbs that no longer exist. Neuroscientist Vilayanur S.

Ramachandran worked with patients who had so-calledphantom limbs, including Tom, a man who had lost one of his arms. Ramachandran discovered that if he strokedTom’s face, Tom felt like his missing fingers were also being touched. Each part of the body is represented by adifferent region of the somatosensory cortex, and, as it happens, the region for the hand is adjacent to the regionfor the face. The neuroscientist deduced that a remarkable change had taken place in Tom’s somatosensorycortex: because Tom’s cortex was no longer getting input from his missing hand, the region processing sensationfrom his face had slowly taken over the hand’s territory.

So touching Tom’s face produced sensation in hisnonexistent fingers.This kind of rewiring is an example of neuroplasticity, the adult brain’s ability to change and remold itself.Scientists are finding that the adult brain is far more malleable than they once thought.

Our behavior andenvironment can cause substantial rewiring of the brain or a reorganization of its functions and where they arelocated. Some believe that even our patterns of thinking alone are enough to reshape the brain. Researchers nowknow that neurogenesis (the birth of new neurons) is a normal feature of the adult brain.

Studies have shown thatone of the most active regions for neurogenesis is the hippocampus, a structure that is vitally important for learningand long-term memory. Neurogenesis also takes place in the olfactory bulb, which is involved in processing smells.But not all the neurons that are born survive; in fact, most of them die. To survive, the new cells need nutrients andconnections with other neurons that are already thriving.

Scientists are currently identifying the factors that affectthe rate of neurogenesis and the survival of new cells. Mental and physical exercise, for instance, both boostneuron survival.Exercise 3. Now divide into pairs or small groups and read about each method. Then tell other studentswhat you have read about. Try not to miss any detail.METHOD 1: EXERCISEMice that run on wheels increase the number of neurons in their hippocampus and perform better on tests oflearning and memory. Studies of humans have revealed that exercise can improve the brain’s executive functions(planning, organizing, multitasking, and more). Exercise is also well known for its mood-boosting effects, andpeople who exercise are less likely to get dementia as they age.

Among those who are already aged, athletic22senior citizens have better executive function than do those who are sedentary; even seniors who have spent theirentire lives on the couch can improve these abilities just by starting to move more in their golden years. You don’tneed to be Chuck Norris (thankfully) to get the brain benefits of exercise. Studies of senior citizens have shown thatas little as 20 minutes of walking a day can do the trick.A variety of mechanisms might be responsible for this brain boost. Exercise increases blood flow to the brain,which also increases the delivery of oxygen, fuel and nutrients to those hard-working neurons. Research hasshown that exercise can increase levels of a substance called brain-derived neurotrophic factor (BDNF), whichencourages growth, communication and survival of neurons.

Exercise also improves sleep quality, a pile of studiessuggests. And immune function. Is there anything it can’t do?METHOD 2: DIETThe brain needs fuel just as the body does. So what will really boost your brainpower, and what will makeyou lose your mind? Saturated fat, that familiar culprit, is no better for the brain than it is for the body. Rats fed dietshigh in saturated fat underperformed on tests of learning and memory, and humans who live on such diets seem tobe at increased risk for dementia.Not all fat is bad news, however. The brain is mostly fat—all those cell membranes and myelin coveringsrequire fatty acids—so it is important to eat certain fats, particularly omega-3 fats, which are found in fish, nuts andseeds.

Alzheimer’s disease, depression, schizophrenia and other disorders may be associated with low levels ofomega-3 fatty acids. It is especially important that babies get enough fat. Babies who don’t get enough of the stuffhave trouble creating the fatty myelin insulation that helps neurons transmit signals. Luckily for babies, breast milkis 50 percent fat.Fruits and vegetables also appear to be brain superfoods. Produce is high in substances called antioxidants,which counteract atoms that can damage brain cells. Researchers have found that high-antioxidant diets keeplearning and memory sharp in aging rats and even reduce the brain damage caused by strokes.