Recently some American scientists have given a useful piece of advice to people in industrialized nations．They say people should eat more of the same kind of food eaten by humans living more than 10,000 years ago． {#blank#}1{#/blank#}

     The scientists say that the human life has changed greatly．Our bodies have not been able to deal with these changes in life style and this had led to new kinds of sicknesses． {#blank#}2{#/blank#} So they are called "diseases of civilization"．Many cancersand diseases of the blood system are examples of such diseases.

      Scientists noted that people in both the Old Stone Age and the New Stone Age enjoyed very little alcohol or tobacco, probably none． {#blank#}3{#/blank#}  However, a change in food is one of the maindifferences between life in ancient times and that of today.

      Stone Age people hunted wild animals for their meat, which hadmuch less fat than domestic ones．They ate a lotof fresh wild vegetables and fruits．They did nothave milk or any other dairy products, and they made very little use of grains． {#blank#}4{#/blank#}  We eat six times more salt than our ancestors．We eat moresugar．We eat twice as much fat but only one third as much protein andmuch less vitamin C.

{#blank#}5{#/blank#} But scientists say that we would be much healthier if weeat much the same way the ancient people did, cutting the amount of fatty,salty and sweet food.

A．Stone Agepeople lived a simple life.

B．But today, weenjoy eating a lot of these.

C．In that case,they would live much healthier.

D．Ancient people also got lots of physical exercise.

E．These new sicknesses were not known in ancient times.

F．People today probably don't want to live like our ancestors.

G．Modern people used to suffer from "diseases of civilization".

    Deserts are found where there is little rainfall or where rain for a whole year falls in only a few weeks' time. Ten inches of rain may be enough for many plants to survive if the rain is spread throughout the year. If it falls within one or two months and the rest of the year is dry, those plants may die and a desert may form.

    Sand begins as tiny pieces of rock that get smaller and smaller as wind and weather wear them down. Sand dunes (沙丘) are formed as winds move the sand across the desert. Bit by bit, the dunes grow over the years, always moving with the winds and changing the shape. Most of them are only a few feet tall, but they can grow to be several hundred feet high.

There is, however, much more to a desert than sand. In the deserts of the southwestern United States, cliffs (悬崖) and deep valleys were formed from thick mud that once lay under a sea more than millions of years ago. Over the centuries, the water dried up. Wind, sand, rain, heat and cold all wore away at the remaining rocks. The faces of the desert mountains are always changing –-very, very slowly —as these forces of nature continue to work on the rock.

    Most deserts have a surprising variety of life. There are plants, animals and insects that have adapted to life in the desert. During the heat of the day a visitor may see very few signs of living things, but as the air begins to cool in the evening, the desert comes to life. As the sun begins to rise again in the sky, the desert once again becomes quiet and lonely.

    Even though it's not the most popular time of year to get married, I allow my thoughts to wander and consider the most unusual marriage habits across the world.

    In some parts of India it is believed that ghosts can stay with certain people of the living world. In general, girls who are born with a baby tooth and girls who are very ugly or have some facial damage are believed to be owned by ghosts. The only way to free from the ghosts is for the girl to marry an animal, typically a goat or a dog. She is free to marry a man later on, when the ghosts are proven to be freed from her. I wonder who makes this decision and how they come to their conclusion.

    In Korea, it is a custom for grooms to request that their successfully married friends carve them wooden ducks as a symbol of great marriage. Hand-carving a wooden duck can't be easy. This leads me to wonder why it's a duck and not another animal.

    Imagine being as young as 5 and already your parents are sending you to a fat farm where you are forced to eat too much food until you vomit (呕吐). Then, the old woman watching you eat forces you to eat that vomit. This is not a TV show. This is really happening in some parts of Africa. Men there want women fat; the fatter the better. It doesn't matter if it ruins their health or make them live shorter lives. All that matters is that the woman is as large as possible in order to sell her for a high price when she reaches the age for marrying.

    Everyone knows that if a dog's ears are up and its tail is wagging vigorously, it is definitely pleased to see you, but now scientists using a robot have found that the way dogs use their tails is more complicated than we thought, and that dogs which wag them to the left may he more friendly. The animal psychologists discovered that when real dogs approached a life-sized robot dog, they were less cautious about it when it was wagging its tail to the left, while if it was wagging its tail to the right, far fewer dogs approached it in a confident manner.

    In the first experiments, 56 percent of the animals approached the model without hesitation when the tail was wagged to the left, while only 21 percent did so in the other situation. When the researchers excluded (排除) owners from being present, the result were: 31 percent of the dogs approached continuously when the tail was wagging to the left, while only 18 percent did so when it was on the right.

    Animal psychologist Roger Mugford said it added to the growing evidence that does were even more complicated communicators than the animals more closely related to man such as monkeys. He said, "We know that dogs, in a sense, have languages, but it is more complicated because it is not just them wagging their tails, but also giving out chemical displays."

    He adds, "The research confirms earlier studies suggesting that dogs, like humans, had a left-side preference. If you are going to present a signal to a dog, it is sensible to put it on your left-hand side because that is where dogs, unlike most other animals, tend to look. It is another example of the similarity between dogs and humans. They are a lot more human than we give them credit for."

    Self-driving cars have been backed by the hope that they will save lives by getting involved in fewer crashes with fewer injuries and deaths than human-driven cars. But so far, most comparisons between human drivers and automated vehicles have been unfair.

    Crash statistics for human-driven cars are gathered from all sorts of driving situations, and on all types of roads. However, most of the data on self-driving cars' safety have been recorded often in good weather and on highways, where the most important tasks are staying in the car's own lane and not getting too close to the vehicle ahead. Automated cars are good at those tasks, but so are humans.

    It is true that self-driving cars don't get tired, angry, frustrated or drunk. But neither can they yet react to uncertain situations with the same skill or anticipation of an attentive human driver. Nor do they possess the foresight to avoid potential perils. They largely drive from moment to moment, rather than think ahead to possible events literally down the road.

    To a self-driving car, a bus full of people might appear quite similar to an uninhabited corn field. Indeed, deciding what action to take in an emergency is difficult for humans, but drivers have sacrificed themselves for the greater good of others. An automated system's limited understanding of the world means it will almost never evaluate (评估) a situation the same way a human would. And machines can't be programmed in advance to handle every imaginable set of events.

    Some people may argue that the promise of simply reducing the number of injuries and deaths is enough to support driverless cars. But experience from aviation (航空) shows that as new automated systems are introduced, there is often an increase in the rate of disasters.

    Therefore comparisons between humans and automated vehicles have to be performed carefully. To fairly evaluate driverless cars on how well they fulfill their promise of improved safety, it's important to ensure the data being presented actually provide a true comparison. After all, choosing to replace humans with automation has more effects than simply a one-for-one exchange.

    By analyzing the fossilized teeth of some of our most ancient ancestors, a team of scientists led by the universities of Bristol (UK) and Lyon (France) have discovered that the first humans significantly breastfed their infants (婴儿) for longer periods than their contemporary relatives.

    The results, published in the journal Science Advances, provide a first insight into the practice of weaning (断奶)that remain otherwise unseen in the fossil record.

    The team sampled minute amounts from nearly 40 fossilized teeth of our South African fossil relatives, early Homo, Paranthropus robustus and Australopithecus africanus. They measured the proportions of their stable calcium isotopes (同位素）in the tooth enamel(牙釉质), which are a function of the mother milk intake by infants. They show that early Homo offspring(后代) was breastfed in significant proportions until the age of around three to four years, which likely played a role in the apparition of traits that are specific to human lineage(血统), such as the brain development.

    In contrast, infants of Paranthropus robustus, that became extinct around one million years ago and were a more robust species in terms of dental anatomy, as well as infants of Australopithecus africanus, stopped drinking sizeable proportions of mother milk in the course of the first months of life.

    These differences in nursing behaviors likely come with major changes in the social structures of groups as well as the time between the birth of one child and the birth of the next.

    One of the study's lead authors, Dr Theo Tacail said: "The practice of weaning -- the duration of breastfeeding, age at non-milk food introduction and the age at cessation of suckling -- differs among the modern members of the hominid family which includes humans and modern great apes: orangutan, gorillas, chimpanzees and bonobos.

    The development of such behavioral differences likely played major roles in the evolution of the members of human lineage, being associated for instance with size and structure of social groups, brain development.

    However, getting insights into these behavioral changes from fossils that are millions of years old is a challenge and, so far, little evidence allow discussing nursing practices in these fossil species.

    The findings stress the need for further exploration of calcium stables isotopes compositions in the fossil record in order to understand the co-evolution of weaning practices with other traits such as brain size or social behaviors."

http://www.dentaldailynews.com/first-human-ancestors-breastfed-for-longer-than-contemporary-relatives/

https://www.sciencedaily.com/releases/2019/08/190829115427.htm