题型：阅读理解 题类：常考题 难易度：普通
江苏省镇江市2020届高三上学期英语期中考试试卷
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
You walk into the classroom, look at that white piece of paper in front of you and are told you've got an hour and a half to do it. That can make anyone nervous, but here is the guide to stay calm.
Get a good night's sleep the night before the test, and eat a healthy breakfast next day. {#blank#}1{#/blank#} If you're too tired, you won't remember what you learnt the night before.
Get to class a little earlier. If you get there early, you'll make sure to get your favorite seat. {#blank#}2{#/blank#}
Breathe. Before the test, breathe in through your nose deeply and slowly. {#blank#}3{#/blank#} Repeat this several times. If you experience a sudden panic during the test, perform the exercise again.
Skip questions if necessary. {#blank#}4{#/blank#} If you come across a difficult question, skip the question and move on. You can come back to it at the end of the test if you have time, and later questions may help you get the answer(s) to the one(s) you skipped.
{#blank#}5{#/blank#} Don't panic if you notice other students writing very quickly or handing in their tests early. Tell yourself it's just a test. Really, it is. No matter what happens, everything will be OK.
A. Avoid staying up the night before the exam. B. Act like you are the only person in the room. C. Don't spend too much time on any one question. D. If you believe you can do it, you will find you can! E. A little exercise will help you remain calm during any stressful situation. F. Then, hold your breath for 3-4 seconds and blow out slowly through your mouth. G. You'll not also feel more relaxed if you don't get there in time or worse yet, late. |
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