首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Got milk? If you do, take a moment to ponder the true oddness of being able to drink milk after you’re a baby. No other speci
Got milk? If you do, take a moment to ponder the true oddness of being able to drink milk after you’re a baby. No other speci
admin
2011-12-20
92
问题
Got milk? If you do, take a moment to ponder the true oddness of being able to drink milk after you’re a baby.
No other species but humans can. And most humans can’t either.
The long lists of food allergies some people claim to have can make it seem as if they’re just finicky eaters trying to rationalize likes and dislikes. Not so. Eggs, peanuts, tree nuts, fish, shellfish soy and gluten all can wreak havoc on the immune system of allergic individuals, even causing a deadly reaction called anaphylaxis.
But those allergic reactions are relatively rare, affecting an estimated 4% of adults.
Milk’s different.
There are people who have true milk allergies that can cause deadly reactions. But most people who have bad reactions to milk aren’t actually allergic to it, in that it’s not their immune system that’s responding to the milk. Instead, people who are lactose intolerant can’t digest the main sugar-lactose-found in milk. In normal humans, the enzyme that does so-lactase-stops being produced when the person is between two and five years old. The undigested sugars end up in the colon, where they begin to ferment, producing gas that can cause cramping, bloating, nausea, flatulence and diarrhea.
If you’re American or European it’s hard to realize this, but being able to digest milk as an adult is one weird genetic adaptation.
It’s not normal. Somewhat less than 40% of people in the world retain the ability to digest lactose after childhood. The numbers are often given as close to 0% of Native Americans, 5% of Asians, 25% of African and Caribbean peoples, 50% of Mediterranean peoples and 90% of northern Europeans. Sweden has one of the world’s highest percentages of lactase tolerant people.
Being able to digest milk is so strange that scientists say we shouldn’t really call lactose intolerance a disease, because that presumes it’s abnormal, instead, they call it lactase persistence, indicating what’s really weird is the ability to continue to drink milk.
There’s been a lot of research over the past decade looking at the genetic mutation that allows this subset of humanity to stay milk drinkers into adulthood.
A long-held theory was that the mutation showed up first in Northern Europe, where people got less vitamin D from the sun and therefore did better if they could also get the crucial hormone (it’s not really a vitamin at all) from milk.
But now a group at University College London has shown that the mutation actually appeared about 7, 500 years ago in dairy farmers who lived in a region between the central Balkans and central Europe, in what was known as the Funnel Beaker culture.
The paper was published this week in PLOS Computational Biology.
The researchers used a computer to model the spread of lactase persistence, dairy farming, other food gathering practices and genes in Europe.
Today, the highest proportion of people with lactase persistence live in Northwest Europe, especially the Netherlands, Ireland and Scandinavia. But the computer model suggests that dairy farmers carrying this gene variant probably originated in central Europe and then spread more widely and rapidly than non-dairying groups.
Author Mark Thomas of University College London’s dept of Genetics, Evolution and Environment says, "In Europe, a single genetic change.., is strongly associated with lactase persistence and appears to have people with it a big survival advantage. "
The European mutation is different from several lactase persistence genes associated with small populations of African peoples who historically have been cattle herders.
Researchers at the University of Mary land identified one such mutation among Nilo-Saharan-speaking peoples in Kenya and Tanzania. That mutation seems to have arisen between 2,700 to 6, 800 years ago. Two other mutations have been found among the Beja people of northeastern Sudan and tribes of the same language family in northern Kenya.
According to the third sentence of Paragraph 3, which of the following items is INCORRECT?
选项
A、Anaphylaxis may cause people to die.
B、Eggs can damage all the allergic individuals’ immune system.
C、One who is allergic to gluten can not eat corn.
D、Tuna may cause a person who is allergic to fish to di
答案
B
解析
第三段最后一句指出,鸡蛋等食物可能对过敏体质的人造成严重破坏,并没有说人人都是如此。B项错误。
转载请注明原文地址:https://kaotiyun.com/show/XDua777K
本试题收录于:
翻译硕士(翻译硕士英语)题库专业硕士分类
0
翻译硕士(翻译硕士英语)
专业硕士
相关试题推荐
Legacy—supportagreement
InternationalMonetaryFund
public-privatepartnership
“HehasaservantcalledFriday.”“he”inthequotedsentenceisacharacterin________.
中国国际进口博览会(ChinaInternationalImportExpo,简称CIIE)。2017年5月,习近平主席在“一带一路”国际合作【R31】________上宣布,中国将从2018年起举办中国国际进口博览会。2018年
中非合作论坛(ForumonChina-AfricaCooperation,简称FOCAC),是中华人民共和国和非洲国家之间在南南合作范畴内的集体对话机制,成立于2000。论坛的宗旨是平等【R21】________、增进了解、扩大【R22】_____
Theeyetendstoseedistanceas______.Inpainting,thisissometimescalled"thevanishingpoint".
Notingthemurdervictim’sflaccidmusculatureandpear-likefigure,shededucedthattheunfortunatefollowhadearnedhislivi
Iregret______youthatyourapplicationhasbeenrefused.
Recently,Joe,aforeignEnglishteacherinChina,saidtome,"Ifeeldazedanddisoriented;mystudentshereareunusuallyqui
随机试题
运动拇指的肌有哪些?
Doctorssayangercanbeanextremelydamagingemotion,unlessyoulearnhowtodealwithit.Theywarnthatangryhostilefeeli
龋病易感人群的定义是
具有致痛作用的炎症介质是
患者,男性,40岁。因外伤需急诊进行胆总管探查术,需要一根“T”形管,最佳的消毒方法是()
下列项目中,不能用于支付股利的有()。
表3-1-2、表3-1-3是某公司提供的某销售经理的绩效考核结果。注:5—优、4—良、3—股、2—较差、1—差。请依据表3-1-2的数据评价该销售经理的业绩。
根据心理辅导的目标,可以将心理辅导分为调适性辅导和()。
联网的各个计算机共享一个公共通信信道,当一台计算机发送消息时,所有其他计算机都能“收听”到此消息。这种网络称为______网络。
A、Thebusdoesn’tcomeontime.B、Heforgetstosetthealarmclock.C、Thealarmclockgoeswrong.D、Itrainedheavilythismorn
最新回复
(
0
)