Don't wash those fossils!

Standard museum practice can wash away DNA.

1.Washing, brushing and varnishing fossils — all standard conservation treatments used by many fossil hunters and museum curators alike — vastly reduces the chances of recovering ancient DNA.

2.Instead, excavators should be handling at least some of their bounty with gloves, and freezing samples as they are found, dirt and all, concludes a paper in the Proceedings of the National Academy of Sciences today.

3.Although many palaeontologists know anecdotally that this is the best way to up the odds of extracting good DNA, Eva-Maria Geigl of the Jacques Monod Institute in Paris, France, and her colleagues have now shown just how important conservation practices can be.This information, they say, needs to be hammered home among the people who are actually out in the field digging up bones.

4.Geigl and her colleagues looked at 3,200-year-old fossil bones belonging to a single individual of an extinct cattle species, called an aurochs.The fossils were dug up at a site in France at two different times — either in 1947, and stored in a museum collection, or in 2004, and conserved in sterile conditions at -20 oC.

5.The team's attempts to extract DNA from the 1947 bones all failed.The newly excavated fossils, however, all yielded DNA.

6.Because the bones had been buried for the same amount of time, and in the same conditions, the conservation method had to be to blame says Geigl."As much DNA was degraded in these 57 years as in the 3,200 years before," she says.

Wash in, wash out

7.Because many palaeontologists base their work on the shape of fossils alone, their methods of conservation are not designed to preserve DNA, Geigl explains.

8.The biggest problem is how they are cleaned.Fossils are often washed together on-site in a large bath, which can allow water — and contaminants in the form of contemporary DNA — to permeate into the porous bones."Not only is the authentic DNA getting washed out, but contamination is getting washed in," says Geigl.

9.Most ancient DNA specialists know this already, says Hendrik Poinar, an evolutionary geneticist at McMaster University in Ontario, Canada.But that doesn't mean that best practice has become widespread among those who actually find the fossils.

10.Getting hold of fossils that have been preserved with their DNA in mind relies on close relationships between lab-based geneticists and the excavators, says palaeogeneticist Svante P bo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.And that only occurs in exceptional cases, he says.

11.P bo's team, which has been sequencing Neanderthal DNA, continually faces these problems."When you want to study ancient human and Neanderthal remains, there's a big issue of contamination with contemporary human DNA," he says.

12.This doesn't mean that all museum specimens are fatally flawed, notes P bo.The Neanderthal fossils that were recently sequenced in his own lab, for example, had been part of a museum collection treated in the traditional way.But P bo is keen to see samples of fossils from every major find preserved in line with Geigl's recommendations — just in case.

Warm and wet

13.Geigl herself believes that, with cooperation between bench and field researchers, preserving fossils properly could open up avenues of discovery that have long been assumed closed.

14.Much human cultural development took place in temperate regions.DNA does not survive well in warm environments in the first place, and can vanish when fossils are washed and treated.For this reason, Geigl says, most ancient DNA studies have been done on permafrost samples, such as the woolly mammoth, or on remains sheltered from the elements in cold caves — including cave bear and Neanderthal fossils.

15.Better conservation methods, and a focus on fresh fossils, could boost DNA extraction from more delicate specimens, says Geigl.And that could shed more light on the story of human evolution.

(640 words nature )

Glossary

Palaeontologists 古生物学家

Aurochs 欧洲野牛

Neanderthal (人类学)尼安德特人，旧石器时代的古人类。

Permafrost (地理)永冻层

Questions 1-6

Answer the following questions by using NO MORE THAN THREE WORDS for each answer.

1.How did people traditionally treat fossils?

2.What suggestions do Geigl and her colleagues give on what should be done when fossils are found?

3.What problems may be posed if fossil bones are washed on-site? Name ONE.

4.What characteristic do fossil bones have to make them susceptible to be contaminated with contemporary DNA when they are washed?

5.What could be better understood when conservation treatments are improved?

6.The passage mentioned several animal species studied by researchers.How many of them are mentioned?

Questions 7-11

Do the following statements agree with the information given in the passage? Please write TRUE if the statement agrees with the writer FALSE if the statement does not agree with the writer NOT GIVEN if there is no information about this in the passage.

7.In their paper published in the Proceedings of the National Academy of Sciences，Geigl and her colleagues have shown what conservation practices should be followed to preserve ancient DNA.

8.The fossil bones that Geigl and her colleagues studied are all from the same aurochs.

9.Geneticists don't have to work on site.

10.Only newly excavated fossil bones using new conservation methods suggested by Geigl and her colleagues contain ancient DNA.

11.Paabo is still worried about the potential problems caused by treatments of fossils in traditional way.

Questions 12-13

Complete the following the statements by choosing letter A-D for each answer.

12.“This information” in paragraph 3 indicates:

[A] It is critical to follow proper practices in preserving ancient DNA.

[B] The best way of getting good DNA is to handle fossils with gloves.

[C] Fossil hunters should wear home-made hammers while digging up bones.

[D] Many palaeontologists know how one should do in treating fossils.

13.The study conducted by Geigl and her colleagues suggests:

[A] the fact that ancient DNA can not be recovered from fossil bones excavated in the past.

[B] the correlation between the amount of burying time and that of the recovered DNA.

[C] the pace at which DNA degrades.

[D] the correlation between conservation practices and degradation of DNA.

In the earliest stages of man's development he had nomore need of money than animals have.He was content with very simple forms of shelter,made his own rough tools and weapons and could provide food and clothing for himself and his family from natural materials around him.As he became more civilized,however,he began to want better shelter,more efficient tools and weapons,and more comfortable and more lasting clothing than could be provided by his own neighborhood or by the work of his own unskilled hands.For these things he had to turn to the skilled people such as smiths,leather workers or carpenters.It was then that the question of payment arose.

At first he got what he wanted by a simple process ofexchange.The smith who had not the time to look after land or cattle was glad to take meat or grain from the farmer inexchange for an axe or a plough.But as more and more goods which had no fixed exchange value came on the market,exchange became too complicated to be satisfactory.Another problem arose when those who made things wanted to get stocks of wood or leather,or iron,but had nothing to offer in exchange until their finished goods were ready. Thus the difficulties of exchange led by degrees to the invention of money.In some countries easily handled things like seeds or shells were given a certain value and the farmer,instead of paying the smith for a new axe by giving him some meat or grain,gave him so many shells.If the smith had any shells left when he had bought his food,he could get stocks of the raw materials of his trade.In some countries quite large things such as cows or camels or even big flat stones were used for trade.Later,pieces of metal,bearing values according to the rarity of the metal and the size of the pieces,or coins were used.Money as we know it had arrived.

1.Exchange of goods became difficult because _________.

A man became more civilized

B smiths began to look after land or cattle in their spare time

C more and more goods which had no fixed exchange alues came to the marker

D farmers hadn't enough grain or meat to provide for

skilled workers

2.Money was not used until _______.

A paper was invented

B people practiced a simple process of exchange

C nothing could be offered in exchangeD the exchange of one thing for another became too complicated

3.The best title for this passage is _____.

A What is money

B What are money's functions.

C The importance of money

D The beginning of money

-----Dad，lookatthebuilding.Itisonfire.

-----Call119____________mobilephonerightnow

To begin with,"muzak"(音乐广播网 )was intended simplyto createasoothing(安慰)atmosphere.Recently,however,it's ecome big business —thanks in part to recentresearch.Dr.Ronald Milliman,an American marketing expert,hasshown that music can boost sales or increase factory roduction by as much as a third.But,it has to be light music.A fast one has no effect atall on sales.Slow music can increase receipts by 38%.This isprobably because shoppers slow down and have more opportunityto spot items they like to buy.Yet,slow music isn't alway sanswer.Dr.Milliman found,for example,that in restaurants slowmusic meant customers took longer to eat their meals,whichreduced overall sales.So restaurants owners might be welladvised to play up-tempo music to keep the customers moving—unless of course,the resulting indigestion leads tocomplaints!

练习：

1.The reason why background music is so popular isthat ______.

A.it can have a powerful effect on those who hear it

B.it can help to create a soothing atmosphere

C.it can boost sales or increase factory production erywhere

D.it can make customers eat their meals quickly

2.Background music means ________.

A.light music that customers enjoy mostB.fast music that makes people move fast

C.slow music that can make customers enjoy their meals

D.the music you are listening to while you are doingomething

3.Restaurant owners complain about background musicbecause ______.

A.it results in indigestion

B.it increases their sales

C.it keeps customers moving

D.it decreases their sales

4.The word"up-tempo music"probably means_____.

A.slow music

B.fast music

C.light music

D.classical music

1There'sadimmerswitchinsidethesunthatcausesitsbrightnesstoriseandfallontimescalesofaround100,000years-exactlythesameperiodasbetweeniceagesonEarth.Sosaysaphysicistwhohascreatedacomputermodelofourstar'score.

2RobertEhrlichofGeorgeMasonUniversityinFairfax,Virginia,modelledtheeffectoftemperaturefluctuationsinthesun'sinterior.Accordingtothestandardview,thetemperatureofthesun'scoreisheldconstantbytheopposingpressuresofgravityandnuclearfusion.However,Ehrlichbelievedthatslightvariationsshouldbepossible.

3HetookashisstartingpointtheworkofAttilaGrandpierreoftheKonkolyObservatoryoftheHungarianAcademyofSciences.In2005,Grandpierreandacollaborator,Gáborágoston,calculatedthatmagneticfieldsinthesun'scorecouldproducesmallinstabilitiesinthesolarplasma.Theseinstabilitieswouldinducelocalisedoscillationsintemperature.

4Ehrlich'smodelshowsthatwhilstmostoftheseoscillationscanceleachotherout,somereinforceoneanotherandbecomelong-livedtemperaturevariations.Thefavouredfrequenciesallowthesun'scoretemperaturetooscillatearounditsaveragetemperatureof13.6millionkelvinincycleslastingeither100,000or41,000years.Ehrlichsaysthatrandominteractionswithinthesun'smagneticfieldcouldflipthefluctuationsfromonecyclelengthtotheother.

5ThesetwotimescalesareinstantlyrecognisabletoanyonefamiliarwithEarth'siceages:forthepastmillionyears,iceageshaveoccurredroughlyevery100,000years.Beforethat,theyoccurredroughlyevery41,000years.

6MostscientistsbelievethattheiceagesaretheresultofsubtlechangesinEarth'sorbit,knownastheMilankovitchcycles.OnesuchcycledescribesthewayEarth'sorbitgraduallychangesshapefromacircletoaslightellipseandbackagainroughlyevery100,000years.ThetheorysaysthisalterstheamountofsolarradiationthatEarthreceives,triggeringtheiceages.However,apersistentproblemwiththistheoryhasbeenitsinabilitytoexplainwhytheiceageschangedfrequencyamillionyearsago.

7"InMilankovitch,thereiscertainlynogoodideawhythefrequencyshouldchangefromonetoanother,"saysNeilEdwards,aclimatologistattheOpenUniversityinMiltonKeynes,UK.NoristhetransitionproblemtheonlyonetheMilankovitchtheoryfaces.EhrlichandothercriticsclaimthatthetemperaturevariationscausedbyMilankovitchcyclesaresimplynotbigenoughtodriveiceages.

8However,EdwardsbelievesthesmallchangesinsolarheatingproducedbyMilankovitchcyclesarethenamplifiedbyfeedbackmechanismsonEarth.Forexample,ifseaicebeginstoformbecauseofaslightcooling,carbondioxidethatwouldotherwisehavefounditswayintotheatmosphereaspartofthecarboncycleislockedintotheice.ThatweakensthegreenhouseeffectandEarthgrowsevencolder.

9AccordingtoEdwards,thereisnolackofsuchmechanisms."Ifyouaddtheireffectstogether,thereismorethanenoughfeedbacktomakeMilankovitchwork,"hesays."Theproblemnowisidentifyingwhichmechanismsareatwork."ThisiswhyscientistslikeEdwardsarenotyetreadytogiveuponthecurrenttheory."Milankovitchcyclesgiveusiceagesroughlywhenweobservethemtohappen.Wecancalculatewhereweareinthecycleandcompareitwithobservation,"hesays."Ican'tseeanywayoftesting[Ehrlich's]ideatoseewhereweareinthetemperatureoscillation."

10Ehrlichconcedesthis."Ifthereisawaytotestthistheoryonthesun,Ican'tthinkofonethatispractical,"hesays.That'sbecausevariationover41,000to100,000yearsistoogradualtobeobserved.However,theremaybeawaytotestitinotherstars:reddwarfs.Theircoresaremuchsmallerthanthatofthesun,andsoEhrlichbelievesthattheoscillationperiodscouldbeshortenoughtobeobserved.Hehasyettocalculatethepreciseperiodortheextentofvariationinbrightnesstobeexpected.

11NigelWeiss,asolarphysicistattheUniversityofCambridge,isfarfromconvinced.HedescribesEhrlich'sclaimsas"utterlyimplausible".EhrlichcountersthatWeiss'sopinionisbasedonthestandardsolarmodel,whichfailstotakeintoaccountthemagneticinstabilitiesthatcausethetemperaturefluctuations.

Questions1-4

CompleteeachofthefollowingstatementswithOneorTwonamesofthescientistsfromtheboxbelow.

WritetheappropriatelettersA-Einboxes1-4onyouranswersheet.

A.AttilaGrandpierre

B.Gáborágoston

C.NeilEdwards

D.NigelWeiss

E.RobertEhrlich

1....claimsthereadimmerswitchinsidethesunthatcausesitsbrightnesstoriseandfallinperiodsaslongasthosebetweeniceagesonEarth.

2....calculatedthattheinternalsolarmagneticfieldscouldproduceinstabilitiesinthesolarplasma.

3....holdsthatMilankovitchcyclescaninducechangesinsolarheatingonEarthandthechangesareamplifiedonEarth.

4....doesn'tbelieveinEhrlich'sviewpointsatall.

Questions5-9

Dothefollowingstatementsagreewiththeinformationgiveninthereadingpassage?

Inboxes5-9onyouranswersheetwrite

TRUEifthestatementistrueaccordingtothepassage

FALSEifthestatementisfalseaccordingtothepassage

NOTGIVENiftheinformationisnotgiveninthepassage

5.Theiceageschangedfrequencyfrom100,000to41,000yearsamillionyearsago.

6.ThesoleproblemthattheMilankovitchtheorycannotsolveistoexplainwhytheiceagefrequencyshouldshiftfromonetoanother.

7.Carbondioxidecanbelockedartificiallyintoseaicetoeliminatethegreenhouseeffect.

8.SomescientistsarenotreadytogiveuptheMilankovitchtheorythoughtheyhaven'tfiguredoutwhichmechanismsamplifythechangesinsolarheating.

9.BothEdwardsandEhrlichbelievethatthereisnopracticalwaytotestwhenthesolartemperatureoscillationbeginsandwhenends.

Questions10-14

Completethenotesbelow.

ChooseonesuitablewordfromtheReadingPassageaboveforeachanswer.

Writeyouranswersinboxes10-14onyouranswersheet.

Thestandardviewassumesthattheopposingpressuresofgravityandnuclearfusionsholdthetemperature...10...inthesun'sinterior,buttheslightchangesintheearth's...11...alterthetemperatureontheearthandcauseiceagesevery100,000years.ABritishscientist,however,challengesthisviewbyclaimingthattheinternalsolarmagnetic...12...caninducethetemperatureoscillationsinthesun'sinterior.Thesun'scoretemperatureoscillatesarounditsaveragetemperaturein...13...lastingeither100,000or41,000years.Andthe...14...interactionswithinthesun'smagneticfieldcouldflipthefluctuationsfromonecyclelengthtotheother,whichexplainswhytheiceageschangedfrequencyamillionyearsago.