3 - 4 - Week 3A - 4 Analysis of Skeletal Remains I (08 29), kryminalistyka, introduction to forensic science
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[MUSIC][MUSIC]Ultimately the body is going to turn intoa skeleton,and once it's a skeleton, it's verydifficult to get good information,because bones, after all, are bones.One test that can be done is to look atfluorescence.Fresh bone will fluoresce under UV light.Old bone, maybe more than a hundred yearsold bone, will no longer fluoresce.And this is very useful because if bonesturn outto be more than a hundred years old, thenyoucan be pretty safe in assuming that anyoneassociated withthat event is also going to be dead bythis time.You can do some analysis to get some moreinformation,and what we can do is use techniques ofelemental analysis to measurethe level of specific elements in the bone,and this can enlighten us a little more.This is typically called FUN analysisafter three elements fluorine, uranium andnitrogen.Now, fresh bone contains proteins.All proteins contain the element nitrogen,and in freshbone, if you analyze it, you will find thatbone is about 4% nitrogen by weight.However, let's suppose the body is in agrave or somewhereexposed. The proteins in those bones willgradually break down with time,but as the protein molecules break down,the nitrogencontaining compounds will diffuse out ofthe boneinto the environment and be lost, whichmeansthat the bone nitrogen content willdecrease with age.[BLANK_AUDIO]Now, let's turn to the other two elements,fluorine and uranium.These two elements are not naturallypresent in bone,so the content of these two elements infresh bone is 0%.There shouldn't be any fluorine or uraniumin your bones.Now, suppose those bones are buried in anarea where thegroundwater contains appreciable amountsof those elements.Okay, they would be leached from the localrocks,then the bones will absorb those elementsfrom the environment,and that means that the concentration offluorine and uranium will increase withtime.Now, you cannot use this as a kind ofclock to determine time of death,because the absorption of these elementsdependson their presence in the localenvironment.So if that body is in a place where thelocal geochemistry means there is nouranium, then of course it will not absorbany uranium however long you leave it.But if it's in an area where there isuranium naturally presentas a trace mineral in the rocks, then youwill get uranium absorption.So you can't use it as a clock, but youcan use it to compare two bones from thesame place.And if those two bones have been in thesame place for the same length of time,the same number of centuries maybe, thentheyshould have the same amount of uranium andfluorine.Here's an example where this kind ofanalysis proved critical,and this is the story of Piltdown Man.If we go back about a hundred years or alittle bit more,one of the great scientific challenges wasfinding theancestors, our own ancestors, theancestors of homosapiens.Now, the Germans had found the remains ofancient humanoids,and this is Neanderthal Man.The French had found the remains ofancient humanoidsas well, and this is Cro-Magnon Man, andsincethen of course, we also have Peking ManandJava Man, and all the discoveries in EastAfrica.But 100 years ago, British paleontologistswere very disappointed because they hadnot been able to find any ancient humanoidremains anywhere in Britain.So, they have nothing to compare with theremains found by the Germans and theFrench.Well, one dig that was going on was ata place called Piltdown, it's a little wayoutside London,and this was during the period 1912 to1915.And alongside many, many bones ofprehistoric animals,they also found two fragments of humanoidbone,and they claimed that these wereapproximately 500,000 years old.And so of course, they went to theNaturalHistory Museum in London and they weredisplayed in Prideaux Place.Now, what they found was two fragmentsof bone,and you can see the reconstruction in thispicture here.What they found is the two dark parts.You can see a skull fragment,and you can see a jaw fragment.And when you look at these fragments, youconclude thatthe skull fragment is very similar to amodern humanwhereas the jaw fragment is more similarto a modern ape,which indicates that in evolutionaryterms, our brain,our brain cage evolved before our jawevolved.And this finding was never completelyaccepted by the community, becausethe more favoured theory was that the jawevolved in advance of the brain.Nevertheless, those bone fragments werethere inthe Natural History Museum until the late1940s.By the late 1940s, chemical techniques hadimproved a lot, and someone hadthe courage to go to these bone fragmentsand do a little bit of chemical analysis.In fact, he analyzed them for fluorine andnitrogen,and this is what they found. The skullfragment turned out to be 0.2%fluorine, whereas the jaw fragment hadessentiallyno detectable fluorine or almost nofluorine.That means that the two pieces of bone hadnot beenin that site at Piltdown for the samelength of time,therefore they could not come from thesameindividual, they had to come fromdifferent individuals.What's more, the jaw fragment turned outto contain almost 4% nitrogen,which meant that the jaw fragment must beessentially a modern piece of bone.Well, it turned out that that jawfragment actually had been taken from amodern orang-utan, whereas the skullfragment washuman, and it was a few centuries old.And it was a hoax -someone had acquired these two bonefragments,had chemically dyed them so that there'sthe dark colour that you see in thepicture and therefore look old,and that person had placed them in theexcavationso that they would be found by thepaleontologists.Well, it's never been proved who did it.There are suspicions about who might havedone it,but of course, after this length of timeit's never been proved.The Piltdown Man stands as one of the mostfamous examples of a scientific fraud,but it's a scientific fraud that's beenexposed by chemical analysis.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]
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[MUSIC][MUSIC]Ultimately the body is going to turn intoa skeleton,and once it's a skeleton, it's verydifficult to get good information,because bones, after all, are bones.One test that can be done is to look atfluorescence.Fresh bone will fluoresce under UV light.Old bone, maybe more than a hundred yearsold bone, will no longer fluoresce.And this is very useful because if bonesturn outto be more than a hundred years old, thenyoucan be pretty safe in assuming that anyoneassociated withthat event is also going to be dead bythis time.You can do some analysis to get some moreinformation,and what we can do is use techniques ofelemental analysis to measurethe level of specific elements in the bone,and this can enlighten us a little more.This is typically called FUN analysisafter three elements fluorine, uranium andnitrogen.Now, fresh bone contains proteins.All proteins contain the element nitrogen,and in freshbone, if you analyze it, you will find thatbone is about 4% nitrogen by weight.However, let's suppose the body is in agrave or somewhereexposed. The proteins in those bones willgradually break down with time,but as the protein molecules break down,the nitrogencontaining compounds will diffuse out ofthe boneinto the environment and be lost, whichmeansthat the bone nitrogen content willdecrease with age.[BLANK_AUDIO]Now, let's turn to the other two elements,fluorine and uranium.These two elements are not naturallypresent in bone,so the content of these two elements infresh bone is 0%.There shouldn't be any fluorine or uraniumin your bones.Now, suppose those bones are buried in anarea where thegroundwater contains appreciable amountsof those elements.Okay, they would be leached from the localrocks,then the bones will absorb those elementsfrom the environment,and that means that the concentration offluorine and uranium will increase withtime.Now, you cannot use this as a kind ofclock to determine time of death,because the absorption of these elementsdependson their presence in the localenvironment.So if that body is in a place where thelocal geochemistry means there is nouranium, then of course it will not absorbany uranium however long you leave it.But if it's in an area where there isuranium naturally presentas a trace mineral in the rocks, then youwill get uranium absorption.So you can't use it as a clock, but youcan use it to compare two bones from thesame place.And if those two bones have been in thesame place for the same length of time,the same number of centuries maybe, thentheyshould have the same amount of uranium andfluorine.Here's an example where this kind ofanalysis proved critical,and this is the story of Piltdown Man.If we go back about a hundred years or alittle bit more,one of the great scientific challenges wasfinding theancestors, our own ancestors, theancestors of homosapiens.Now, the Germans had found the remains ofancient humanoids,and this is Neanderthal Man.The French had found the remains ofancient humanoidsas well, and this is Cro-Magnon Man, andsincethen of course, we also have Peking ManandJava Man, and all the discoveries in EastAfrica.But 100 years ago, British paleontologistswere very disappointed because they hadnot been able to find any ancient humanoidremains anywhere in Britain.So, they have nothing to compare with theremains found by the Germans and theFrench.Well, one dig that was going on was ata place called Piltdown, it's a little wayoutside London,and this was during the period 1912 to1915.And alongside many, many bones ofprehistoric animals,they also found two fragments of humanoidbone,and they claimed that these wereapproximately 500,000 years old.And so of course, they went to theNaturalHistory Museum in London and they weredisplayed in Prideaux Place.Now, what they found was two fragmentsof bone,and you can see the reconstruction in thispicture here.What they found is the two dark parts.You can see a skull fragment,and you can see a jaw fragment.And when you look at these fragments, youconclude thatthe skull fragment is very similar to amodern humanwhereas the jaw fragment is more similarto a modern ape,which indicates that in evolutionaryterms, our brain,our brain cage evolved before our jawevolved.And this finding was never completelyaccepted by the community, becausethe more favoured theory was that the jawevolved in advance of the brain.Nevertheless, those bone fragments werethere inthe Natural History Museum until the late1940s.By the late 1940s, chemical techniques hadimproved a lot, and someone hadthe courage to go to these bone fragmentsand do a little bit of chemical analysis.In fact, he analyzed them for fluorine andnitrogen,and this is what they found. The skullfragment turned out to be 0.2%fluorine, whereas the jaw fragment hadessentiallyno detectable fluorine or almost nofluorine.That means that the two pieces of bone hadnot beenin that site at Piltdown for the samelength of time,therefore they could not come from thesameindividual, they had to come fromdifferent individuals.What's more, the jaw fragment turned outto contain almost 4% nitrogen,which meant that the jaw fragment must beessentially a modern piece of bone.Well, it turned out that that jawfragment actually had been taken from amodern orang-utan, whereas the skullfragment washuman, and it was a few centuries old.And it was a hoax -someone had acquired these two bonefragments,had chemically dyed them so that there'sthe dark colour that you see in thepicture and therefore look old,and that person had placed them in theexcavationso that they would be found by thepaleontologists.Well, it's never been proved who did it.There are suspicions about who might havedone it,but of course, after this length of timeit's never been proved.The Piltdown Man stands as one of the mostfamous examples of a scientific fraud,but it's a scientific fraud that's beenexposed by chemical analysis.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]