- UID
- 538688
- 在线时间
- 小时
- 注册时间
- 2010-6-8
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
非常象。方便g友阅读
Rodent Bones of Contention
Rats caught a free ride to New Zealand when they hopped aboardthe boats of early Polynesian explorers. Now, their ancient bonesmay help pinpoint when humans first set foot on the island.Carbon-dating of bones from the rodents indicates that peoplereached New Zealand around 1280 or later, rejecting previousresearch that suggested humans may have landed there more than 1400years earlier.
Although most anthropologists think that humans first arrived inNew Zealand around 1250 to 1300, a minority holds that people mighthave set foot on the island as early as 200 B.C.E. That conclusionis based on 1996 research that carbon-dated bones of rats, whichare thought to have been brought to New Zealand by humans either asstowaways or for food. But this study has been controversialbecause there's no evidence of human settlements at that time. Somecritics have suggested that the carbon dates were due to a laberror in preparing the bones.
To help clear up the confusion, a team led by Janet Wilmshurst,a paleoecologist at environmental research organization LandcareResearch in Lincoln, New Zealand, used a different preparationtechnique that is thought to be more accurate. The researchersobtained 17 bones from the two excavation sites where the oldestrat remains had been found. Carbon-dating with the improved methodindicated that the new bones were from 1280 or later. When theresearchers tried the new technique on some of the bones from theprevious study, all of them dated to later than 1280, indicatingthat the earlier research was flawed. The researchers nextcarbon-dated ancient seeds that the rats had gnawed and that camefrom one of the excavation sites. The results gave a date of 1290or later, confirming that humans did not arrive until 1280 at theearliest, the researchers report in the 3 June issue of theProceedings of the National Academy of Sciences.
Ian Smith, an anthropologist at the University of Otago in NewZealand, says the finding "provides convincing evidence against theassertion that either rats or people reached New Zealand prior tothe 13th century A.D." He adds that the later arrival indicatesthat humans' devastating impact on New Zealand, which has includeddeforestation and the extinction of birds and marine mammals,happened in only 600 years, versus more than 2000 years if theinitial bone dating had been confirmed.
David Lowe, a soil scientist at the University of Waikato inHamilton, New Zealand, says the findings also indicate that "thedestruction caused by the rats in New Zealand has been pronouncedand very fast indeed." The rats wiped out several species,including some birds and frogs. Wilmshurst adds that the speed ofdestruction "makes the risk to currently declining populations ofrat-sensitive species more pressing as they could be diminishingfaster than previously assumed."
出处: http://news.sciencemag.org/sciencenow/2008/06/02-02.html
|
|
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2013-5-27 02:57:14
收藏
收藏
发表于 2013-5-27 09:14:56
楼主