关闭图标
log图标

toefl.viplgw.cn

  • 使用手机注册
  • 使用邮箱注册
  • 手机号不能为空!

    验证码不能为空!

    用户名不能为空!

    密码不能为空!

  • 邮箱不能为空!

    验证码不能为空!

    用户名不能为空!

    密码不能为空!

已有账号? 登录到雷哥托福
关闭图标
log图标
  • 使用手机找回密码
  • 使用邮箱找回密码
  • 手机号不能为空!

    验证码不能为空!

    密码不能为空!

  • 邮箱不能为空!

    验证码不能为空!

    密码不能为空!

又想起来了
加入生词本

listen

英['lɪs(ə)n] 美['lɪsn]
vi. 听,倾听;听从,听信
n. 听,倾听

已添加
×

我要举报草莓小菇凉评论

用户头像
草莓小菇凉:说的非常好,十分有道理,棒棒棒!

06-08 15:44:55

请选择举报类型:

举报电话:400 1816 180    举报QQ:2095453331
×
logo图标
分享到雷哥托福

分享成功图标分享成功

邀请名师点评成功,管理员正在安排老师进行点评。

继续做题 返回首页
支付雷豆失败图标 雷豆余额不足 购买雷豆 返回
报告题目错误
请选择错误类型:
请描述一下这个错误:

取消

文章结构

Official 24-L3 .Megafauna 点击收藏

标准

  • 高音
  • 静音
  • 句子
    精听
  • 全文
    精听
  • 听写
    模式
  • 点击查看本句

    听写本句 再播一遍 下一句
  • 点击查看全文

    再播一遍本文

    Listen to part of lecture in an archeology class.

    Between 11000 - 10000 B.C.E., North America was populated by a wide variety of great beasts, like mammoth, and mastodons, both elephant-like creatures with big tusks, and camels, giant slots, the list goes on.

    By about 10000 B.C.E., all those giant creatures, the Megfauna of North America were gone.

    We do not know exactly what happened to them, but there are some theories.

    One theory is that they were hunted to extinction by humans.

    The humans who coexist with these giant species in North America at that time were what we today called the Clovis people.

    And there is a Clovis site in a valley in Southern California where the remains of thirteen mammoths were found.

    And spear points, tools for processing meat, and fire places.

    That would appear to be some pretty compelling evidence.

    Mammoth bones have also been found at some other Clovis sites.

    But then at other Clevis sites, there is also a lot of evidence that the Clevis people mostly gather plants and hunted small games, like rabbits and wild turkeys.

    Also there are several places in North America Where you have natural accumulations of mammoth bones that looks very similar to the accumulations at the Clevis site, except there is no human debris, where the mammoth almost certainly died as a result of some kind of natural disaster.

    So I think it is quite likely that those 13 mammoth in Southern California also died of nature causes, and that Clevis people simply took advantage of the situation.

    Um... OK. That is the hunting theory.

    Now let's look at another theory, uh, an alternative to the hunting theory, the climate change theory.

    At around of 11500 B.C.E., the world was coming out of the ice age.

    And with that came increased seasonality, that is, the summers became warmer, and the winters actually became colder.

    This extreme shifts would have put a lot of stress on the bodies of animals that were used to a more moderate range of temperatures.

    But the most important impact of this increased seasonality may very well have been its effect on the distribution of plants.

    Today we take for granted that there are horizontal bands of plant communities.

    In the far north, it is tundra, which gives way to the forest as you move southward.

    And even farther south, grasslands take over.

    But during the ice age, these plant communities actually grew together, mixed with one another.

    So ice age animals had access to many different types of plants, different types of food.

    But when the seasons became more distinct, the plant communities were pulled apart, that meant, that in any given area, there was less plant diversity.

    And as a result, so the theory goes, the Ice Age animals that depended on plants diversity couldn't survive.

    And the greatest beasts were the ones that needed the most diversity in their diet.

    Again, we have what at first seems like a pretty attractive theory, but then, how do you explain the fact that this has happened before?

    You know, global cooling followed by global warming, and there was no extinction then.

    Uh, you know, I recently read an interesting article about an archeologist who tried to solve this puzzle with the help of his computer.

    What he did was, he wrote a computer program to simulate what would happen to mammoth under certain conditions.

    Em, say for example, there is a drought for a couple of decades, or hunters are killing of 5 percent of the population and so on.

    One thing he found was that humans did not necessarily have to kill these animals in great numbers in order to nudge them toward the extinction.

    That's because very large animals have a slow rate of reproduction, so all you have to do is remove a few young females from the herds and you can, fairly quickly, significantly reduce the population.

    And then he came up with a scenario that combined some hunting by humans with some environmental stress, and... bang.

    The simulated mammoth were extinct within decades.

    So it seems the mixture of hunting and climate change is a likely scenario.

    Uh, Of course, computer simulations are not a substitute for hard evidence.

    • special
    ☞查看答案 再播一遍

联系雷哥托福

全国免费咨询热线:400 1816 180

  • 上海(总部)
  • 北京
  • 成都
  • 杭州
  • 武汉
  • 南京
  • 广州
  • 西安
  • 重庆
  • 深圳
  • 上海(总部)服务中心

    电话:400 1816 180

    地址:上海市徐汇区文定路218号德必徐家汇WE艺术湾B座205

    公交路线:76路、93路、138路宜山路蒲汇塘路站;205路、732路、754路南丹路宜山路站;205路、754路、830路南丹路文定路站等

    地铁路线:地铁3号线、4号线宜山路站出站470m;地铁1号线、4号线上海体育馆站出站600m。

  • 北京服务中心

    电话:400 1816 180

    地址:北京市朝阳区雅宝路7号 E园EPARK大厦508

    公交路线:乘坐公交44路外环;58路;139路;特12路外环;特2路;夜20路外环到雅宝路公交站 下车,走140米即可达到。

    地铁路线:乘坐地铁1号线、2号线到建国门站(A出口)步行1000米即可到达;乘坐地铁2号线、6号线到朝阳门站(A出口)步行1200米即可到达雅宝路7号 E园EPARK大厦。

  • 成都服务中心

    电话:400 1816 180

    地址:成都市锦江区总府路31号Z31六楼(皇冠假日酒店旁)

    公交路线:乘坐58路、98路、锦城观光3号线、熊猫快线5号线在春熙路步行街北站下 步行约281米。

    地铁路线:乘坐地铁2号线或者3号线到春熙路C口下,步行约982米

  • 杭州服务中心

    电话:400 1816 180

    地址:杭州市江干区江锦路159号 平安金融中心B座8楼

    公交路线:901路、105路环线、106路环线、9M路:富春路民心路口站 176路:市民中心北大门站,市民中心西大门站

    地铁路线:号线钱江路站;4号线钱江路,江锦路

  • 武汉服务中心

    电话:400 1816 180

    地址:武汉市珞瑜路光谷世界城广场写字楼1栋1单元14层11421室

    公交路线:乘坐18路,25路,340路,510路,518路,521路等公交车到珞瑜路湖北省中医院站下车

    地铁路线:乘坐地铁2号线至珞雄路A口出,往湖北省中医院光谷院区方向步行50米至世界城广场写字楼

  • 南京服务中心

    电话:400 1816 180

    地址: 南京市秦淮区中山东路532号金蝶科技园 H1幢308号(林客社 内)

    公交路线:5路 34路 34路区间 36路 55路 59路 y5路夜间 17路 65路 115路 118路 y17路夜间

    地铁路线:地铁2号线明故宫站1号口出,向东200米

  • 广州服务中心

    电话:400 1816 180

    地址:广州市天河区体育西路103号维多利广场B座26楼K15

    公交路线:11,18,20,230,278,293,45,583,669,886冼村路中站下。 194,40,777,778,90,观光2路花城广场路站下。

    地铁路线:乘坐地铁APM线至花城大道站下B口出,步行约500米即可到达保利威座大厦北塔。

  • 西安服务中心

    电话:400 1816 180

    地址:西安市莲湖区北大街西华门十字西南角78号嘉会广场C座4层B021号

    公交路线:4路、12路、26路、36路、37路、229路、游7钟楼北站;15路、16路、32路、102路、182路、236路、286路西华门站。

    地铁路线:地铁二号线钟楼站150米;地铁一号线/二号线北大街站700米。

  • 重庆服务中心

    电话:400 1816 180

    地址:重庆市渝中区邹容路68号大都会广场16楼1603-1604室

    公交路线:401、135、114、111、401、151、862、181、262、105、866、153、466

    地铁路线:2号线临江门站500米、1号线小什字站500米、6号线小什字站500米。

  • 深圳服务中心

    电话:400 1816 180

    地址:深圳市罗湖区书城路都市名园B栋5楼B区(只接受预约拜访)

    公交路线:101路 10路 12路 203路 214路 215路 223路 29路 3路 85路 M112路 M191路 M192路 N3路 P100路(定制公交请预约) 高快巴士200号线 高快巴士20路 高快巴士863号线到地王大厦下,步行431米即可到达。

    地铁路线:乘坐1号线/罗宝线/2号线/蛇口线到大剧院(E口)出,步行498米即可到达都市名园B栋

预约托福考试规划师