英语听力：探索发现 2013-02-13 猛玛象进城记 Mammoths to Manhattan—7

 ...and may trace their ancestry¹ all the way back to the first dogs to enter North America. The Carolina dogs are pack animals with a strick hierarchy² topped by an alpha male. Like most wild dogs, they hunt in groups. But many of the kills they make are small. Rabbits and small rodents³ make up a large part of their diet in what can become a collective feeding frenzy⁴. At the end of the ice age, these dogs' ancestors also had access to other sources of food. They may have hung around the camps of early native people, scavenging the scraps⁵. 

 

But although they lived on the fringes of human society, the early wild dogs were certainly not pets. Exactly when they arrived in North America is still uncertain. But it's likely that they slipped in after the extinction⁶ of the ice age beasts during a time of massive change. 

 

Eventually the continent became more settled. Over the next few thousand years, people adapted to the many regions of the continent and their varying lifestyles were shaped by the landscape they lived in. 

 

Then more than 14,000 years after the first people set foot in North America, another wave of immigrants brought changes that would have a dramatic impact on the landscape and wildlife of the new world.

1 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

2 hierarchy   

n.等级制度；统治集团，领导层

参考例句：

• There is a rigid hierarchy of power in that country.那个国家有一套严密的权力等级制度。
• She's high up in the management hierarchy.她在管理阶层中地位很高。

3 rodents   

n.啮齿目动物( rodent的名词复数 )

参考例句：

• Rodents carry diseases and are generally regarded as pests. 啮齿目动物传播疾病，常被当作害虫对待。 来自《简明英汉词典》
• Some wild rodents in Africa also harbor the virus. 在非洲，有些野生啮齿动物也是储毒者。 来自辞典例句

4 frenzy   

n.疯狂，狂热，极度的激动

参考例句：

• He was able to work the young students up into a frenzy.他能激起青年学生的狂热。
• They were singing in a frenzy of joy.他们欣喜若狂地高声歌唱。

5 scraps   

油渣

参考例句：

• Don't litter up the floor with scraps of paper. 不要在地板上乱扔纸屑。
• A patchwork quilt is a good way of using up scraps of material. 做杂拼花布棉被是利用零碎布料的好办法。

6 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。