雅思阅读第083套P1-Wolves, dogs and humans

Wolves, dogs and humans

There is no doubt that dogs are the oldest of all species tamed by humans and their domestication was based on a mutually beneficial relationship with man. The conventional view is that the domestication of wolves began between 10,000 and 20,000 years ago. However, a recent ground-breaking paper by a group of international geneticists has pushed this date back by a factor of 10. Led by Dr. Robert Wayne, at the University of California, Los Angeles, the team showed that all dog breeds had only one ancestor, the wolf. They did this by analysing the genetic history through the DINA of 162 wolves from around the world and 140 domestic dogs representing 67 breeds. The research also confirms, for the first time, that dogs are descended only from wolves and do not share DNA with coyotes or jackals. The fact that our companionship with dogs now appears to go back at least 100,000 years means that this partnership may have played an important part in the development of human hunting techniques that developed 70,000 to 90,000 years ago. It also may even have affected the brain development in both species.

The Australian veterinarian David Paxton suggests that in that period of first contact, people did not so much domesticate wolves as wolves domesticated people. Wolves may have started living at the edge of human settlements as scavengers, eating scraps of food and waste. Some learned to live with human beings in a mutually helpful way and gradually evolved into dogs. At the very least, they would have protected human settlements, and given warnings by barking at anything approaching. The wolves that evolved into dogs have been enormously successful in evolutionary terms. They are found everywhere in the inhabited world, hundreds of millions of them. The descendants of the wolves that remained wolves are now sparsely distributed, often in endangered populations.

In return for companionship and food, the early ancestor of the dog assisted humans in tracking, hunting, guarding and a variety of other activities. Eventually humans began to selectively breed these animals for specific traits. Physical characteristics changed and individual breeds began to take shape. As humans wandered across Asia and Europe, they took their dogs along, using them for additional tasks and further breeding them for selected qualities that would better enable them to perform specific duties.

According to Dr. Colin Groves, of the Department of Archaeology and Anthropology at Australian National University, early humans came to rely on dogs’ keen ability to hear, smell and see – allowing certain areas of the human brain to shrink in size relative to oilier areas. ‘Dogs acted as human’s alarm systems, trackers and hunting aids, garbage disposal facilities, hot-water bottles and children’s guardians and playmates. Humans provided dogs with food and security. This symbiotic relationship was stable for over 100,000 years and intensified into mutual domestication,’ said Dr. Groves. In his opinion, humans domesticated dogs and dogs domesticated humans.

Dr. Groves repealed an assertion made as early as 1914 that humans have some of the same physical characteristics as domesticated animals, the most notable being decreased brain size. The horse experienced a 16 percent reduction in brain size after domestication while pigs’ brains shrank by as much as 34 percent. The estimated brain-size reduction in domesticated dogs varies from 30 percent to 10 percent. Only in the last decade have archaeologists uncovered enough fossil evidence to establish that brain capacity in humans declined in Europe and Africa by at least 10 percent beginning about 10,000 years ago. Dr. Groves believes this reduction may have taken place as the relationship between humans and dogs intensified. The close interaction between the two species allowed for the diminishing of certain human brain functions like smell and hearing.

SECTION 1: QUESTIONS 1-14

Questions 1-5

Do the following statements agree with the views of the writer of the passage?

Write:

1 _________________ The co-existence of wolves and humans began 10,000 years ago.

2 _________________ Dogs, wolves, jackals and coyotes share a common ancestor.

3 _________________ Wolves are a protected species in most parts of the world.

4 _________________ Dogs evolved from wolves which chose to live with humans.

5 _________________ Dogs probably influenced the development of human hunting skills.

Questions 6-8

Choose the correct letter A-D.

6How do we know that dogs have been more successful in evolutionary terms than wolves?

ADogs can be trained more easily than wolves.

BWolves are stronger than dogs.

CHumans prefer dogs to wolves.

DThere are more dogs than wolves today.

7As a result of domestication, the size of the human brain has …

Aincreased.

Bdecreased

Cstayed the same.

Dbecome more complex.

8What can we infer from the studies of brain size and domestication?

ADomestic life is less demanding than surviving in the wild.

BAnimals like living with humans.

CDomestication has made animals physically weaker.

DPigs are less intelligent than dogs.

Question 9

Choose TWO WORDS from the passage for the answer.

There are many different types of dogs today, because, in early times humans began to 9 _________________ their animals for the characteristics they wanted.

Questions 10-14

Match one of the researchers (A-C) to each of the findings (10-14) below.