Please rate this essay I am going to take exam on 25th August so I have a liittle time to prepare.
The script for reading passage:
[color=green]The Northern Land Bridge
Much archaeological evidence supports the widely held view that the first people to migrate to the American continent entered through a land bridge, which at one time joined Eastern Asia with North America. This land bridge, known as Beringia, was a wide expanse of terrain that emerged from the ocean as the sea levels dropped due to widespread glaciation at the time of the last Ice Age. Groups of humans could have slowly migrated across the grassy tundra of Beringia, feeding on herds of animals or coastal marine life. At the time, much of North America including what is now Canada, would have been covered with thick ice sheets making further movement southward a physical impossibility. At a later period, the ice receded and humans would have been able to traverse an ice-free corridor in a southerly direction, and gradually settle the vast uninhabited continent. The ending of the Ice Age also caused the ocean levels to rise, thus submerging Beringia and isolating the new migrants from peoples on the Asian side. During the next centuries the descendants of the pioneers who crossed Beringia gradually peopled the entire landmass of the Americas. This view of the origins of the first Americans is often known as the Clovis-first theory (named after the site in New Mexico where stone artifacts made by these settlers were first found). Many subsequent finds of Clovis tools demonstrate this culture's extensive penetration throughout the continent.
The script for the listening:
OK, you’ve all read about humans crossing the Beringia landbridge from Asia to the North American continent. Now, ice sheets would have prevented this penetration until about 13,000 years ago, so one could assume the first people entered between 11,000 and 13,000 years ago. That’s the theory, which, however, has recently come under attack. So, let me mention some evidence that seems to undermine the “Clovis-first” idea.
So first, several archaeological sites in the Americas appear older than the Clovis period. Some sites in the eastern United States may be up to 19,000 years old. That’s a long time before Clovis tools were made. In South America, one site suggests the existence of pre-Clovis people as far south as Chile. Dating techniques put this settlement at around 15,000 years old, several thousand years before the first humans are claimed to have entered North America. And it presumably took centuries for humans to migrate that far south. So, we can say that the dates of these finds don’t tally with Clovis first.
Now, another finding which weakens the Clovis-first idea is that some of the oldest remains found don’t look like the remains of Native Americans. They resemble people from the Pacific islands or northern Japan. This could mean that America was colonized by a variety of peoples. This diversity must have been reduced at some point - since modern Native Americans seem to be descended anatomically from Siberian people.
A third problem is that DNA analysis suggests people from Siberia may have migrated to North America about 40,000 years ago - way before the Clovis period. The picture emerging here is very complex. It seems different groups coming from numerous places inhabited the continent and some seem to have come at a much earlier period than the Clovis theory allows.
My response is:
In this set of materials, the reading passage supports Clovis-first theory stating that first people migrated to American continent through a bridge called Beringia while the listening passage in contrast mentions some facts some which weaken that theory.
In the reading passage, the author states that first immigrants settled America by crossing a land bridge Beringia since that time the level of the sea was low due to the global glaciation but they could not move southward because the terrain which is now Canada was covered with ice sheets. Afterwards when the sea level declined humans populated in the southward. But the migration from Asia to America stopped at the end of the Ice Age.
In the listening passage, the professor states three evidences that weaken Clovis theory. Firstly, researchers have found many places in American territory which are much older than those of Clovis. Secondly, the oldest people found by Clovis mostly resemble Pacific island population which contradicts Clowis’s theory.
Last but not least, DNA results indicate that Siberian people inhabited American continent about forty thousand years ago and this date is not correlated with Clowis’s one.
TOEFL listening discussions: A conversation between a research professor and a student