Unit 3 A healthy life reading课时作业

Ⅰ. 阅读理解

Under the cold clear water of Lake Huron，researchers have found a five­and­a­half­foot­long piece of wood that is 8,900 years old. The wood，which is tapered(使成锥形) on one side in a way that looks deliberate，may provide important clues to a mysterious period in North American prehistory.

"This was the stage when humans gradually shifted from hunting large animals to fishing，gathering and agriculture，" said anthropologist John O'Shea. "But because most of the places in this area that prehistoric people lived in are now under water，we don't have good evidence of this important shift itself. We just have clues from before and after the change. "

With support from the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA)，O'Shea and his colleague Guy Meadows began exploring the area several years ago. In 2009 they reported finding a series of stone features that they believe were "drive lanes" used by ancient Indian hunters.

Since that discovery，O'Shea and Meadows have worked on identifying human campsites，which are typically located away from hunting areas. On their 25­foot boat，the researchers first spotted the ancient wood object using a small piece of equipment with a camera. Then a team of divers-including O'Shea-went down about 100 feet to get it.

The wood's age has now been fixed by means of carbon dating. It is currently undergoing more detailed analyses to determine whether there has been human modification，which visual examination suggests. "The first thing you notice is that it appears to have been shaped with a rounded base and a pointed tip，" O'Shea said. "It must have been created. It looks like it might have been used as a tent pole or a pole to hang meat. "

In addition to the wood，the researchers have collected many other samples from the bottom of the lake. O'Shea and his colleagues will need to wait for calmer weather before they can resume their search for evidence of human life under the great lake.

【语篇解读】　考古学家们的新发现有望印证远古人类从游猎文明到农耕文明