英語(yǔ)聽力：猛瑪象進(jìn)城記—2

To find the answers, we need to rewind history around 14,000 years to a time when the first people set foot in North America. The continent was about to undergo a profound change, a change these new arrivals may have played a part in.

Throughout the ice age, North America was home to a variety of giant creatures. But in little more than a thousand years of the first humans’ arriving, almost two thirds of the largest animals were extinct.

What role did people play in this mass extinction? To learn about their lives, you have to look at the clues they left behind.

Archaeological finds tell us that the first people in North America had an advanced Stone Age technology. They were master of flintknappers meticulously chipping and sharpening pieces of flint to make spears and cutting tools. From the examples they left behind, it's obvious they were well equipped to hunt.

And we know from spear points found alongside mammoth remains that these hunters tackled even the biggest beasts on the continent. Mammoths would have been a prized source of protein, providing enough meat to feed their families for weeks. The hunters probably worked in pairs or small groups. Any mammoth straying from its own herd would have been singled out.