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1 .<-NARRATOR:-> Now listen to part of a lecture in a biology class.
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1 .<-MALE PROFESSOR:-> Prairie dogs' re small animals you're likely to find on wide, relatively flat, grassy areas of land in North America.
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2 .They tend to live together in large numbers. Now,
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3 .generally these animals don't come into contact with human beings, but every now and then they do. So
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4 .let's assume that some prairie dogs happen to live in an area where human beings frequently come and go.
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5 .Now, the first time the animals would see a human being,
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6 .they'd instinctively react by making a sharp barking sound-
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7 .like a dog- ...
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8 .and jumping up and down-
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9 .essentially warning or alerting other prairie dogs that are nearby of
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10 .this potential threat.
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11 .Exactly the same way that they'd react if they came upon or were threatened by a snake or a hawk,
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12 .an animal that preys on them.
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13 .Their instinctive reaction would be one of fear.
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14 .They'd keep an eye on the human beings
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15 .until these "scary", possibly threatening, individuals are gone. And
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16 .they're likely to react this way every time they see a human being.
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17 .However, if people pass through the area day after day
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18 .without threatening them or trying to harm them,
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19 .well, it turns out that the prairie dogs will gradually stop barking and jumping up and down when they see a human being passing through the area.
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20 .At some point they'd stop reacting to humans as though they were a threat.
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