การฟัง TOEFL

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Listen to part of a lecture in a biology class. The professor is discussing animal communication. Professor: Today, we're going to talk about how animals communicate, specifically focusing on the concept of 'honest signaling.' In evolutionary biology, an honest signal is a signal that is reliable and cannot be easily faked. For example, the peacock's tail is a classic honest signal. It's costly to grow and maintain, so only healthy males can produce a large, vibrant tail. This cost ensures that the signal is honest—it truly indicates the male's genetic quality. Another example is the warning calls of some birds. When a bird gives an alarm call, it might attract the attention of a predator, which puts the caller at risk. So, the call must be honest because the bird pays a cost if it lies. However, researchers have found exceptions. Some species use 'tactical deception,' where signals are used to mislead others. For instance, a certain type of monkey gives a false alarm call to scare others away from food, allowing the caller to sneak in. So, while honest signals dominate, deception can evolve under specific conditions. Any questions? Now, let's consider how this applies to human communication...