Nghe TOEFL

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Narrator: Listen to part of a lecture in a biology class. Professor: So we've been discussing animal communication, and today I want to focus on a fascinating example: the waggle dance of honeybees. When a foraging bee returns to the hive after finding a good nectar source, it performs a series of movements on the vertical surface of the honeycomb. The dance consists of a figure-eight pattern. The straight part of the dance, called the waggle run, is the key. The angle of the waggle run relative to vertical indicates the direction of the food source in relation to the sun. For example, if the waggle run is straight up, the food is directly toward the sun. If it's at a 45-degree angle to the left of vertical, the food is 45 degrees to the left of the sun. The duration of the waggle run encodes distance. Longer waggles mean farther away. Interestingly, bees can adjust this dance based on the quality of the food source—richer nectar results in more vigorous dancing. This discovery, first made by Karl von Frisch, was revolutionary, but it wasn't immediately accepted by all scientists. Some doubted that bees could convey such abstract information. However, subsequent experiments confirmed that other bees indeed follow the dance and then fly directly to the location, even when the food source is miles away.