托福口语 Task 4

Today, we're going to talk about a fascinating phenomenon in animal behavior known as 'reciprocal altruism.' This is when animals help others who are not their direct relatives, with the expectation that the favor will be returned in the future. This isn't just random kindness; it's a strategic survival mechanism. Let me give you two examples. First, consider vampire bats. In Central and South America, a bat that has had a successful blood meal will often regurgitate some blood to feed a hungry bat that didn't find food. The key is that this isn't one-way. The bat that received help is much more likely to return the favor when the other bat is in need. This reciprocal relationship increases the chances of survival for both individuals. Second, think about the cleaner wrasse, a small fish that cleans parasites off larger fish. Sometimes, the cleaner wrasse will gently nibble the inside of the larger fish's mouth, which is a very vulnerable area. The larger fish could easily eat the wrasse, but it doesn't. Why? Because it benefits from the cleaning service. And the wrasse benefits too, because it gets a meal. This mutual trust and repeated interaction form a reciprocal system. So, in both cases, helping another animal, even at a potential cost, is beneficial in the long run if the favor is likely to be returned.