托福口语 Task 4

Today we're going to talk about a fascinating behavior in the animal kingdom: altruism, which is when an animal acts in a way that benefits another individual at a cost to itself. This seems to contradict the idea of survival of the fittest, but there are evolutionary explanations. One key mechanism is kin selection. The idea is that animals are more likely to help close relatives because they share genes. For example, in a squirrel colony, when a predator approaches, a squirrel will give an alarm call to warn others, even though this draws the predator's attention to itself. The squirrel does this because its siblings and offspring, who share many of its genes, are nearby and can escape. The cost to the squirrel is balanced by the increased survival of its relatives. Another example is seen in certain birds called scrub jays. Older offspring from previous broods often stay and help their parents raise new chicks. They feed and protect the younger birds, which are their siblings. Although they don't have their own offspring, they increase the chances of their parents' genes, including their own, being passed on. So, even though the helper doesn't reproduce directly, its genes are still represented in the next generation through its siblings.