托福口语 Task 4

Today we're going to talk about a fascinating behavior in the animal kingdom: altruism, or when an animal acts in a way that benefits another individual at a cost to itself. Now, you might wonder why such behavior would evolve, since it seems to reduce the animal's own chances of survival. The key is that altruism can still be beneficial if it helps relatives who share the same genes. This is called kin selection. Let me give you two examples. First, consider ground squirrels. When a predator like a hawk approaches, a squirrel will often give a loud alarm call to warn others, even though this call draws the predator's attention to the squirrel itself, increasing its risk of being caught. But the squirrel's relatives—its siblings, offspring, and cousins—are nearby in the same colony, and they all benefit from the warning and can escape. So by risking its own life, the squirrel ensures that many of its shared genes survive through its relatives. Second, think about honeybees. Worker bees are sterile females, so they don't reproduce themselves. Instead, they spend their lives foraging for nectar and defending the hive, sometimes stinging intruders, which causes the bee to die. But the queen bee is their mother, and the other workers are their sisters. By protecting the hive, they ensure that the queen can continue to produce more siblings, passing on many of the same genes that the workers carry. So in both cases, the self-sacrificing behavior actually increases the survival of the animal's own genetic material through close relatives.