托福口语 Task 4

Today we're going to talk about a fascinating concept in animal behavior called 'biological altruism' — actions that seem to benefit others at a cost to the individual. But how can such behavior evolve? The key is that altruism often targets close relatives, thereby helping to pass on shared genes. Let me give you two examples. First, consider ground squirrels. When a predator approaches, a squirrel may give a loud alarm call, warning others to hide. However, this call also draws the predator's attention to the caller, increasing its risk of being attacked. But because the squirrels in the group are often siblings or other kin, the warning helps ensure that many of the caller's own genes survive in those relatives. Second, think about honeybees. Worker bees are sterile and spend their whole lives caring for the queen and her offspring. They don't reproduce themselves, but the queen's daughters — the new workers and future queens — share a high proportion of their genes with the workers. By helping the queen reproduce, workers indirectly pass on their own genes through their sisters. So, in both cases, what looks like selfless sacrifice actually serves a genetic purpose.