Older and wiser has a special meaning when it comes to elephants, as we discuss in this Moment of Science. Today's show proves once again that older and wiser go hand-in-hand. Take elephants for example. Did you know that female elephants decide whether another elephant is a friend or a stranger by listening to its call?

Identifying elephant calls correctly is important because encounters with strangers often result in disputes. When elephants hear a strange elephant calling, they get defensive and cluster around their calves to protect them. Anyway, a study suggests that the older the matriarch of an elephant family, the better able she is to pinpoint whether the call she's hearing is from a friend or foe.

What's more, the same study noted that groups of elephants that travel with a more experienced matriarch also produce more calves. Scientists think it's because they might be calmer. Because the matriarch does such a good job identifying danger, her family isn't as stressed and doesn't waste as much time clustering as the family of a matriarch who sometimes issues false alarms.

The problem is that when hunters go after the biggest specimens, they often kill the oldest members of the group, leaving the group without the kind of social knowledge and leadership that help them succeed. So scientists are wondering whether this explains low birthrates not only in elephants, but in other species, like the sperm whale, where the largest and therefore oldest members of the group are also hunted.