Ask A Scientist

What does it mean when a dog wags its tail?

Asked by: Bethany Cobb
School: Maine Endwell Middle School
Grade: 7

Hobbies/Interests: Animals, basketball

Answer from Debbie Dittrich

Research Support Specialist

Research area: 
Teardown analysis of electronic packages
Docent at the Binghamton Zoo, nature photography, gardening 

You have probably been greeted at some time by a dog wagging its tail.  You probably understood that this dog was glad to see you.  The dog was wagging its tail because it was happy, but also because it wanted to communicate this feeling to you.  But why did the dog want you to know how it was feeling?

DNA evidence suggests that dogs are descended from gray wolves, probably a result of our ancestors' interactions with wolves perhaps 15,000 years ago.  Gray wolves are social animals, which means that they like being with other wolves. Typically, they live in packs of 5-11 individuals, consisting of a mated pair and their offspring.  You are also a social animal, so it may help to think about your own family. Communicating with your family members is important to ensure that everyone gets along.  Supposes that your family had no way to communicate.  Conflicts might sometimes result in physical combat.  Now imagine your opponent to be armed with a powerful jaw and sharp teeth. You can understand that resolving conflicts without force would be preferable!

A pack of wolves must work together to hunt, raise their young, plus defend a territory and and the ability to communicate is essential for achieving these means.  Humans rely a great deal on language to communicate, but tone of voice, facial expressions, even body posture help to convey information.  Wolves too use various vocalizations (barks, yips, howls, etc.) and body language when relating to each other.  Body scents (such as urine) also play an important role.  A wolf facing the situation above may be able to avert a fight by using its body to show submissiveness (cowering to the ground with tail between the legs).  You have seen a dog do this when it meets an unfamiliar dog.  In fact, dogs and wolves are very similar in this respect.  A playful wolf will bow its front end down, with its rump up and tail wagging, just like a dog!

There is an endless variety of methods animals use to pass information along.  Bees dance to help other bees find food sources.  Some lizards change color to reflect their mood. Elephants emit sounds so low in frequency that we can't even hear them because such sounds travel great distances.  Pay close attention to the animals around you and you may learn what they are trying to tell you.

Last Updated: 3/1/17