I like to think of this as a critical learning cycle. It is a time to teach children the consequences of their behavior. In addition, it allows them to learn during heightened emotional states. This is not the first of these cycles.
Think of what would happen if this cycle never occured before a person reached adulthood. For example, if you were to become angered by someone for the first time at age 20, you might hit them. If the person hit happened to be the wrong person, the consequences to the hitter could be multiple times worse, even fatal.
It is not uncommon for a 2 year old to bite someone for the first time. First, they probably have no idea biting another person hurts this person. Second, they have no idea there are consequences to bad behavior directed at others. Third, they may be experiencing anger for the first time and have no idea of what to do with it.
I don't think everyone will agree, but I feel the best thing you can do for a child the first time they bite is bite them right back and make sure it hurts. Depending on the child, you may only have one opportunity to make this lesson effective. You may also only have a matter of 2 to 3 seconds to respond as well. Any longer and it will not work. I like to think of this as possibly saving the child a much worse experience later in life.
