First of all I'm 22 and not living US so I can only talk about growing up in Germany but there is one thing I learned growing up in Germany: Fist fighting is not a solution. I never used my fists in my entire live (!!) to beat someone cause I don't think it could change a situation into a better situation.
I think we can all talk. Saying that it is what works because of our "animal nature" it's plane wrong. We would never live in this democratic world if everyone would use their fists to make things right.
Also it is really URGENT to tell kids that this is not a solution cause this will never be a solution while getting older and sometime a job. At work it will not help you to beat someone if he/she is bullying around with you. You will lost your job if you do so.
So please stop telling your kids a solution which only COULD (I don't think it works though) work in school. Worst thing what can happen is that your kids will try to solve every problem with a solution father told him/her.
Last but not least I know very well how hard school can be for kids but developing a good personality needs downs and ups. We are all "nerds" and I think we know hard times really well.
Thank you for listening.