Most Astronaughts have military training, so they were taught to fight

Also the cave men I am betting were not highly nurushed, think about it people have been getting bigger and bigger. So

They have have a club, but would they think to throw rocks and sand?

and the whole bar fight is a joke, cave men have no tolerance for alcohol and anyone who straps there *** to Giant missle (built by the lowest bidder) can toss a few back.