Bears tend to charge loud noises like air horns, rifle shots and aggressive yelling.  They respond much more calmly to talking, jingling and any (non-agressive) noise that alerts them that you are present. That said, the quiet of a lone runner certainly sets them up for a surprise, which we know they don't like either.  If you do some research, you will find that mace is actually extremely effective and not as you imply. I think individual runners should carry it as a precaution. If we are going to pay thousands of dollars to chase and wound a bear AFTER someone gets hurt/killed, then why not rather spend a few hundred on mace BEFORE someone is hurt/killed? That poor boy and his poor family.