It's also been my perspective that what's been on the increase is information sharing (duh) and our fascination with "train wrecks" whether they be actual disasters or human misanthropy. There is more violence now because there are more of us in the world... but, as Ian pointed out, the rate is the same.
I make the same contention (anectdotally as I have no statistics) that the net is no more dangerous, per capita, than any other venue for meeting people. Just more of us here to prey on and therefore more predators... but no more than your local pick-up bar... and perhaps a better opportunity to weed out the wheat from the chaff because you don't have to make snap judgements.
btw... Thorne... most life expectancy figures include infant and childhood mortality dragging the numbers down for times past. I would suggest that those who made it to adulthood (13 y.o.?) lived a relatively long life.