I'm a believer in the William Golding (Lord of the Flies) view of humanity - that the baseline character of humans is quite different than what you see in modern humanity and that what makes us who we are comes from social controls and not instinct.
IOW, human character is malleable and constantly changing. It's not surprising that something as significant as the Internet (not computers on their own) is changing us again.
I think our human nature is more a function of scarcity than anything else. If you look at Colin Turnbull's work comparing the Pygmy tribes to the Ik tribes, it's pretty evident that under harsh conditions people are more ruthless and selfish then under conditions of relative plenty.
I like to also compare the Old Testament from Deutoronomy onward and Gilgamesh. In Gilgamesh, which is a much older book, the world is vast, lonely and mysterious and man's primary struggle is with the forces of nature. In the Old Testament, the world is crowded and the the story line is dominated by near constant never-ending warfare.
My question in response is, "is that qualitative difference also qualitative?" I'm starting to think I agree, as long as you extend "scarcity" and "harshness" beyond the purely economic.
Otherwise how do you explain what appears to be the majority of modern jihadists coming from at least the upper 1/2 of society, if not solidly middle class or above, e.g. the 9/11 hijackers?
Of course, your thesis doesn't have to explain all examples of being "rutheless".
As for your last point, hmmm. Is that in part a function of viewpoint, of e.g. the author(s) and audience(s)?
ADDED: other counterexamples: The Japanese in WWII, the actions of some high caste Indians towards lower caste ones. (As a matter of fact, in India in the last few decades, while incomes have gone up, calories and quality of them has gone down for those lower on the socioeconomic scale...).
And with the new technologies we risk letting out our brutal unconscious tendencies again. Violence in form of cyberbullying. Selfishness in form of narcissistic social networks. And more problematic, having groups with extremist anti-social attitudes reach critical mass.
I agree about letting our brutal tendencies out.
I don't agree with the redefinition of violence from physical harm to include cyberbullying. Bullying is correlated with acts of violence, but violence and bullying are different things.
I think our in-group out-group behavior and all the brutal tendencies stem from our very evolution. Macques do the same thing ( http://psycnet.apa.org/psycinfo/2011-01598-001/ ).
That being said I also don't think any group has an extremist anti-social attitude. It seems like an paradox, how do people who are extremely anti-social form a group, wouldn't they just be bunch of isolated loners ? I think are simply extremist towards people they see as the "other" or outside their group.
IOW, human character is malleable and constantly changing. It's not surprising that something as significant as the Internet (not computers on their own) is changing us again.