Evolving ourselves out of existence

Still reading quite a bit. Just finished “Lies My Teacher Told Me” (it was OK – not sure I reccomend it though) and then finally started and finished “The Lean Startup” which if you have tough projects to get done is a must read IMHO.
Now I am on to “Hamlet’s BlackBerry” which describes the problem and some solutions to being over connected and/or over stimulated by information. I’m about 1/3rd into it and so far so good. One point the author brings up its the research that shows we get a small “squirt” of dopamine when we get a new text,  email or status update. This is seen by neuro scientists as an evolutionary artifact from when we needed to pay more careful attention to our surroundings, both to watch for something that might be trying to easy is or for something we might be able to eat.
This for me wondering. What happens in an evolutionary cycle or two when that response has been weeded out of the gene pool and we are no longer as aware of what’s found on around us after too many tweets, pings and beeps over too many generations…and then for whatever reason we need it again?