What The Heck Is Up With Peter?

So, I'm watching Fringe online today (I was out boozing last Friday and didn't get to see it on TV.) and here we have Peter Bishop being all Terminator, exterminating shape shifters without a hint of remorse.  Weaponized?  He sure seemed like a heartless android, single-minded in his efforts to get answers by any means necessary.  Granted, he was actually doing a good thing by taking out these undercover spies but so callously?  Perhaps he's reverting back to pre-Fringe Team Peter, the crook/con man/mercenary bastard.  Still, such a shockingly abrupt personality change...intriguing!

Speaking of abrupt changes, Astrid Farnsworth actually getting to use her technical skills and training?  Yay! for Astrid!!  More of this, please.

I know this is a fictional show, but I started thinking about the possibility that maybe there could actually have been societies that existed before our own, but that faced extinction.  I don't know why that should be so far fetched.  Then I think about the very exact set of circumstances (understatement) that led to our existence, and I'm not so sure that it would've been possible, not a civilization as advanced as ours.  Interesting plot point, though, and I can't wait to see where they are going with it.