I'd say frequent rather than possible. Maybe not often on the big scale but I reckon it's just a basic and natural part of all of us; an unthinking reaction to help out. I think so anyway.
I do reckon what happens though is that we live in such pressured environments, especially in cities, that we do get self-centred and protective... and become, rightly in cases, suspicious and weary of helping out. You have to be aware of that and chill out a touch.
But I do honestly think that in a healthy environment, where we are less pressured and chilled out, then we do revert to our natural way of being. It might sound like a cliche but happy, relaxed people are basically decent and good hearted too.