I don't think theres one simple conclusion to this ongoing general question of pre-history vs modernity but I remember coming across the infanticide and geriatricide rates in pre-agricultural societies (not that they were / are all the same) at some point and having it complicate my thinking pretty drastically.
I believe it was in here, its a quick interesting read in any case.
http://public.gettysburg.edu/~dperry/Class%20Readings%20Scan...