If you were to unfurl the tattered skein of human rights, and then trace the many scarlet threads of human wrongs interwoven therein, following them back through the knots and coils of history, eventually you would reach the crucial moment when the fratricide Cain found himself looming over his victim Abel. Considerable speculation has naturally been devoted to the particulars of this Ur-murder, though the basic fact pattern provided by the Hebrew Bible is well enough known: violently jealous and “very wroth”, Cain “rose up against Abel his brother, and slew him”. A great many details are admittedly missing here,…