Surgical staples with deformation zones of non-uniform cross section

A staple having a backspan and two legs, each of said legs having a tip and an elongated deformation zone, each of said deformation zones being more susceptible to bending than other regions of staple legs adjacent to each of said deformation zones when said tips of such staple legs are forced toward each other, the legs having a cross section area outside the deformation zones, each of said elongated deformation zones including an intermediate region that is tapered and that varies in cross sectional area within said deformation zone, along the length thereof, such that said cross sectional area is different at a location of said region closest to said backspan than it is at a location of said region closest to said tip of said legs, the cross section within said deformation zone smoothly varying at each end thereof until matching the cross section of said legs outside the deformation zone.