Are we all in fact spir­i­tu­al? Is this term sim­ply a vague, redun­dant descrip­tion?

A read­ing list for this top­ic is online at http://thormay.net/unwiseideas/DiscussionTopics/SpiritualPeople.htm  (Sug­ges­tions for addi­tions are wel­come)

Is love an evo­lu­tion­ary instinct? I.e., is it an innate, uncon­scious impulse that has been encod­ed into our genes over mil­lions of years as a mech­a­nism to ensure the sur­vival of (the whole or indi­vid­u­al mem­bers of) the species? Or is there more to it? Is there anoth­er way to explain it? Do all ani­mals expe­ri­ence love?