Mesquite Seed Pods

This time of year around here the Mesquite trees produce a prodigious amount of seed pods.  Each of six or so species produce different looking pods, but a given tree can deposit several zillion seeds making a mess of the patio or pool.  Why do they need that many?  I'm told some people grind the pods into a non-gluten flour.  I just grind them into an abstract photograph...