On Desert Sons, Nick Long (Lonely Horse) and Travis Hild (Heavy Foot) get in rhythmic fisticuffs with their axes and skins. Playing each other as much as they play their own instruments, the duo has been poised to drag S.A. pop music into the 21st century for several years. The loogey-fuzz of Long’s guitar and the Keith Moon-meets-Cherokee-drum-circle powder keg of Hild’s foot and right hand could grind maize into flour, or mota into keef. Lonely Horse would probably have a steady growing catalog of panties and unmentionables if they used their conjuring for typical rock ’n’ roll spoils — the sex and the drugs — but Long’s lyrics just aren’t vacuous enough. As Chuck Berry, Lightnin’ Hopkins and Jagger/Richards could make the most shallow, frivolous topics seem like aural molly so, too, can Long make the genocide of the planet, its native peoples and the resulting helpless depression equal parts inflaming and humbling. If they get any bigger, surely, much of their sincere shamanism will be lost in the shutter of the burgeoning crowds’ iPhone clicks, but it can’t capture their souls.