Betty Davis (Miles Davis’s ex-wife) was a true funk pioneer.   She released some terrific but unheralded albums during the early-to-mid 1970s.  Seattle’s terrific Light in the Attic record label (who also recently re-released Sixto Rodriguez’s classic early albums) re-released a lot of her stuff a few years back.  Much of it is still available, but Davis’s “Nasty Gal” album no longer appears to be in print.  In any case, this is well-worth tracking down.