I am not suggesting that there is competition between males and females - both are in competition with the rest of their world, especially with their prey and others seeking the same prey. If one posits that the tusk was sufficiently advantageous in helping males feed that it was selected for, that seems to imply a corresponding disadvantage for tuskless females in their competition with the rest of the world. If the female ancestors could feed just as well as the males, then what was the source of the selective pressure on males alone? Perhaps the males' sexual competition between themselves demands more food or leaves less time to find it?