Maybe Warriors were the result of a genetic experiment. At some point in the distant past people badly needed super-power fighters and some Dr. Frankenstein had the bright idea to steal a few cat-genes and implant them in male human embryos. They were never meant to procreate, but they did anyway. By now, the (recessive) genes are in virtually every bloodline. As we've not seen a female warrior yet, I'm assuming that women can pass the gene down the line for a couple of generations without anyone noticing until some day, in some family, a male baby is super-hungry and super-strong.