I would personally wonder how they knew it was a female skull. Brow ridges tend to be more common in males, although they're definitely not an infallible sign of gender. Anyway, what Dwight said is quite true: people vary. People of some racial groups tend to have larger brow ridges than others, some individuals within groups have larger brow ridges than the others. . . And in case anyone was curious: No, that doesn't mean that some racial groups are 'more primitive' than others. People are just different.
Cruise over to
http://catalog.universal-net.com/pageserver.php3?
clid=bc&cat=1&sku=BC-31
That's a page from a WWW catalog of skull replicas, showing a replica of an Australian aborigine skull, with relatively large brow ridges. (I'd rather not get into the multiregional vs. uniregional hypotheses of modern human origins, or the differing ideas about Neandertals. . . nor am I saying that Australian aborigines are 'less advanced' or 'less human' than anyone else; hell, no! Just trying to make the point that modern humans are a variable species.)