I want to guess that the "traditional roles" stance stems from what most anthropologists believe of the prehistoric world; human males were stronger and "in charge". This, traditional male-female structure, is seen in some areas of the higher animal species but definitely not all. Human males being dominant during all phases of Darwins evolution cannot be proven, so the link from them to us is speculation. What seems more probable, as an act of instinct, in the modern world is maintaining a sort of status quo by whatever means necessary, which is also visible in many animal species. Hence, its argued, traditional roles are natural, even Darwin would agree. I think this feeling is most likely human consciousness making a rationalization based on subconcious/instinctive drive to hold and control power and influence, also known as maintaining the status quo. The instinctive drive to consolidate and hold power is evident in most social animals. From lions to ants, animals will fight and die to maintain control of, for the most part, a genetic lineage and/or territory.(ie natural selection). But, what about social structure? Different species have taken different paths in establishing structure, again, probably by means of natural selection. No one can say where social structure began, but regardless it's a natural component of many animals. But what happens when the ability to recognize and analyze these structures has been gained? Does this give us the potential to break male-female roles or does our historically percieved instinctive social structure bind us? So this we know, the western world still is and has always been a man's world. We know , most of us anyway, that men and women are intellectual equals. And the debate is whether we could/should break away from "traditonal" gender roles and whether Darwin's ideas support this one way or the other, right? I say this, the cornerstone of Darwins work is evolution, naturally doing what makes the individual/species stronger, not what chains one to the past. Lets evolve.