In reply to pork pie girl:
Interesting discussion. I am trying to avoid doing work so...
Your opening post is something I have thought about a fair bit and have noticed the same thing as you.
I think that there are a series of things going on (as always this not based on science just my opinion!):
Initially at a beginner level I think it is fair to say that most guys are able to do more pull ups than women and have more muscle mass in the back, lats, biceps and shoulders etc.. Therefore it is fairly obvious that most guys will tend to be able to climb steeper ground more easily than a woman. Obviously their technique will be bad and they will be using lots of unnecessary energy but the point remains that they will be able to get up a steeper more powerful climb than your average beginner woman. I understand that there are exceptions to this but in general I reckon it holds true.
As with everything being better at one thing tends to mean that you will do more of that thing generally because most people like to do well at things and not look or feel bad at something that others seem to find easy. So this then means that lots of guys get sucked into climbing steep ground with big holds and lots of women then dont want to try steep ground because they prefer vertical or technical climbing that they are good at. The more this continues the better each person/group gets at the thing they do and the bigger the disparity grows. Obviously I am generalising a lot here but I still reckon if you look around when climbing inside at people who are beginner/intermediate level (whatever that means) it does mostly hold true.
There is also a group effect type thing. If you look around a wall and see that the steep stuff is populated by guys with their tops off, sweating, grunting and monkeying their way around and that the vertical/slabby has lost more women then you as a beginner/intermediate climber could be forgiven for assuming that guys climb steep stuff and women are better on the vert!
In my opinion as the standard increases this starts not to hold true as much and the differences start to even out quite a bit. Yes in general I still think that your average guy who redpoints sport 8a is likely to have a greater liking for steep ground and thuggery than your average female that redpoints 8a but the difference is much less profound and it is likely that the female in question could still climb really well through roofs and steep ground. Also as the climbs get harder raw power begins to be less and less important, rather steely fingers, good power endurance and good technique are much more important. To be honest being able to do a one armer and 1-4-7 has never helped me very much sport climbing. Personally if I lose my feet on a climb it is normally all over and I have certainly never needed to crack out a one armer! That is not say that it isn't good to have a bit more power in the tank on some moves just that I think it rarely makes much difference and that from someone who likes campussing and generally maintains an ability to crack out a one armer!
Personally I think that there are obvious phsyiological differences between men and women's muscle mass and ability to generate power, however I reckon that most of the difference comes down to not training that particular thing.
For example I personally am not the greatest on the vert (in fact I suck), the answer is relatively simple as to why. I don't do much of it, I generally avoid it and therefore don't climb very well on it. However once a year or so I make myself do a thin vertical wall climb that is somewhere near my top grade, initially I can hardly move and hate it but by the end of the process (if I don't spit the dummy) I move much better and have relearnt how to de-weight the fingers, keep the hips in and put more trust in my feet etc..
Dave