There's an interesting lecture from Albert Bartlett [] on the same subject, but he uses the value of 70 to calculate the years to double.
[] http://www.youtube.com/watch?v=F-QA2rkpBSY
Don't you think it is contradictory to support both views that racism and sexism "help us make better decisions" AND that there is an "expressed desire of changing" that? Why would you want to change something if you think it helps you make better decisions?
So my conclusion is that the parent comment is only looking for excuses for being racist, namely that it allegedly helps and that people are generally racist. It doesn't and we don't have to be.
"Courageously" admitting something doesn't make it OK, simply based on the speculative assertion that a lot of people do the same.
We may be living in a biased society, but admitting this doesn't make it excusable.
The problem is not in the admission process, but (amongst other things) in each individual's perception about it.
A mostly male club with only 4% women will naturally attract more male population, making the group even more unbalanced over time.