Pinker devotes an entire chapter of the book to gender, and the first half of that chapter to workplace equality. His thesis here is that a lack of 50-50 gender equality in a given profession isn't necessarily indicative of discrimination or unfairness, unless you believe in the blank slate. That is, unless you discount the possibility that women, on average, are interested in different things than are men. He goes on to present a vast amount of evidence that such differences in preference do exist, regardless of cultural conditioning.
This isn't to say that discrimination is non-existent. Many of us have seen (or heard) enough to know that it's alive and well. The point is that we shouldn't arbitrarily strive for perfect 50-50 equality. There will always be fields in which men and women outnumber each other by large margins, and that's okay. The best we can do is to try and stamp out discrimination wherever possible.
If you look globally, there are countries where that isn’t the image, and in fact, their numbers are dramatically better. I was recently speaking with some of our Oracle engineers from China and they pretty much have a fifty-fifty split of men and women. And they think it’s sort of odd that we don’t.
Also, from a scientific perspective, this is a disastrously imperfect experiment. You cannot rule out the effect of the genes unless you control for that. Looking at a group of people who are physically different AND culturally different , then arbitrarily concluding that any differences are the result of cultures is about as unscientific as it gets.
As to the second point, humans are not very genetically diverse. Of course there are enough differences that we can sometimes conclude that a particular person's genes come from an ethnic group, but it's not as nearly as varied as even other primates. Basically, we hit a genetic bottleneck sometime in the past 100,000 years. So it's far more likely to be a result of culture than genes.
2) who's even suggesting that we need a 50/50 gender balance? Where are you getting this straw man from? All McClure has asserted is that there should be more women in tech, and given our 9:1 M:F ratio... there's a lot of room to move before we even start to discuss whether 50/50 is an appropriate ratio.
Also, I'm not attempting to refute Dave McClure or anyone specific. I never claimed that he claimed we should strive for 50-50 equality, so it's unfair for you to accuse me of a straw man. I'm just making reference to an argument that happened to affect my personal view on the matter. This topic has come up again and again on HN and in tech-related blogs, and I think it's a very common viewpoint that any deviation from a 50-50 distribution is attributable to discrimination.
Regardless, I agree with you that that current ratio is overly-extreme, and that we can do better.
I recommend against holding up pop-science cults of personality if you would like people to take you seriously.
See what I did there? Evidence or bust.