Today marks Equal Pay Day, when based non the disparity in pay between men and women, the latter are effectively working from free from now until the end of the year. It's an emotional topic, but what does science have to say about the whole issue?

A common argument for why the gender pay gap exists is that women tend to work in lower-paid occupations. But new in-depth research has found even when contributions to their employers are the same, women are still paid only 84 cents for every $1 men receive.

Why? Well, it's sexism, they say.

Five years ago, Silicon Valley was rocked by a wave of “brogrammer” bad behavior, when overfunded, highly entitled, mostly white and male startup founders did things that were juvenile, out of line and just plain stupid. Most of these activities – such as putting pornography into PowerPoint slides – revolved around the explicit or implied devaluation and harassment of women and the assumption that heterosexual men’s privilege could or should define the workplace. The recent “memo” scandal out of Google shows how far we have yet to go.