FPTP tends to enhance discrimination against women and minorities, because each riding only elects one candidate, and so nominating a white male is not a bad choice.  Multi-member districts under systems such as STV force parties to diversify the candidates they nominate so that between them they can appeal to as many voters as possible (So some old, some young, some male, some female, some white, some Chinese, etc.).  Craig Henschel's OCA Submission (Attached Below) has details on page three.

Here is some good material on STV and women:

1.  Shoni Field's (A former Citizens' Assembly member) article on women's representation and STV (Attached Below).
2.  A graph on women's representation and government system (Attached Below).
3.  David Huntley's Summary of Lijphart's book 'Patterns of Democracy' (attached Below).  Perhaps the most relevant part is excerpted below:

Then, Lijphart examines several measures of the quality of democracy and democratic representation. Consensus democracies [Which usually use more representative voting systems] come out better for the percentage of women in parliament, the percentage of women in cabinet, family policy (parent leave on childbirth,  daycare, retirement system flexibility), rich-poor ratio, distribution of economic power, voter turnout, the satisfaction of voters with their democracy, distance between government policy and the wishes of voters, and two overall measures of democratic quality. These correlations are all significant at the 10% level, some at 5% and some at 1%.