Joshua Tucker: The following is a guest post from University of North Carolina-Chapel Hill political scientist Andrew Reynolds.

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Today, Zakhele Mbhele, a member of the opposition Democratic Alliance, was sworn in to the South African National Assembly. He is the 203rd openly gay member of parliament worldwide since Coos Huijsen became the first, in the Netherlands, in 1976. The symbolism is made more vivid by the fact that Mbhele is the first openly gay black African to be elected on a continent where laws designed to invalidate gay people have destroyed countless lives.

There is an unsettling polarity in the state of gay rights around the world today. The march toward gay rights in much of the developed world has sped up to a dizzying pace. More and more countries have introduced same-sex marriage and other equality laws. Today, well over 700 million people live in places where gay marriage is legal; over 120 million of those are in the United States. In the United States, progress on gay rights has evolved more quickly than any other social transformation of the past century: much faster than changing views on race relations and civil rights. In 1996, support for gay marriage was at 27 percent; in 2014 it was 59 percent. In early 2014, 72 percent of Americans saw the recognition of same-sex marriage as inevitable.

But gay people in much of the world still face extreme violence, social ostracism and legal repression. In more than 80 countries, homosexuality remains illegal, and in five of those, conviction can bring the death penalty. Brunei introduced a law this month in which conviction for same-sex acts would bring death by stoning. Africa in particular remains a very dangerous place to be gay. The presidents of both Nigeria and Uganda signed into law extreme anti-gay legislation this year. High-profile gay rights advocates have been murdered in Cameroon, Kenya, Sierra Leone and Uganda. South Africa may have one of the most progressive constitutions in the world when it comes to gay rights, but the distance between legal niceties and the reality of daily life can be a chasm. Many gay, lesbian and transgender South Africans are forced to live secretive and fearful lives, and the “corrective rape” of lesbians is commonplace. Into this maelstrom steps Mbhele – a 29-year-old LGBT activist and former spokesperson for the Democratic Alliance leader, Helen Zille.

Can the election of a single person matter? It is no shock to learn that knowing someone who is gay affects the way people think about homosexuality and gay rights. Indeed, the number of Americans who support same-sex marriage in the U.S. has tracked closely the number of people who say they know a gay person. As more and more people say they have a family member, close friend or co-worker who is gay, support for marriage equality and other gay rights increases among those people. Likewise, there is powerful evidence to show that openly gay members of parliament, state legislators, mayors and councilors have a dramatic impact on the progress of gay rights in their countries, states and towns. Simply having a single LGBT legislator in parliament is correlated with national laws that are up to 20 percent more inclusive of gay rights. The relationship is statistically significant even when one controls for other plausible explanations such as government ideology, level of democracy, religion and social attitudes toward homosexuality. In two-thirds of the American statehouses where legislation has passed, or is in process, the bill legalizing same-sex marriage was sponsored by a gay legislator. In two of those states, the very first person to be married under the new law was the state legislator who sponsored the legislation — Beth Bye in Connecticut and Karen Peterson in Delaware. Openly gay legislators send a clear message to their straight colleagues: If you are going to vote against this measure you are going to have to vote against me, as a person standing in front of you.

The events of the last decade validate the plea that Harvey Milk made in his election speeches in California. In 1978, he defined his run for office in San Francisco with the mantra that for gay people to be treated equally, they must have a seat at the table. Visible gay leaders, out of their closets, needed to run for and be elected to public office to shatter the fear generated by the myths swirling around their invisibility.

Individual representatives around the globe who picked up Milk’s credo have made manifest the link between descriptive representation and substantive policy change. Louisa Wall brought marriage equality to New Zealand. Sunil Babu Pant persuaded the Supreme Court of Nepal to recognize the “third gender” community as a specially protected minority group. The British Lord Waheed Alli, the first gay, Asian and Muslim parliamentarian anywhere in the world, by his own force of personality helped engineer the most comprehensive overhaul of gay rights in the history of any established democracy, overturning the unequal age of consent (in 2000), Section 28 (in 2003), bringing in Civil Unions (in 2004) and ultimately same-sex marriage (in 2013).

As an MP, Zakhele Mbhele will be challenged from many quarters, but he represents much more than symbolism. The evidence of the last 40 years suggests that rapid progress only comes after a tipping point of social change has been reached. But the simple presence of an openly gay office-holder is a game changer.