If you want a solid barometer of how America is changing, when it comes to race relations, take a look at professional sports over these last few weeks.

I’ve been an avid sports fan for my entire life, growing up in awe of the most brilliantly audacious and loud-mouthed sports figure we’ve ever had. His name was Cassius Clay, and later Mohammad Ali. Anyone who missed Ali at his prime, as a dancing boxer who could “float like a butterfly and sting like a bee” while reading poetry at press conferences to enrage his opponents, missed one of the great chapters of American racial history and its relationship to sports.

I admired Ali long before I really noticed that he was black. Only later did I appreciate that before Ali burst onto the scene black sports stars were supposed to be quiet and demure. Ali was loud and proud, and he could back it up. “I am the greatest,” he yelled from the ring’s ropes, “and I am beautiful.”

Ali was a transformative figure in race relations in America, not because he asked for respect, but because he demanded it.

Sports, like America, has had plenty of dark moments in race relations. Baseball’s Negro Leagues perfectly reflected America’s segregated society in the first half of the 20th century. But competitive athletics are the closest thing to a meritocracy we have in this country. If you’re good and can help a team win, you advance. It’s that simple. In sports, as perhaps nowhere else but in combat, people want to win more than they want to hate.

When an idea like racial equality flourishes among educated elites and academics, it’s a sign of progress, but when it penetrates the sports world, and in particular its many younger men, it has become the new norm. In a very short time, we’ve gone from epithets thrown at Jackie Robinson and Muhammad Ali to a generation of fans, like our young son, who are entirely color blind.

It’s been an enormously encouraging, hopeful and relentless advance, without which the successes of Martin Luther King and Barack Obama may not have been possible.

Over the last two weeks, we saw just how far that transition in racial attitudes has come. First, the billionaire owner of the Los Angeles Clippers basketball team was banned for life from the NBA for racist comments recorded in the privacy of his home. Ironically, 75 percent of the Clippers’ players and its coach, Doc Rivers, are black.

A little closer to home, the Boston Bruins lost a heated playoff game to their arch-rivals, the Montreal Canadians, when P.K. Suppan, one of hockey’s few black players, scored in double overtime. After the game, the Twitter-sphere lit up with ugly racial attacks.

Just a few years ago, those comments would have gone unanswered, encouraging others to join in and pile on. Not this time. Not now. The Bruins, the NHL, talk show hosts across the country and fans everywhere spoke out with forceful clarity.

Bruins president Cam Neely called the comments “racist, classless views expressed by an ignorant group of individuals.” NHL Commissioner Gary Bettman added, “We are about diversity and inclusiveness. We condemn bias and hatred.” Bruins captain Patrice Bergeron spoke for other players when he said, “There’s really no room for this in 2014 at all.” Bruins coach Claude Julien went further: “People who think that way are not what we call our fans. It’s a shame that this is still going around in this day and age.”

Each of those comments came from a white man working in a blue-collar sport. What they said would not have been expressed 10 years ago. Together, they were proclaiming the end of an era in which racism was quietly accepted in professional sports, and for that matter anywhere else. Millions of fans, and especially younger fans, were learning from them the rules of the game, not just in sports, but also in life.

When the history of our time is written, from the vantage point of the year 2100, one of its most prominent chapters will be about the civil rights movement, and the successes of Martin Luther King, the NAACP and Barack Obama. The influence of blacks in the arts, music and theater also will be celebrated. But the role that sports have played in overcoming racism in America will be an essential part of that uplifting story.

This week, I’m particularly proud to count myself among the sports fans of America.

Alan Caron, a Waterville native, is president of Envision Maine, a nonprofit organization working to promote Maine’s next economy, and co-author of an upcoming book titled “Maine’s Next Economy.” Email at alancaroninmaine@gmail.com.