Cam Newton and the "dab" celebration isn’t all that different from other quarterbacks’ celebrations, Kevin Blackistone argues. (Grant Halverson/Getty Images)

In his documentary “Unforgivable Blackness: The Rise and Fall of Jack Johnson,” Ken Burns pointed out that 1890s heavyweight boxing champion Jim Corbett earned the sobriquet “Gentleman Jim” because of his defensive, scientific style of fighting that was the antithesis to the brawling that made the sport.

Johnson, who fought in a similar style later in the same era, wasn’t afforded such a compliment.

“With black boxers, every trait that was a positive trait, they [the media and public it influenced] tried to turn it into a negative trait,” Purdue University historian Randy Roberts, who focuses on sports and popular culture, observed in the film. “If a black boxer was tough and could withstand punishment, well, he could withstand punishment because his skull was thicker, because he was insensitive to pain, that it was really a sign of some larger inferiority.

“If he was a smart boxer, a wily boxer,” Roberts continued, “then he was slightly deceptive. . . . There was something untrustworthy about his activity in the ring.”

Unforgiveable Blackness,” replaying this week on PBS as homage to Black History Month, reminded that what Carolina Panthers superstar Cam Newton expressed last week, causing debate this week — about his blackness being a factor in negative perceptions about him — is not a novel observation. Instead, it is part of a long history of media and public criticisms of black athletes, most ironically regarding characteristics for which white athletes are often admired.

It is also a reminder that what we see in sports more often reflects society than influences it. Indeed, an Associated Press poll four years after this country elected as president its first progeny of a black parent found that anti-black feelings among U.S. citizens was up to 51 percent among all, and up to 59 percent among non-Hispanic whites. So what Newton wondered aloud was far closer to reality than his own perception.

Black athletes’ self-confidence is interpreted as cockiness, their aggression construed as lack of control, and how they wear disappointment after losing is read as immaturity, to name a few critiques. And their talent often is acknowledged mostly as a byproduct of birth rather than of much hard work.

In the hundred years or so between Johnson and Newton, there have been other black athletes similarly criticized, like the star NFL halfback Joe Lillard. Lillard was a standout in the league in the early 1930s and just as cantankerous as many white players then, but was castigated for being so. The league became so fed up with Lillard that some suggested he was the reason it decided in 1933 to bar its locker-room doors to men of African descent, an effort of racial segregation the NFL maintained until after World War II.

There was Silvio García, an Afro-Cuban whom Branch Rickey originally tapped in 1945 as his guinea pig to trot out onto Major League Baseball’s all-white diamonds. But Rickey, the president of the Brooklyn Dodgers, rejected García because he saw García’s tenacity, admired in others, as a detriment. So the story goes, Rickey met with García in Havana and asked him, “What would you do if a white American slapped your face?” García responded: “I kill him.”

And then there is Muhammad Ali, Jim Brown, Kareem Abdul-Jabbar, even Barry Bonds, et al.

I interrupt this essay out of obligation to so many of Newton’s detractors to acknowledge that, yes, he was arrested while at the University of Florida on felony charges for stealing a fellow student’s laptop. The state reduced the charges and deferred prosecution because the victim declined to join the prosecution. Newton was required to attend counseling, write an apology letter and do community service. He eventually transferred to a junior college to reboot his college career, which culminated at Auburn with a national championship and Heisman trophy.

Those of us in the media don’t, however, feel so compelled to highlight the legal troubles of white athletes, like, for example, another former star Southeastern Conference quarterback now in the NFL, Zach Mettenberger. He was dismissed from Georgia after pleading guilty to two misdemeanor counts of sexual battery, grabbing the breasts and touching the buttocks of a woman at a bar. Mettenberger was sentenced to two concurrent 12-month periods of probation, ordered to pay $2,000 in fines and perform community service. Like Newton, he transferred to restart his career, and wound up at LSU, where he starred before being drafted by the Tennessee Titans, for whom he now plays.

But Mettenberger doesn’t dab, a dance created and popularized in the hip-hop culture around Newton’s predominantly black home city of Atlanta that Newton performs after a score. The dance garnered Newton criticism that he was egotistical, and somehow a poor role model for kids, rather than enthusiastic about accomplishment. Conversely, white star athletes like Green Bay Packers quarterback Aaron Rodgers, who I like for his stellar play and social consciousness (he stood up for unions in Wisconsin when Gov. Scott Walker attempted to crush them, and rallied against African child labor in the cellphone industry) is just as demonstrative with his touchdown celebration. Rodgers pretends to don a championship wrestling belt, which concludes with a thrust of his pelvis as suggestively as Elvis. It gained Rodgers not rebuke, however, but an endorsement contract with State Farm.

And when Newton announced late this season that he and his longtime girlfriend were having their first child, the Charlotte Observer in the town he now calls home printed a letter to the editor that took Newton to task for having a child out of wedlock. When it was announced that New England Patriots superstar quarterback Tom Brady fathered a child with his ex-girlfriend Bridget Moynahan after moving on to Gisele Bündchen, sportswriter-turned-academic Ronald Bishop at Drexel found that much of the media explained the event as “. . . metrosexual trappings that come with [Brady’s] global celebrity.”

Newton is, as he declared, a black quarterback who unsettles some onlookers. He doesn’t cloak himself in the self-emasculation of black athletes so celebrated in this country from the first half of the last century, like Joe Louis, Jackie Robinson or Olympic star Jesse Owens, who is further immortalized this month in the new movie “Race.”

Newton is not necessarily without comparison, as he suggested, but a 21st-century manifestation of Ali’s fearlessness. He is not only exercising his freedom to be who he wants to be, but as his Beats By Dre commercial with rapper 2 Chainz’s “Watch Out” in the background suggests, he feels no fear in letting anyone know, either.

Kevin B. Blackistone, ESPN panelist and visiting professor at the Philip Merrill College of Journalism at the University of Maryland, writes sports commentary for The Post.