CM Punk and Daniel Bryan's rise to the top of the WWE is proof that the only constant is change.
Transport Punk back to the '60s, with his tattoos, piercings, Muay Thai influence and 218-pound frame, and WWE fans of that time would stare confused at a man who doesn't belong. He and Bryan would have been odd fits for the black-and-white era of the sport or for Hulkamania.
They would be primates trying to live in a world ruled by dinosaurs.
The WWE Superstar, however, has changed over the years, absorbing elements from outside sources and shifting what fans expect their heroes to look like. Before we arrived to a present where a man Bryan's size is arguably the most popular man on the roster, WWE looked vastly different.
The Sammartino Age
Power ruled WWE's early days.
Bruno Sammartino, the top Superstar for much of the '60s and '70s, was a former powerlifter who trained alongside Arnold Schwarzenegger. He resembled a circus strongman, barrel-chested with muscles bulging around his neck.
This was what many a WWE Superstar looked like back then.
Ernie Ladd, Don Muraco and Billy Graham were all large, powerful men. It was an age of mostly simple ring gear, burly men and few gimmicks.
A WWE ring was a showcase of toughness and strength with men clamping headlocks on each other or wrapping their foes in bearhugs. Aside from exceptions like Jimmy Snuka, wrestlers didn't leave the ground often.
Superstars from this era represented little variance from the sport's origins. The entertainment part of the equation was increasing, but WWE was still a showcase of virility and power that evoked images of wrestling's pre-TV days and beyond.
Heading into the '80s and into Hulkamania, the physiques stayed mostly the same, but the glitz amplified.
The Hogan Age
WWE Superstars' adaptations in this period included brighter colors, tassels, face paint and taking on more over-the-top characters.
Sammartino and Muraco shared a lot of traits with Hulk Hogan and Ultimate Warrior, even if those two pairs looked drastically different. Being built like a boulder was still common. Being over 250 pounds was still common.
Compare it a T-Rex maintaining the same shape as it evolves but developing stripes or colorful, speckled skin.
There were certainly exceptions, Randy Savage being one example, but big was still king.
Andre the Giant and Hogan were both WWE champs. The first few WrestleMania main events featured the enormous King Kong Bundy, as well as Andre and plenty of Hogan.
This wasn't a high point for in-ring talent at the top of the company. Few would argue that Hogan or Warrior were elite wrestlers. Instead, they were performers and entertainers, as well as more interesting characters than their predecessors.
Even as popular as he was, it's hard to imagine a Sammartino action figure outselling a Hogan one.
WWE's Superstars during this era helped sell T-shirts, were represented in cartoon form and turned the WWE ring into a comic book come to life. Some of those elements dwindled some as WWE headed into the mid-to-late '90s, but the biggest change was a move toward smaller stars.
The New Generation Age
The shift was partially out of necessity. The Ultimate Warrior, Hogan, Andre, Big John Studd and Bundy were all gone. WWE's most talented remaining men didn't fit the muscle-bound mold of the part.
Bret Hart stood at 6'1'' and was about 234 pounds. Shawn Michaels was a few pounds lighter.
Together, these two Superstars held the WWE Championship for a good chunk of the '90s. That marked a significant adjustment to what a top Superstar looked like.
Both men were faster, more technically skilled and more versatile than many of the folks from the Hulkamania period. Behemoths still roamed the ring, men like Diesel, Sycho Sid and Yokozuna, but there seemed to be a new focus on agility and ability over size.
Partly inspired by the likes of Snuka and other early high-flyers and partly as a result of an infusion of Lucha Libre-style wrestling, Superstars began to add more dazzling moves to their repertoire.
This was only the beginning, though, as WWE Superstars would strive to entertain by any means possible in the next several years.
Redefinition and Revolution
During both the Attitude and Ruthless Aggression Eras, Superstars continually looked to push into the future with innovation and fearlessness.
To make a name for themselves and to separate themselves from the past, men began to take unimaginable risks.
New molds phased out the ones that had created the wrestling stars of yesteryear.
Superstars were increasingly varied. Top talent came in overweight and undersized forms.
Men like Foley, Chris Jericho and Eddie Guerrero held the WWE title. Giants and powerhouses never went away, as evidenced by Big Show, Triple H and Brock Lesnar's reigns, but diversity at WWE's top was increasing.
Hardy would have likely been too skinny and too strange looking to make it some of the eras before his. Would Edge have been considered too small? Would Jericho have been relegated to tag team duty or jobber status?
Along with their look, a Superstar's role underwent change as well.
In Sammartino's day, one had to be a wrestler and little else. Superstars in the late '90s and early 2000s increasingly had to become multifaceted. They were as much comedians as they were dramatists and were equal parts brawlers, wrestlers and stuntmen.
Two of that period's top stars, Steve Austin and The Rock, earned their lofty position largely on being able to excel at all of those roles.
Both men could deliver an intense fight as seen in parts of their WrestleMania bouts, but also made us laugh during segments like this one.
Superstars now fought in violent, dangerous matches that didn't even exist several years prior, such as Hell in a Cell, Ladder matches and the Elimination Chamber. The job's difficulty increased and it required more charisma, more athleticism and versatility than ever before.
The Present and The Future
WWE appears to be headed in the direction of increased agility, speed and skill.
John Cena, Ryback and Mark Henry still represent the powerhouse role, but overall the WWE Superstar is getting smaller and sleeker.
Bryan, Cena's opponent at SummerSlam, is 5'10". He and Punk are just two of the "undersized" stars succeeding today. Seth Rollins and Dean Ambrose both hold WWE gold. Dolph Ziggler, coming off a world title reign, is about 215 pounds.
Beyond the decreased emphasis on size, WWE has moved toward an in-ring style that is a conglomerate of MMA, Lucha Libre, brawling, mat wrestling and WWE tradition.
MMA moves like Punk's Anaconda Vice meld with planchas and hurricanranas from Mexico as Superstars' toolboxes are forced to get bigger in order to entertain fans. Should a newcomer copy Sammartino's move set today, they'd likely be booed out of the building.
As each generation has stepped up the risk and the entertainment value of the action in the ring, fans have come to expect more.
Taking a look at WWE's developmental system, NXT, one sees a future teeming with faster, more mesmerizing athletes.
Men like Sami Zayn, Adrian Neville and Samuray Del Sol represent a continued shift away from brute strength to a product flush with dazzling moments and impressive speed. WWE is wise to not stay mired in the past. The dinosaurs gave way to the mammals and the same appears to be true for WWE's big men.
Large warriors will never go away, but the kingdom will be ruled be the small, the quick and the gifted as WWE's landscape continues to evolve.