As MMA has evolved, UFC champions have become younger and younger.
The days when a 40-something Randy Couture could return from a 13-month hiatus to capture the heavyweight title are likely gone for good. Many hungry up-and-comers now fill every division and are knocking the majority of their elders down a peg well before they close in on 40 years old.
Obviously, there will be exceptions.
Anderson Silva hung onto his spot atop the middleweight division for years. While many would have begun to fade at his age, "The Spider" was only recently dethroned by Chris Weidman.
Here are the 10 oldest champions in UFC history.
Age: 34 years, three months (12,532 days)
Evan Tanner had an opportunity to capture a UFC championship at 30 years old, but he was slammed into unconsciousness by Tito Ortiz at UFC 30.
It took four more years, seven wins and a move to the middleweight division for Tanner to get another shot at UFC gold. At UFC 51, he met David Terrell for the 185-pound title, which had remained vacant for years following Murilo Bustamante's move to Pride FC.
More than 30 fights into his MMA career, Tanner stopped Terrell with ground-and-pound in the first round to capture the 185-pound championship.
His reign didn't last long, though. Four months later, Rich Franklin came along and claimed the belt by stopping Tanner for a second time in approximately two years.
At 34 years old, Tanner's MMA career headed in the wrong direction quickly following his loss to Franklin. He went on to lose three of his next four bouts before tragically passing away in the deserts of California.
Age: 34 years, four months (12,543 days)
Sean Sherk received his first shot at a UFC title in April 2003, when he lost to MMA legend Matt Hughes in the welterweight division.
Better suited for a lightweight division that was struggling to stay afloat under the UFC banner, Sherk competed outside the Octagon for a couple of years following that loss. Not long after returning to UFC competition, he met Kenny Florian in a fight for the vacant 155-pound championship.
Sherk bested Florian on the scorecards to become the UFC's first lightweight titleholder in more than five years. He then sat on the belt for nine months before defending it against Hermes Franca.
Months after his win over Franca, Sherk was stripped of his championship as a result of a failed drug test. In today's age, he would have been punished more swiftly and wouldn't have surpassed Evan Tanner by one month for the No. 9 position.
Age: 34 years, four months (12,544 days)
When Randy Couture vacated the UFC heavyweight title in 1998 due to a contract dispute, Bas Rutten was brought in to vie for the open championship.
By beating Tsuyoshi Kohsaka in his Octagon debut, Rutten earned a spot in a title fight with Kevin Randleman. "El Guapo" won that matchup in a split decision to claim the belt, but he too vacated the championship in preparation for a drop down to the now-light heavyweight division.
Before he could even begin his run at 205 pounds, heretired from MMA due to injuries. Broken down when he was on top, Rutten could have found himself much higher on this list had he been able to remain healthy.
Age: 35 years, one month (12,840 days)
Already 23 fights into his MMA career, Pat Miletich became the first UFC welterweight champion, although he was then named lightweight titleholder, by beating Mikey Burnett via split decision in October 1998.
Miletich held onto his belt for more than two years, becoming one of the older champions in UFC history before being unseated by one of the youngest ever, Carlos Newton. Miletich may have been on his way to a decision win, but he was caught in a bulldog choke during the third round at UFC 31 and had to tap.
At 35 years old, he only had four fights left in him after that loss. He never received another shot at a UFC championship.
Age: 35 years, five months (12,964 days)
Shane Carwin didn't get his MMA career started until he was 30 years old.
It then took the Colorado native nearly five years to rise to the top of the heavyweight division and earn a shot at the interim UFC heavyweight title against Frank Mir. For the 12th time in 12 career MMA bouts, Carwin picked up a first-round stoppage against Mir at UFC 111.
A few months later, he welcomed fellow champion Brock Lesnar back to the Octagon.
After hurting Lesnar in the opening frame, Carwin seemed ready to continue his run of quick finishes. However, Lesnar survived and submitted a gassed Carwin in the second stanza.
With a comfortable engineering job to fall back on, he fought only one more time before retiring, losing to Junior dos Santos.
Age: 36 Years (13,157 days)
Maurice Smith began his combat sports career as a kickboxer and didn't get started in MMA until he was already into his 30s.
Still, he didn't take long to become one of the top fighters in the heavyweight division. Less than four years after debuting under the Pancrase banner, he dethroned original UFC heavyweight champion Mark Coleman in a decision.
While Smith only held onto the belt for five months, he did defend his championship against Tank Abbott before losing to Randy Couture in a majority decision. If that close decision had gone the other way, Smith probably would have owned the No. 4 position on this list over the next fighter.
Age: 36 years, two months (13,216 days)
Despite coming off his first MMA loss in a bout with Chuck Liddell, Murilo Bustamante was awarded a shot at UFC middleweight champion Dave Menne at UFC 35.
Bustamante stopped Menne with strikes in the second round to dethrone the first 185-pound titleholder. The Brazilian held onto the belt for nine months and defended it against Matt Lindland before having it stripped due to his move to Pride FC, where he lost his first three fights.
By leaving the UFC, he hurt the promotion's middleweight division. It went without a champion for years until the aforementioned Evan Tanner finally replaced Bustamante.
Age: 37 years, five months (13,674 days)
Chuck Liddell began his MMA career inside the Octagon in May 1998, but it took him almost seven years to get a shot at an undisputed light heavyweight championship.
When he did, "The Iceman" made the most of his opportunity.
In a rematch with Randy Couture, Liddell scored a first-round knockout to capture the 205-pound title. He went on to knock out out his next four challengers before running into a rematch with Quinton Jackson, who defeated Liddell a few years earlier under the Pride FC banner.
Again, "Rampage" was able to stop Liddell, who would win only one more fight before being chased from MMA competition following three more knockout losses in succession.
Age: 38 years, two months (13,963 days)
For a while, it looked like Anderson Silva was going to be knocking out top middleweight contenders well past his 40th birthday. Then came along Chris Weidman.
Silva won the middleweight title at 31 years old with a brutal series of knees against Rich Franklin. For nearly a decade, "The Spider" maintained his championship and was rarely threatened by those who challenged him.
At UFC 162, Silva was finally dethroned by Weidman, who was unfazed by the champion's mid-competition showboating. In December, Silva had an opportunity to avenge that loss, but he instead suffered a gruesome leg injury and may never return to being the same fighter he once was.
Age: 45 years, four months (16,583 days)
Randy Couture is the oldest champion in UFC history, and he will likely forever hold that distinction.
At the age that Anderson Silva was dethroned by Chris Weidman, Couture had just begun a second out of three heavyweight title reigns. He also still had two stints as a light heavyweight champion ahead of him.
It wasn't until he ran into an athletic specimen like Brock Lesnar that his days as a champion were behind him. Even then, as he crept toward 50 years old, Couture won three of his final four MMA bouts.
Many are ready to call the great Silva done as a serious title threat now, and he's still several years younger than Couture was when he stunned Tim Sylvia to win his final UFC championship.
These days, it would be shocking to see a fighter at Couture's age reach the pinnacle of MMA. It was surprising enough then.