In the year 2154, Captain Archer of the starship Enterprise briefly rocked Klingon forehead ridges thanks to a genetic virus. Combined with this detail and the new leaked photo of Klingons on Star Trek: Discovery, there may be emerging proof of a missing link between the Klingons with bumps and the Klingons without bumps.
On February 11, a behind-the-scenes photo leaked on Twitter of several Klingons from Star Trek: Discovery. These new Klingons don’t look exactly like original series Klingons, but they don’t look quite like “normal” Klingons either. Though the have bumps on the back of their head, their foreheads seem flatter than most of the famous ridged Klingons of the majority of the canon. In the original Star Trek, Klingons didn’t have their signature bumpy foreheads first glimpsed in Star Trek: The Motion Picture and subsequently throughout the rest of Star Trek canon. Instead, they just had long mustaches and were generally more “human.”
But, the human-looking Klingons thing was retconned in an episode of Enterprise called “Divergence” which explained that the smooth-headed Klingons were the result of a genetic experiment gone wrong. Klingons tried to make better warriors by using leftover genetic material from the “Augments,” the same group of genetically souped-up humans of which Khan was an infamous member. Crossing the Khan-esque DNA with 21st century Klingons resulted in smooth-foreheaded Klingons. KHAAAAN!!!!
So, from the 22nd century to the 23rd century, a bunch of smooth-headed Klingons were running around the alpha quadrant. But, by the time of Worf’s 24th century, the real-deal big-bumpy forehead Klingons were back in full force. Because Discovery takes place ten years before the original series, there should be smooth-headed Klingons hanging around unless, at this time, there were also genetic missing links between the smooth-headed mutated Klingons and the normal Klingons from the rest of the canon. After all, not all forehead ridges are the same.
In Star Trek VI: The Undiscovered Country, General Chang had tiny forehead ridges, similar to the ones Captain Archer temporarily grew in “Divergence.” This look was similar to the rebooted alternate universe Klingons in Star Trek Into Darkness, proving that really big forehead ridges might not have made a full comeback right away in the 23rd century. And the Klingons glimpsed in the behind-the-scenes photo look way more similar to Chang and the Into Darkness guy than they do Worf on The Next Generation.
A working theory for this difference is that the Discovery Klingons are a generation of Klingons in-between Worf’s 24th era and the humanoid mutant Klingons from the 22nd century. That means that the new different-looking Klingons on Discovery might not contradict canon at all, but instead, they continue to explain the bumpy genetic road of the entire Klingon race.