Humans are said to be getting uglier — and it’s got nothing to do with aging, according to one expert.

Shafee Hassan, a founder of facial aesthetics consultancy firm QOVES, explained the phenomenon in response to a question about why old high-school yearbooks “contained [so] many attractive people… was it something in the water?”

Hassan explains in the caption on a clip posted to TikTok, “The average person’s face is becoming increasingly disadvantaged by modern diets, sleeping patterns, pollutants and orofacial habits creating a greater inequality in ‘the attractives’ vs ‘the unattractives’.”

He begins the video — which has garnered 3.2 million views and 333,100 likes — by asking if the viewer has ever wondered why teenagers in the 1950s look “so much older” than teenagers today, meaning that teenagers previously appeared more adult-like with more defining features.

“There are multiple theories about why this is the case, but the one that makes the most intuitive sense, at least to me, is presented in Contemporary Orthodontics by [US orthodontist William] Proffit and colleagues using what’s known as the functional matrix hypothesis,” he said.

He explained, in simple terms, that the functional matrix hypothesis means that “development of the face is dependent on the forces you put on it, for the upper and lower jaw,” which is what tends to define an “attractive or handsome” face.

Hassan continues by saying that the tongue or “other forces” can push the jaw downwards or outwards and a new bone will fill the space it’s created by movement.

Showing photo examples of a little girl with an underdeveloped jaw, the facial analyst claimed that a long-term sinus infection impacted the growth of the lower jaw since she was breathing through her mouth and didn’t keep it closed enough to “develop properly.”

“With 70% of the Western world having some kind of malocclusion [misaligned upper and lower teeth] or recession, much like this, it’s a very good explanation for why faces are becoming less and less attractive as time goes on,” Hassan concluded.

His hypothesis suggests that how we are using our mouths — and the foods we put in them — can impact the development of our jaws.

Some viewers on TikTok weren’t convinced, claiming that “fashion, photo quality, and factors like smoking cigarettes” is what made the generations of yore appear older than their age, according to one keyboard critic.

Another suggested “that we associate hairstyles with age,” and the perceived aging effect would disappear if we tried “to add modern hair on those faces.”

At least one fellow expert agreed with Hassan’s theory, writing, “I’m in dentistry and this is absolutely accurate.”