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The Weirdest Thing About Dogs (and Cats (and Horses))

2026-05-15 · explainer · Hank · 5:40 · watch on YouTube

Topic: Science & nature · mode: Explainer

Hank tells John that a 2019 PNAS study found dogs, unlike wolves, have a muscle that lifts the inner eyebrow; he argues that dogs, cats and horses were not simply bred to be cute or to manipulate us but evolved ways to communicate their real emotional states to humans.

What is said

The parts of the video and what is said in each (★ — how much it matters to the video).

00:00:00 — A begging dog's sad look and its eyebrow-like features

  • ★ Hank says the dog in the clip clearly wants something, maybe cheese, and that he would give it to the dog if he knew what it was. (hedged) — 00:00:00

00:00:30 — The 2019 PNAS study: the inner-eyebrow muscle in dogs but not wolves, uncanny wolves, filmed eyebrow raises

  • ★★ Hank says dogs, like humans, have little eyebrow-like features that seem to work mainly for communication, and that wolves do not have them. (hedged) — 00:00:30
  • ★★ Hank says researchers published a paper on this in PNAS in 2019, joking about how the journal's abbreviation sounds. — 00:00:30
  • ★★★ Hank says the team dissected the heads of dead dogs and wolves and found that dogs have the levator anguli oculi medialis, which only lifts the inner eyebrow, while wolves at most had a thread of tendon. — 00:00:59
  • ★★ Hank thinks the missing muscle is why wolves look uncanny: friend-shaped, but their eyes say they are not friends. — 00:01:28
  • ★★★ Hank says the researchers filmed 27 dogs and nine wolves with a stranger nearby; the dogs raised their inner eyebrows consistently and more intensely, and all the most intense raises were dogs'. — 00:01:28

00:02:16 — Not bred on purpose: Hank's view that eyebrows are communication tools, not just cuteness; horses and cats

  • ★★★ Hank says the eyebrow muscle is not a trait people deliberately bred into dogs: no one 25,000 years ago picked pups for inner-brow movement; something else happened, which we cannot know exactly. — 00:02:16
  • ★★★ Going beyond what scientists would say, Hank thinks people very likely cared more for dogs that had these muscles, though not simply because they were cuter. (hedged) — 00:02:44
  • ★★ Hank explains neoteny: domestic animals come to look more like the baby versions of their species, and so cuter. — 00:02:44
  • ★★★ Hank says neoteny is only part of it: dogs' eyebrows also show curiosity and where the dog is looking, so like ours they are communication tools, not just cuteness makers. — 00:02:44
  • ★★ Hank says that, among many theories, it seems obvious to him that human eyebrows are mainly for sharing information, and that their hair adds contrast that lets the movement say more. — 00:03:13
  • ★★ Hank says some dogs also evolved this contrast around the eyebrows, which he finds extremely cool. — 00:03:43
  • ★★ Hank says there is evidence that horses' facial muscles evolved for horse-to-human communication. — 00:03:43
  • ★★ Hank says cats changed their faces less but seem to have developed a whole different set of vocalizations for communicating with humans. (hedged) — 00:03:43
  • ★★ Hank calls the internet fact that house cats are stuck in kittenhood (only wild kittens meow) the same kind of simplification as saying dogs evolved puppy-dog eyes to manipulate us. — 00:03:43

00:04:12 — Against the kitten and puppy-eyes simplifications: companion animals evolved ways to share their minds with us

  • ★★★ Hank's simpler explanation: a cat's calls and a dog's eyebrow raises track the animals' emotional states, and the animals benefited as they became better at helping us understand them. — 00:04:12
  • ★★★ Hank says companion animals had the same inner states before; they evolved new tools (calls, body language, panting, tail-wagging), each species in its own way, to get their minds into ours, and he loves that. — 00:04:41
  • ★ Hank says cats in the wild meow less to each other but have many ways of communicating with each other that do not work well on humans. — 00:04:41
  • ★★ Hank announces the Project for Awesome 2026 grant recipients, congratulates them and points to a link in the description. — 00:05:10 · Project for Awesome

00:05:24 — Sign-off and the P4A 2026 grant recipients announcement

Threads in this video

  • milestone · P4A 2026 edition — Hank announces the Project for Awesome 2026 grant recipients, congratulates them and points to a link in the description. (00:05:10)

Where the stories that moved here went next

Mentioned

Central: 2019 PNAS study of dog and wolf facial muscles · animal communication · dog · levator anguli oculi medialis

Also: cat · domestication · eyebrow · horse · neoteny · Project for Awesome · uncanny valley · wolf (concept)

Only in the description or credits: Proceedings of the National Academy of Sciences

Also centred on dog: Cats are Better than Dogs, I Proved It. (PG-13)

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