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This Cat Makes No Sense

2019-11-04 · explainer · Hank · 4:00 · watch on YouTube

Topic: Science & nature · mode: Explainer · tags: recurring series, calendar ritual, self promotion

Hank introduces John to the manul, or Pallas's cat, and its puzzling round pupils: vertical pupils suit low-light ambush predators like it, and he walks through three theories of why (muscle range, blur-based distance judgment, multifocal lenses), concluding its pupils are an adorable mystery; he then reopens the Bizarre Beasts pin club until Pizzamas ends.

What is said

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

00:00:00 — The manul: range, solitary habits, long fur, stealth hunting, one-day fertility windows

  • ★★ Hank says the manul, or Pallas's cat, is a wild cat roughly the size of his cat Cameo, but the two only look similar. — 00:00:00
  • ★★★ Hank says Pallas's cats range across Tibet, China, Pakistan, India, Mongolia and Iran, living solitarily on small rodents and birds, with the longest hair of any cat, stealth hunting and fertility windows as short as one day a year. — 00:00:00 · China

00:00:29 — Pallas's cat's round pupils versus the vertical pupils of low-light ambush predators

  • ★★ Hank says vertically slitted pupils evolved separately in cats, foxes, alligators, snakes, even some birds and sharks. — 00:00:29
  • ★★ Hank says big cats lack vertical pupils, most small cats have them, and the moderate-sized European lynx has intermediate pupils. — 00:00:58
  • ★★★ Hank says animals with vertical pupils are hunters in low light and ambush predators; Pallas's cat meets all those conditions yet has round pupils. — 00:00:58
  • ★★ Hank says nobody knows how Pallas's cats ended up with their round pupils. (unsure) — 00:00:58

00:01:27 — Three theories of how vertical pupils help ambush predators: musculature, blur and stereopsis, multifocal lenses

  • ★★ First theory: vertical pupils contract with a curtain of muscle strands rather than a sphincter, letting them contract and expand more, though the loris shows this is no hard rule. — 00:01:27
  • ★★ Second theory concerns distance judgment, vital to ambush predators: animals judge distance by sight through parallax, binocular stereopsis and blur. — 00:01:27
  • ★★ Hank says low to the ground the depth of field is shallower, and vertical pupils seem to keep horizontal blur for distance judging without losing the vertical contrast stereopsis needs. (hedged) — 00:02:26
  • ★★ Third theory: with a wide aperture colours focus differently, so cats evolved lenses with focal gradients; a circular pupil contracting blocks the blue-optimized zone, a vertical pupil keeps all of it. — 00:02:26
  • ★★★ Hank says none of these theories is certain, but a vertical pupil would clearly suit Pallas's cat's lifestyle, so its round pupils are an adorable mystery. — 00:02:55

00:03:24 — Bizarre Beast of the month and the Bizarre Beasts pin club reopening until the end of Pizzamas

  • ★★★ Hank names Pallas's cat this month's (November 2019) Bizarre Beast and says the Bizarre Beasts pin club reopens until the end of Pizzamas, with a new beast's pin and info card every month. — 00:03:24 · Pizzamas
  • ★★ Hank invites viewers who want the Pallas's cat pin to join the pin club right now. — 00:03:24

In the description and comments

  • ★★ The description says Pallas's cat split from its ancestors 5 to 6 million years ago, when our ancestors were still interbreeding with chimpanzees' ancestors. — video description
  • ★★ The description suggests the useless pupils make the cats cute to humans and so may help save them by keeping captive breeding programs going. (hedged) — video description

Threads in this video

Where the stories that moved here went next

Mentioned

Central: Pallas's cat · pupil

Also: Projects: Bizarre Beasts Pin Club · Pizzamas

Concepts: ambush predator · cat · chromatic aberration · convergent evolution · depth perception · Eurasian lynx · shark · slow loris

Places: China · India · Iran · Mongolia · Pakistan · Tibet

animal: Cameo

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