I’d say the silliness seen here goes hand-in-hand with curiosity and intelligence, which makes them clever and effective hunters. This type of derpiness also earns them a rent free spot in monkey houses. So, dumb as it may seem, this is actually a very fit behavior.

Your premise is mistaken. The cat is rubbing its scent glands/scratching its cheek (and shoulder) on the stairs’ edges, to satisfy an itch and mark its property simultaneously. Sliding down the stairs is merely a benign side effect.

What is the evolutionary advantage?

Preservation of energy. Anti-parasite behavior.

The temperature in your house is too high … because your cat has taken to its liquid form.

Well, cats are basically liquids, so flowing down the stairs is actually the expected behavior.

It’s called “de-escatlation”. Just like de-escalation, but with an awkward hiccup.

slinky cat!

i think stairs can just be awkward for cats to navigate too. they are designed for human feet…

Sometimes when I’m really tired in the morning I get out of bed like this, it’s the path of leadt resistance.

Felis Slinkere!

Tbh, the most compelling idea of why animals play that ive heard is just as a way to keep the body limber and ready. Its like free form yoga and calisthenics combined if youre playing hard

… Drunken Tiger Paw?

Looks like a sidewinder snake.