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Why birds do not fall while sleeping

(news.cnrs.fr)
230 points mdp2021 | 5 comments | 15 Oct 24 08:56 UTC | HN request time: 0s | source
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ndheebebe ◴[17 Oct 24 02:17 UTC] No.41865817[source]▶
> The only permanent bipeds of the animal kingdom alongside humans

Kangaroos?

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dhosek ◴[17 Oct 24 02:25 UTC] No.41865856[source]▶
Kangaroos engage in quadrupedal (actually pentapedal—using their tail as well) locomotion at slow speeds.
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defrost ◴[17 Oct 24 02:30 UTC] No.41865877[source]▶
So do humans, babies and the elderly especially.

What has 4 legs in the morning, 2 in the afternoon, and 3 in the evening?

The key here is how relaxed is the interpretation of "permanent".

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seszett ◴[17 Oct 24 05:07 UTC] No.41866588{3}[source]▶
> So do humans, babies and the elderly especially.

Only the healthy adult form is taken into account generally, you wouldn't say that dragonflies are mainly swimming animals for example, even if they do spend most of their life underwater as larvae.

The point here is that kangaroos that are capable of bipedal motion will always choose quadrupedal motion at low speeds. While humans who can walk will always choose to walk when possible.

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sorrythanks ◴[17 Oct 24 06:56 UTC] No.41867095{4}[source]▶
Adults crawl all the time
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1. silisili ◴[17 Oct 24 07:02 UTC] No.41867125{5}[source]▶
Adults never choose to crawl, unless in tight spaces or drunk off their rocker.
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2. 867-5309 ◴[17 Oct 24 07:16 UTC] No.41867187[source]▶
you've never been to a teetotal claustrophile bdsm party
3. ◴[17 Oct 24 09:06 UTC] No.41867744[source]▶
4. avar ◴[17 Oct 24 10:06 UTC] No.41868061[source]▶
Yes we do, e.g. there's a sweet spot when scaling an incline (especially if there's easy handholds, e.g. a grassy incline) where using all fours is much easier and natural than making the same trips on two legs, even though you'd be perfectly capable of doing that too (i.e. I'm not talking about proper wall climbing).
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5. macintux ◴[17 Oct 24 12:49 UTC] No.41869181[source]▶
You’re right, but if I can extrapolate from myself to most adults, that’s approximately never.

I think I’ve done that once in the last 10 years, and I spend a fair bit of time in the woods.