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submitted 1 month ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] Fedizen@lemmy.world 3 points 4 weeks ago* (last edited 4 weeks ago)

Idk if "descendants of omnivores" counts because then you could exclude a number of critters like pigs for being "descendants of herbivores" and then 'why do pigs have more stereoscopic vision than a t-rex '

The obvious caveat is that pandas at the minimum don't have selective pressure for side eyes or they have something pressuring stereoscopic vision even more similar to how aquatic animals have less selective pressure for forward facing eyes.

I would imagine the way pandas eat bamboo stalks is more visual than most herbivores and that alone could help them retain steroscopic vision.

[-] vaultdweller013@sh.itjust.works 1 points 4 weeks ago

I was trying to imply that pandas did it recently enough for such pressures to not have kicked in yet. Probably should've specified that a bit better.

[-] Fedizen@lemmy.world 2 points 4 weeks ago* (last edited 4 weeks ago)

That's the speculation on gut length in pandas based on statistical methods but panda teeth are already well adapted to eat bamboo so selection has been working on them for some time or at least there is no opposing selection at work in panda teeth preventing them from changing. Strangly the large canines are used to cut the bamboo which might be what created their niche in the first place, but their teeth are otherwise very different from other bear teeth.

Its been a while since I dove into this but from what I remember the speculation with gut length has to do with metabolic tradeoff. If pandas don't get that tradeoff with the food they eat then they'll probably keep their current gut length. Or they might make a different tradeoff (slower peristalsis, more gut surface area)

[-] squaresinger@lemmy.world 2 points 3 weeks ago

Google tells me that pandas started eating bamboo 6-8 million years ago and stopped eating meat 3 million years ago.

That's not exactly recent.

For reference, the first Homo appeared 2.8 million years ago and the first Homo Sapiens 300 000 years ago.

The last common ancestor of humans and chimpanzees lived 5-10 million years ago.

So if evolution can evolve humans in that time frame, you'd expect that it could also adapt an omnivour to a herbivour.

[-] vaultdweller013@sh.itjust.works 1 points 3 weeks ago

Huh I legit thought they were a more recent species, like last glacial maximum. Is this one of those things like with the three toe sloth and two toe sloth where they are on opposite sides of their evolutionary tree but look generally similar? Are pandas kinda like sun bears where they are more or less doing their own thing while black, brown, and polar bears stay grouped weirdly close to each other in behavior.