this is blowing my mind.

https://youtube.com/watch?v=On2V_L9jwS4

in this video Hank Green says so. they claim that basically, any wet tissue where lots of blood flows through can absorb oxygen from the air, and that lungs did not evolve 300 million years ago when fish stepped out of the water and onto the land, but as early as 420 million years ago, supposedly because it allows fish to survive in water that is depleted in oxygen, as stale warm water often is.

for this purpose, fish would open their mouth and swallow air from above-the-water, sothat the air enters their gut, where oxygen is absorbed into the bloodstream. since the gut has a large internal surface area, this supposedly works; and lungs are just a more efficient version that developed out of this scheme.

wait let me check with wikipedia. https://en.wikipedia.org/wiki/Lung#Evolutionary_origins doesn't seem to confirm or deny it, it just says that lungs developed "from a sack near the oesophagus".

the article Lungenfische (german for lungfish) seems to mention it:

Die Lunge der Lungenfische ist ein Organ am Darm, das homolog zur Schwimmblase ist.

Translation:

The lungs of lungfish are an organ on the intestine that is homologous to the swim bladder.

but the english article about lung fish seems to mention instead:

As in tetrapods and bichirs, the lungs extend from the ventral surface of the esophagus and gut.

so we have "attached to the intestine" vs "attached to the esophagus and gut". i'm not sure.

lungs evolved out of the digestive system

this is blowing my mind

Seems more like your mind is being digested

This is genuinely one of the coolest things I’ve learned about evolution. Thanks for this! There’s always that step that I’ve seen brought up about fish moving to land, but I can’t recall anyone mentioning in context about the oxygen depletion in water.

It’s almost covered in Bill Wurtz’s History of the World: https://youtu.be/xuCn8ux2gbs?t=190

The inner-net say so...so it must be so! Just take it! ...dat booty gonna hurt a bit. :-)

Bird lungs are crazy too

Wait until you hear about a proposed new emergency method of keeping patients with respiratory failure oxygenated: enteral ventilation.

Some turtles do this naturally.

Human Trials Bring Us Closer to Breathing Through Our Butts.

Human Centipede Brings Us Closer to Breathing Through Someone’s Butt

You probably don't have many people in your life that respond to you in a timely manner.

Humans are only walking digestive tracts. From an evolutionary perspective, all other organs originated from a primitive gut and have only one purpose: to serve it.

Both the esophagus and the gut are part of the digestive system. To have the lungs fold out from this system before the stomach makes the most sense.

Basically they put 1,5 l fluid into their asses just to check if its feasible, without oxygen yet. Meanwhile, porn industry shoves anything up their bottoms, from fluids to bottles to pickle jars. Real question would be if oxygen would be absorbed in a meaningfull amount. What an oversight.

Well, that pickle jar didn't get absorbed very well...

When the pickle jar leaves the anus, we mark it a success.

What is a nose and lung if not eating the air?

birds are basically balloons

check how insects breathe

they don't even have lungs I think

You could go deeper and say that all organs including the gut's purpose is to serve the gonads.

Yeah they have tiny holes called spiracles in their abdomens, which are each connected to multiple branches of trachea that go directly into their tissue

If inhaling is eating, then exhaling is pooping

And if we exhale CO2, then soda technically has poop bubbles in it

Thanks for that thought

So we're eating poop in the air then because we're breathing CO2 in as well.

everything is poo

the poo of stars