Why Are We Warm-Blooded?

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A human with the metabolism of a hummingbird would need to eat about 80,000 calories a day to survive. That’s because staying warm by making your own heat takes a ton of energy. And that brings up a paradox, because creating your own body heat is incredibly expensive. The largest animals on Earth have to spend most of their day just eating enough to keep their heat engines running. So why aren’t we cold-blooded… like crocodiles? Here’s the science

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[premnaren]

Warm blooded animals- I'm chilly! *shivers*
Cold blooded animals- I'm chilly *goes into a temporary coma*

[Jjjj-uewq]

"Being this hot is hard work" I can relate

[OverlordMaggie]

I'm glad it was addressed in the subtitles - for those who don't use them, being so warm can also impede infections, hence how we fever when we're sick or go hot locally when we have an infected wound!
Fungi in particular pise a huge problem to reptiles and amphibians, so a theory is that being so warm helped birds and mammals suffer fewer fungal infections.

[davidalfonsoportillomiramo]

I just wanted to point out that there's actually around 50 species of lizards that can run on two legs (frilled lizard and bearded dragons to name some popular ones, ) this seems to happen because once the lizard reaches top speed, the laws of physics force them into an upright position so they can run faster. Maybe it was worth mentioning though that most lizards can't run and breathe at the same time. Love this channel, keep up the good work!

[jaysabol]

Just real quick, I wanna say thank you to this channel and others PBS supports for allowing me to go down rabbit holes like these. The way you encourage education is phenomenal, and i'm glad that one day my kids will have a this channel to watch with me

[commentor]

There is probably a dad in the body that controls the internal temperature and he has to stop people from touching the thermostat.

[ylhajee]

I've heard (I think on Scishow) that body temperature is correlated to how susceptible to fungal infections animals are. So one more advantage of warm-bloodedness may be that you get fewer fungal infections. Do you know how accurate this is?

[Najakeeper]

Crocs are great parents. They wait by their nests without feeding for months and some dig and carry their babies to water in their mouths. Babies also call for their parents when in trouble. Better parents than some people I know for sure.

[klazienanalenveehouderkweker]

I like how the globe being sassy has become a running gag

[erikziak]

I guess Shrewdinger is both cold blooded and warm blooded when you do not look at it.

[minutemansam]

I'm surprised he didn't bring up pregnancy possibly being the stepping stone for warm bloodedness. Many reptiles and fish become partly endothermic while they are pregnant, so warm bloodedness could potentially be a trait that is beneficial for organisms that do internal fertilization, instead of external fertilization.

[perialis]

warm blooded animals: man its winter :/

cold blooded animals: lmao im loggin off till its next year see you later man

[vir]

Fyi crocodile might win the parenting award coz ..a documentary from Attenborough described how gentle they can be while handling babies just hatched ..also they run full day care for other Crocs ...and take care of them

[andrewvirtue]

I feel like this somehow explains why that when I was a kid, I would go outside and just lay in the parking lot in front of my apartment. I enjoyed the heat that radiated from the road. Or go sit in my moms car as it cooked in the summer sun. Because I was really under fed, and was always hungry!! This makes sooo much sense!

[miraculousmarrtian]

The Egg in the frying pan was a classic. Best way to educate about drugs. Just say they all melt your brain.

[otavio.a..r]

Great video. I just wanna add that this could also be explained by how heat helps some enzymes to work in a more efficient way. Furthermore, heat also accelerates the movement of molecules improving the efficiency of some molecular reactions. As you mention, life outside the water might require larger amounts of energy, so faster molecular reactions were really useful for these animals so long ago.

[domc]

So if the shrewdinger is the ancestor of all placental mammals, does that mean that technically all cats are... shrewdinger's cat? :D

[corwin]

8:30 The dino was actually saying, “oh crap, this is going to WRECK the economy”

[johngrace]

“Crocodiles aren’t winning any parenting award” - when they’re the single best parent among the non-avian reptiles.

[hanifanzak]

6:57
Collared lizard can run on 2 legs too
Sailfin dragon and frilled dragon are also able sprint on 2 legs