Mammal and avian yawn comparison

[Pajarita]

This study is a bit long and it has a lot of formulas and stuff BUT it is super interesting! They figured out that the duration of yawns is directly related to the size of the brain and the number of neurons in it (yawns are needed to 'cool off' the brain) and that birds tend to have shorter yawns compared to mammals with the same size brain- most likely because the birds have an 'extra feature' that mammals don't have, the rete mirabile ophtalmicum, which works like the countercurrent exchange that the birds have in their feet so they don't freeze (veins and arteries so close together that they keep the blood temperature constant) only, in the head, it works to keep the blood cool instead of warm. Now, isn't that super cool?! I tell you, birds are EXTRAORDINARY creatures with bodies so much more efficient than mammals'!!

https://www.nature.com/articles/s42003-021-02019-y