for the longest time we floated in the seas

we became multicellular, specialized

then we got bones, to better eat others in the seas

then we became frogs, to survive, and still laid
eggs in the sea, wet.

then we made hardshelled eggs, so we could live without water.

then, we internallized the eggs, without shells, so we could protect them better.

along the way we got lungs, scales, feathers, fur, tits.

but the repro is the big design change.



so little appreciated.