their bodies adapted to have a bigger spleen.
I wonder if it's in their genes are just how their body grows from them holding their breathe a lot and training it like a muscle.
your spleen basically stores oxygen rich blood cells and releases them when needed.
there's another tribe whos eyes adjust to see better under water (moken people I think)
their pupil can go smaller than a normal humans I think it was 1.5mm vs 2.4mm
