> north-south pooping orientation would naturally dominate. No need for a sixth "compass" sense.
What if it's both? Compass sense helps align them north/south for better vantage even when the clouds obscure the sun at the start of defecation/urination.
I skimmed the study and did not see anything regarding having controlled for day/night/cloud cover.
That's a hypothesis that can be checked. Go over the data and splice it by time of day, or rather position of the sun given the location/time/day of year. Then you should see a much higher correlation when the suns out than when pooping at night.
What if it's both? Compass sense helps align them north/south for better vantage even when the clouds obscure the sun at the start of defecation/urination.
I skimmed the study and did not see anything regarding having controlled for day/night/cloud cover.